How to image and create disks for retro computers

well hello everyone and welcome back to Adrian's digital basement on today's video I'm going to cover a topic that I seem to get questions about a lot and it's how I go around and make discs for various systems that I work on in this video I'm going to be giving my PC that I usually use to do this task which is this computer right here an upgrade so I can read and write more disk types than I can in this machine so without further Ado let's get right to it [Music] thank you foreign if you're into Retro computers and you probably aren't you're watching this channel one of the most difficult thing about using these old computers is the fact that the disks that are used to store programs and load games and stuff like that can be very difficult to get your hands on now you might be lucky and have a required an old computer or maybe you already had yours from when you were a youth that still has all the floppy disks and they work well what if you want to download a piece of software off the internet and then use it on your old computer and that means you have to put it onto a disk or you could potentially be buying an old computer whether it be a Dos PC or a lot of other computers that use floppy disk and it didn't even come with any disks and of course if you had that computer when you were young all those discs are gone so now you have no way to use the computer now I wish I could tell you that there was one machine you could set up or something you could buy that could read and write every single disk format super easily unfortunately that's just not the case it's a little bit more complicated than that now there exists commercial disk archiving systems like this here the cryoflux and there's an OP open source alternative called the grease weasel plus I think there's something called the zoom floppy and are specifically designed to hook up to a modern computer and allow you to Archive basically read in the data off a disk onto a modern computer a Mac windows or Linux PC typically the data from these types of devices is actually saved to something called a stream file which actually records the actual magnetic flux information that's on the disk well a digital version of it into a large file on your computer that's basically an exact replica of the disk these things are great if you're trying to recover disks that are partially bad or they have copy protection things like that and it is possible to take that stream file and then reverse it basically write that back onto a physical disk and that absolutely does work with these you start to run into problems with these disk archival systems when you're trying to write a disk image you download off the internet back onto a disk because those image files are never in the Stream format that these things natively work in they're usually some other format designed for you with emulators I could probably make a whole series of videos on using these archival systems for reading and writing disks and it's really beyond the scope of this video what I'm going to be talking about in this video is using a PC as in a Dos PC to read and write disks of many different types of computer systems first though we have to cover a few Basics about the way disks are actually written by computers because I'm not good with fancy Graphics programs like David Murray on a big guy I'm going to be drawing some things on a Post-It note for all to see if you want to use an IBM PC compatible machine to read and write disk images like I predominantly do on this channel you have to be aware of the disk encoding or the floppy disk encoding method used to make the disks a disk is really just like a tape like an audio cassette and information on an audio cassette or any magnetic media device is stored in the analog domain so if you're going to store digital information on something that's analog you need an encoding method to convert that Digital Signal into an analog one and then when you read that signal back off the disk you have to reverse that process to convert that analog signal on the media back into a digital signal if you ever used a modem back in the day to dial it to the internet this was no different because of course a modem is connected to an analog phone line that's designed for carrying a voice sound signal and it has to take a digital signal or Digital Data and encode that into a way that can be sent over the analog line and then converted back to digital on the other end and actually here's a little bit of interesting tidbit about modems the technology of what a modem did got better and better over the years which is why early modems were 110 or 300 bits per second and used a very simple encoding scheme to send the data over the analog line well phone lines didn't really get better quality over the years and they did a little bit but generally the amount of bandwidth available on an analog phone line was the same throughout history and what enabled the modem to hit 56 000 bits per second was much more advanced in coding techniques that were developed down the road anyhow let's get back to the topic of disks there are predominantly three types of encoding methods that are used on floppy disk especially five and a quarter inch discs like this there's FM or frequency modulation MFM or modified frequency modulation and GCR I don't remember what GCR stands for off the top of my head but it is a different format than these other two there is also an other type I put down other typically systems that use this other encoding method are very old systems from like the mid 70s or early 70s and they are doing that because there was no off-the-shelf disc controller ICS they could buy that would use one of the standard formats therefore they kind of went their own way and those types of formats can really only be read and written using the actual disk controller itself on that machine or using something like a disc archival system which read and write the actual flux information right off the magnetic media luckily those types of disks are pretty rare and generally everything else falls into one of these three formats now when it comes to IBM PCS and reading and writing disks the disk controller that's on these types of controllers now this is one that techselect made here but there are many that are all compatible with each other on the IBM PC and these can read and write in the FM and the MFM format only systems that use the GCR format which means you cannot read and write those disks are things like the Apple II all the Commodore disk formats well at least the five and a quarter inch ones and the Macintosh 800k discs which are written on three and a half inch disks there are other systems as well that may use GCR and those discs will not be read and writeable at all in this system with any type of regular disk controller card that is compatible with like the original IBM PC this controller that was found in the original IBM 5150 the FM encoding scheme is also known as single density so if you see disks that say single density single-sided that's going to be using the FM encoding scheme MFM which came later increases the amount of storage capacity on a disk and it's called double density incidentally the high density disk format which you may know for things like three and a half inch disks like this HD one here and also five and a quarter inch discs uses MFM encoding the fact that it's high density has nothing to do with the encoding method it has more to do with the data rate and in some cases the number of tracks on the disk I'll talk about that more in a second now I can probably hear you asking why did Apple and commodore go with the GCR format instead of using one of the standard ones well I think the answer is twofold GCR is more efficient at storing data on the disk than FM so you just get more on your disk even though it's the same physical disk you're able to store more data on it in addition disc controller chips like the one that's found on this card right here were probably pretty expensive and if you look at the Apple II disk controller card it's a pretty ingenious design where all of the complexity of reading and writing the disk is actually handled by the CPU of the computer and not a dedicated controller chip like on cards like this so as a way to save money was probably decided that it just wasn't even worth using a controller chip and he just did it himself and he did it in a very elegant way that offered more storage capacity as well now luckily for enthusiasts like us most systems use FM or MFM encoding because they are just using an off-the-shelf controller IC which was a lot easier than designing your own system entirely from scratch and that's a great thing because that means a disc controller card just like this one which is actually manufactured in 2022 can read and write all the FM and MFM encoded disks on a regular dos PC using a piece of software like IMD or image disk by Dave dunfield I will talk about IMD a little bit more coming up but for now there's some more differences on disk formats that we need to talk about before we get to actually testing some of this stuff out on a real computer foreign ly it's not just the encoding method of the data on the disk that you have to worry about if you're going to try to make disks remember I mentioned that this is just a plastic disc with Magnetic material on it there is no actual physical layout of the way the data needs to be encoded on this disk it's purely up to the way the disk drive is designed and the way the computer writes the data onto it there are various physical characteristics of the original disk drive in the computer you're trying to make a disc for that you have to match to be able to read and write disks from that particular computer on the five and a quarter inch disk drives there are generally three types of physical ways to write the track data onto the disk very common on older machines are 48 track per inch disk drives and those typically write 35 or 40 tracks on a disk the difference there with those extra five tracks is simply the head moves further on the 40 track drives than it did on the 35 track drives as far as I'm aware sugar Associates invented the five and a quarter inch disk drive format the physical characteristics of it and their original mechanism the sa-400 was 48 tracks per inch most early systems use 48 track per inch disk drives the Apple II does even with its GCR encoding as does the Commodore the original IBM PC and many many many other types of disk drives that have that large full height five and a quarter inch disk drive are using 48 track per inch mechanisms that means if the encoding method is FM or MFM like we talked about already then a 48 track per inch Drive hooked up to an IBM PC can read and write those types of disks properly now in order to allow more data to be stored on disks using the same encoding method the drive manufacturers started creating 96 track Branch drives which basically doubled the number of tracks from 40 to 80 on the same physical media so even though this is a regular double density disk here and you think this is only good good for 40 tracks of data it can actually be used in well what I think is called a quad density Drive which writes 80 tracks onto this disk and that effectively doubles the storage capacity on the same physical media systems that use these drives typically got about 720k of storage on one disk a double-sided disk using MFM encoding when of course if you remember that typical MFM encoding on a double density 40 track disc results in about 360 K of storage unfortunately there is actually one more type of physical way to write tracks onto a disk and it is a hundred tracks per inch versus 96. it still results in the same amount of storage space but the difference between 100 tracks per inch and 96 is large enough that if you try to read a disc that was written on the other type of mechanism some of the tracks are going to read but then it's going to start to get more offset as the head moves across the disc and it's just not going to work properly systems that used 100 tracks per inch are definitely a little less common and 96 and 48 are by far the most common but I've still run across some discs that are written on 100 tracks per inch and you'll figure that out if you try to read one of the 96 track Sprint Drive when some of the tracks just start to completely not read at all properly incidentally the 48 track per inch drives write down a thicker track onto the magnetic media than the 96 track Branch drives so if you try to read a 48 track per inch disc in a 96 track per inch disk drive like a 5 and a quarter inch high density drive on a PC it probably is going to read properly because what happens is the operating system will double step the heads so even though it's an 80 track drive it's going to read 40 tracks by double stepping but if you try to write information back onto the disk what gets written down onto the disk is much thinner than the original wide track that was written by the original drive so while it might read back okay on the high density or the 80 track drive if you put that disc back in the original 48 track per inch Drive which has a wider head or track width it's probably going to read both the original signal it was written with the wider track and the new thinner track they'll be crosstalk so really ideally if you're going to be working with diss a lot like I do you really want to stick to the 48 track per inch drive if the original discs or the original machine has that type of drive or 96 for the same or of course 100 you have to use 100 otherwise it's just not going to be compatible I haven't really touched on three and a half inch discs but basically they're always 80 tracks the only difference in high density and double density is the actual data rate that's written onto these These are generally Always written in MFM although maybe FM ones exist out there but it's MFM encoding and then there's two different data rates 250 kilobits per second and 500 kilobits per second and actually this data rate difference also exists in the five and a quarter inch world as well and generally everything that is considered double density or single density so FM or MFM single density or double density is always going to be 250 kilobits per second now it is actually possible to use 500 kilobits per second on a five and a quarter inch disk and that is the high density disk format and the reason why that exists is because IBM took the original eight inch disk drive and they shrunk it down to five and a quarter inch size all of the physical characteristics of the 8-inch Drive the speed of the disc spinning the data rate it writes set everything was just shrunken down and that is what the high density disk format is it's a little bit of a hack on the original five and a quarter inch disc standard and honestly it kind of confuses thing and I wish IBM hadn't done it but they obviously wanted to be able to increase the storage of those five and a quarter inch discs and just taking all of the physical characteristics of the eight inch disc and shrinking it down was how they accomplished that otherwise if it's MFM or FM encoding on a five and a quarter inch disc it is written at 250 kilohertz per second now that brings me to the question of RPM or revolutions per minute the original five and a quarter inch to standard ran at 300 RPM that's what it runs at three and a half inch discs also run at 300 RPM there are some weird outliers like the Macintosh 800k format has like variable speed and there are some 8-inch disk drives like the disk drives that HP used on their HP 150 those run at 600 RPM but generally if it's FM or MFM encoding on a five and a quarter inch or a three and average disk it's running at 300 RPM we run into issues with that high density disk drive that IBM designed again for the original 5170 those drives typically are configured to run at 360 RPM because that is what 8-inch disk drives run at and IBM like I said shrunk down the format that poses a problem if you try to read a disc on one of those drives that was written on a 300 RPM 250 kilobits per second drive like a regular double density Drive reading and writing that disk is going to be at the wrong data rate because the disk is physically spinning faster so there's actually a third data rate that these types of controllers support the ones that were designed later in use on the IBM PC and later and it's 300 kilobits per second basically 300 kilohertz per second plus a disk drive spinning at 360 RPM reading and writing a disk that was written on an older drive that runs at 250 means it's actually going to line up and work unfortunately that complicates things if you download a disk image of a double density disk that was made on a high density disk drive on a PC essentially the disk image is going to want to write back to the physical disk at 300 kilowatts per second but if you're writing a double density disk back to a double density disk on a proper 300 RPM 48 track per inch drive it needs to be written at 250 kilobits per second or it's not going to work hopefully with all of that talking I just did that gives you a little bit of information about all the different physical characteristics and disk encoding methods used on disks to help you kind of have a base knowledge that will allow you to use some of the tools I'm going to be talking about coming up in the rest of this video foreign if you're looking to get a machine set up that will allow you to make and read and write disks for all sorts of different systems let's talk about the things you're going to need to make that happen the first thing you're going to need of course are physical disk drives what this is is a double-sided 48 track per inch disk drive it runs at 300 RPM it's made by Toshiba it would be basically what you would think of as a regular 360k pc disk drive it uses the normal Edge connector which is typical for the five and a quarter inch drives it's a typical sugar pinout and this is pretty much just a bog standard drive next up I have a teac 96 track per inch disk drive here typically known as a standard high density disk drive from a PCAT since this is a 96 track per inch drive it writes with a thinner track width which is appropriate if you're going to be reading and writing any discs that come from a machine that also use a 96 track Branch drive and lastly I have this disk drive right here what's special about this particular disc draw while it looks like a normal full height double-sided Drive is this is actually a Tandon tm100-4m and there's a very special thing about these particular 4M drives if we flip down the lid here and you take a look at the inside it says 100 track per inch yes this is actually a 100 track per inch double-sided disk drive pretty rare thing in the grand scheme of things because as I mentioned 100 TPI drives are just quite rare the drive has a standard sugar Edge connector just like the other drive so it can be used in any PC just like the other two drives I just showed now when we look at these three drives there's the 48 track Branch drive this is the 100 track Branch drive and this is the newer 96 track per inch high density disk drive these two drives are designed only to use 250 kilobits per second as the data rate while this high density Drive of course supports 500 kilowatts per second and 250 and the 500 kilos per second as I mentioned is that compatibility with the original 8 inch straps which all used 500 kilobits per second and then the fourth type of disk drive of course is this which is just a normal three and a half inch drive this is a regular 1.44 Meg high density mitsumi drive not much to say about this all these drives are 80 tracks so they're all pretty much compatible with each other it's 300 RPM and it supports 250 kilobits per second and 500 kilobits per second data rate so yeah you could pretty much read and write all three and a half inch discs with this oh I do want to add that there are other types of three inch disk drives this type of mechanism on this was I think invented by Sony and that's pretty much what became the standard there were other types early on like the amstrads use those of course are physically different than this although I'm quite sure that they just use MFM or FM encoding as well so the actual encoding method is the same and I think even the signaling is the same the sugar type signaling the connector may be different but the actual digital signals are the same so I would imagine you could probably plug one of these drives into your am strap ad make a disk image on the PC onto a regular three and a half inch drive and then it would it would work on your amstrad of course it wouldn't physically fit in the computer because the size of the drive is a little bit different I'm not really going to do much more talking about these types of drives and let's get back to the five and a quarter inch drives which are the more complicated and harder to figure out format so if you're looking to build up a Dos computer to be reading and writing disks of these other types of computers you got to think about what type of disks you're going to be trying to make most likely you're probably going to want yourself a 48 track per inch disk drive like this a double-sided one that's going to give you compatibility with all the systems that use single and double-sided 48 track per inch drives of course if they're using FM and MFM encoding which is most of them of course it goes without saying that three and a half inch drives are pretty cheap so I pretty much recommend you get one of these and throw it in there as well if only because you can buy a USB floppy drive and plug it into a modern computer and then copy files to and from your dos computer really easily if you don't want to go through all the extra effort or setting up a network stack stuff like that and this is the PC I showed early on and I've been using this for quite a number of years and basically it's got a 360k drive or 48 track Branch drive and a three and a half inch drive and it suited me really well I've made so many discs on this thing for so many types of systems it's been really useful and very versatile now you might be asking what about high density discs and I do occasionally need to read and write those but I have an IBM pc5170 sitting right there and it has a high density disk drive in it so I actually just use that computer the truth is these types of high density disks were only used in IBM PC compatibles and pretty quickly three and a half inch high density discs replace these types of discs so there just don't seem to be a whole lot of these floating around don't get me wrong though I'm not saying that having 96 track per inch Drive is useless I'm just saying that it seems like many more computers use 48 tracks per inch so if you have to pick one I would pick 48 but if you have room to have both in there and I would actually do that because there are plenty of other systems besides IBM PCS that do use 96 track per inch discs and if you don't have that drive obviously you're not going to be able to read and write that format now this is the 96 track Branch drive that I'm going to be using in my new archival pc and the thing that's really cool about this drive and it is a tiac fd-55gfr-633-u really long and convoluted model numbers on these the thing about these tag drives and luckily they're very common and they're also very reliable is that some of them and this is one of them have actual jumpers on the bottom to configure the drive to run at two speeds when five and a quarter inch disk drives went from the full High drives like this 100 track per inch Tandon here down to this half height they went from a belt drive for the spindle motor down to a brushless induction motor like this one here basically there's a speed controller on the disk drive I think it's on this little circuit board right here that allows it to run at a very precise speed so there's probably a little hall effect sensor on the underside of this and there's coils and stuff and this thing can lock on exactly to the right speed it needs to run at this is of course different than these types of drives here which have a drive belt and they also have a little potentiometer on the back here for adjusting the speed because this thing uses a much simpler speed control circuit than these newer drives so because of this more sophisticated speed controller some of these high density disk drives like this one have a jumper setting that you can set that actually allow it to run at dual speeds there is a signal that comes across the floppy drive cable pin 2 typically the signal which comes from the floppy Drive controller tells the disk drive when appropriately configured hey I'm trying to read a high density disk at 500 kilobits per second which it's just like the 8 inch disk format so the disk drive will in turn run the disk or spin the disc at 360 RPM when the disk controller on the computer is trying to then read double density or 250 kilobits per second that signal goes to the disk drive and when that jumper is set it will run the disc at exactly 300 RPM it is having a drive that's dual speed really absolutely necessary I don't really think it is but because the IBM PC disk controllers support that 300 kilobits per second data rate which allows it to read and write those 256 kilobit per second disks at the increased 360 RPM what a 96 track Branch drive like this running at 300 RPM allows you to do is use this drive on an older computer that only supports a data rate of 250 kilowatts per second like a TRS-80 model 3 for instance I could plug this drive into there and actually use all 720k on that system with a regular double density disk because of the 80 tracks that this drive supports unfortunately there is no easy way to know if the drive that you have supports that speed change without looking up the manual if you can find it because a lot of these disk drives don't have manuals and seeing if there's a jumper you can configure to allow that dual speed nature of the drive I happen to have a Mitsubishi drive here this is also a 1.2 megabyte 96 track per inch drive and it also has jumpers and a manual online that I have looked up to run this thing in dual speed and I tested this drive and it absolutely works perfectly it runs at a perfect 300 RPM or 360 RPM depending on the signal going into pin 2 on the drive so with all of that said I want to set up a PC that can basically read and write everything that has the MFM or FM encoding so I'm going to be using this 96 track Branch drive here dual speed set up for dual speed I'm going to be using this 100 track per inch drive here which always runs at 300 RPM and I'm going to be using this 48 track per inch drive as well runs at 300 RPM all of these in the PC simultaneously along with three and a half inch drive like this so I can read and write pretty much all of the FM and MFM encoded discs that are out there in a five and a quarter inch format and also in the three and a half inch format ultimately it goes without saying I'm not going to be able to read and write eight inch discs and I'm also not going to be able to rewrite the three inch disc like the amstrad uses because well I don't have those physical drives hooked up to this computer okay I have done so much talking at this point let's build up the computer that holds all these drives so it's kind of obvious that my idea of putting all of those disk drives into this case isn't going to work there's just not physically any space so I have a solution for that and this is the solution this is an ATX case versus an at case like the other one and as you can see by the front cover here it has plenty of five and a quarter inch Drive Bays four to be exact which is actually perfect for the fact that I want to put two half height drives in there and I want to put a full Height Drive in there it also has two exposed three and a half inch Bays you're probably looking at this and wondering what are these toggle switches in this rotary knob for well the rotary knob was for a different project and I'm going to be using the toggle switches on this machine actually I'll get to that in a little bit it has nothing to do with the floppy drives it's just more to adjust the clock speed of the motherboard I currently have this wire soldered onto it so it can go to the motherboard but yeah the three and a half inch floppy Drive will stick through the front and then of course all the rest of the drives will be on the top here as I mentioned this is an ATX case and clearly the motherboard that's in that other case is an at motherboard I'm not sure if everyone realizes this but you can actually mount an at motherboard into an ATX case and generally the standoffs are all in exactly the right position obviously ATX motherboards extend further up to the top here and the ATM motherboard stops around here or at least a baby at motherboard and the keyboard connector will just stick through the opening on the back of the ATX case here where the normal ports are for this build I'm not going to be using the ATM motherboard from the other machine I'm going to be using this one here the Asus p5a 200 megahertz MMX same speed processor that's on the other machine but this motherboard has the benefit of an AGP slot which is roughly if I recall correctly twice the bandwidth of these old PCI slots so that's a nice Improvement for your video card I'm glad it has a couple Isa slots though because I want to be using Sound Blaster 16 card and I'm going to need to be using a floppy controller like this one here from techselect not out yet sorry about that but Kevin will have this out soon I think it's going to be white it's going to look a little different but the reason why I want to use this with this motherboard as opposed to the built-in floppy Drive controller on the motherboard is because of course this has two connectors for up to four floppy drives the original floppy drive standard that was invented by shugart for their first drive supported up to four floppy drives drives like zero one two and three originally with the standard the way you selected which Drive was which was by setting jumpers here to select which Drive was which and all of the drives were just connected in parallel to each other when IBM came up with the original pc5150 they took the floppy drive standard that was the sugar standard and they changed it up a little by adding this twist into the cable The Twist uses up a couple of the extra wires that were available to select four drives originally and made it where one of these cables can only handle up to two drives but the benefit is you set both drives to drive select one and depending on where you connected on the cable if it's before or after the twist is what selects which Drive you're using back to the floppy Drive controllers the fact that there's only two drives supported was just a wiring thing and the actual controller ICS all the way back to the original one used on the IBM pc5150 Drive controller supported four drives you know in the hardware at least it's just from a wiring perspective there was no way to utilize that and the way Kevin wired up this card all I need to do is use two of these cables these regular pc compatible cables select all the drives to drive select one have drives one and two on this connector and drives two and three on this connector and then a program like IMD can actually address all four of them alrighty with that said it's time to take apart the other computer put this motherboard in here and build this thing up and I'm going to do a jump cut there we go the build is complete it wasn't too hard to get everything in this computer because it's a relatively roomy let me show you a close-up of how everything is connected up starting from the bottom slot we have a sound blaster 16 CT 1740 and this has the I think it's the ASP chip on there the advanced signal processor attached to the soundblaster 16 is Yamaha XG sound card plugged into the expansion connector there so for anything that uses midi I can choose to either use the FM synthesis on the sound blaster or the XG midi capabilities of this Yamaha card next up is the text select floppy Drive controller and all four drives are connected to it using two standard PC ribbon cables with the twist in them next up is a compact flash to IDE adapter and this sticks the compact flash through the back of the computer and that's the ribbon cable that goes up to the motherboard then we have a 10 100 PCI ethernet card this is an Intel variety and then lastly we have an AGP TNT vanta video card I gotta say these Nvidia TNT cards make really quite good dosed video cards they seem to support all the various modes for dos and they support Visa 3.0 up to well 1024 by 768 High color 32-bit color and they of course are very Speedy being AGP next up is the Intel Pentium 200 megahertz MMX and I have overclocked this which I'll talk about in a second and then we have this power supply here provided by Big Steve here in Portland this is a normal ATX power supply but what's important about this one is it has the minus five and the minus 12 volt rails on it which is is perfect I don't know if the Sound Blaster actually needs both of those but the thing is this power supply provides them that's just normal for all of my builds I always take any extra parts from the case like these are the front Bay covers and also some Drive rails and I put them in a bag and stick them inside the case that way they don't get lost looking at the front of the machine of course this computer fits all of the drives the first drive is the a drive here this is the 360k or 48 track per inch Drive the B Drive is this one the three and a half inch disk drive C is the 1.2 Meg driver the 96 track wrench drive at the top here and D is the 100 track per inch drive right there so my viewers are probably going to be bugged by the fact that these are not in order like a through D unfortunately the reason for that is that this case was not designed to ever hold full height disk drives it actually has these sliding rails which stay integrated and I had to remove the two from this part right here to take this full High Drive and then I tried to put the a drive on the top but unfortunately it doesn't work because for whatever reason this drive rail up here it grips the top set of the screws on the disk drive and this older 360k or 48 track wrench drive only has screws on the bottom let's talk really quickly about how to connect up all four drives to this disk drive controller card we have to keep in mind that since this is only one controller chip all of the signaling that goes across these wires are all in parallel except for the drive select signals that go to the drives because of that fact that they're all In Parallel Drive termination actually does matter you only want to have two Terminators one on the disk drive controller and one on one of the drives so I remove the termination from the other drives and this is actually working perfectly now I'm sure lots people are asking what's the deal with these toggle switches for the two toggle switches here what I've done is I've run these to the front side bus jumpers on the motherboard so when these are both down in this position the CPU is actually run at 100 megahertz which is an overclock with them both in the up position Edition it's run at 66 megahertz which is the standard speed and one of these down is 83 megahertz and the other one down the other one up is 75 megahertz so I have a selection of four different front side buses to pick from by moving these switches around now the clock generator on this motherboard requires it to be powered off and then you flip the switches because if you just switch these while it's running like it is right now it doesn't actually do anything so these switches really are just convenient way to change the overclocking of this CPU without having to open the case up and like move the jumpers around all right I have the machine hooked up to the capture device let's take a look at how I have this thing configured so if you try to replicate this yourself you can do so I move the compact flash card from the other computer so this has a Windows 98 install on it but I mainly go into dos now I have a boot menu configured and this comes from Phil's computer labs he's the one who I originally got the boot menu from I just modified it for my use case as I had mentioned before IMD or image disk by Dave dunfield is the best program to be using for MS-DOS when you're Imaging or working with disks from other systems there's a few things about IMD that you might not have realized if you've ever used this program before if we go to drive in the settings all we can pick from is a or b what about the other two disk drives that exist on this machine well taking a look at imd.text which is the included documentation that comes with it there are a whole bunch of command line options as you can see here and look at the very first one slash four assume four drives per floppy Drive controller and remember this text light card that I'm using has one controller for four drives so that's the option we need it does also support a second floppy Drive controller at a different i o address but the thing you have to worry about is that flopping Drive controllers on the PC also use dma channels and unless you can change the dma channel the two controllers may stop on top of each other as you can see here there are a whole bunch of other settings that you can set from the command line most of these can be configured in the settings in IMD but for whatever reason number of drives that the program supports can only be set from the command line there is another important option here that can also only be set from the command line and it's this one down the bottom LR or lock data rate I do have to use that on this machine because this dual speed disk drive so I'll talk a little bit more about that in a second so here in the boot menu I have two options set one of them is just four drives which basically puts that slash four after IMD and the other one is force 250 kilobit which is that lock data rate I just mentioned and the only time I wouldn't want to force 250 kilobit is if I'm actually reading and writing high density disk drives and either the 96 track per inch drive or the three and a half inch Drive since those around 500 kilobits I have to enable that setting but in all other circumstances if I'm working with discs they're 250 kilobytes the force option is actually appropriate I'll explain why in a second first let's start with this disc right here I have this formatted on the 100 track Branch drive so if we slide this into the full Height Drive and under settings we pick D and we do a line which is going to now it's just moving the head there and there it is the disc is being read properly now there's an audible beep that comes out of the speaker in here it's kind of quiet so you may not be hearing it but yeah this drive is working great now if I jump to track 40 there it is now it's reading track 40 and let's go to track 70 and there it is also working perfectly now let's take this disc out of here and let's stick this into the 96 track Branch Drive which is nearly the same as 100 and they both have 80 tracks but let's see what happens so I gotta change this to c and let's do a line disc again it's reading but barely here's what this is telling us right now currently the 96 track Branch Drive is on track zero and it says at the very top track zero head zero but the sectors it's reading is not reading all of them it's only reading five of the nine sectors off the disk and it's reading them from track three now we're on track 30 and it's currently reading all nine sectors per track but it's getting them off track 34 what was written to the disk as track 34. and there we are track 73 on this drive is reading the disc at track 7 79 now think about it 100 tracks per inch the tracks are closer together than the 96 track per inch drive so if you overlay them when the 96 track Bridge Drive is on 73 it's actually near the furthest extent of the 100 track per inch Drive okay let's try something else this disc here is formatted just as a normal double density 48 track per inch disc which is drive a so I'm just going to set it to drive a and let's go to a line here and we should be able to read this disc without any issue I formatted this in another machine there it is track zero reads track zero all nine sectors per track and here we are reading track 39 and it is reading the disc perfectly so let's take this disc out and let's stick it into this 96 track per inch drive and it should be reading track zero properly and it is absolutely reading track zero properly now if we hit plus to go to track one which is track one on the drive it's now reading the disk in between track 0 and track one it's still reading track zero and it's only getting one sector but if we push plus again now we're on track two on the physical drive it is now reading track one on the disc that's in the drive because of course it was written for 48 track per inch and now we're running at 96. that's what the whole double step thing is all about if you're trying to read a 48 track per inch disc in a 96 tracker inch drive if you double step you're going to at least be able to read it now remember this drive here is a dual speed drive so if we exit out here and we test the RPM it's going to be running at 300 RPM which is the correct RPM it takes a little bit of time to settle but there it is calculating it's going to run the same exact RPM as these other two disk drives so all three drives when they're reading 250 kilobits per second are going to be reading at 300 RPM which is exactly what I want but the last disc I want to test with this high density disk here so let's reboot out of this and I'm going to pick the four Drive option without forcing 250 kilobits per second because we need to run this at 500 kilobits per second so we'll slide this in pick Drive C for the 1.2 megabyte or 96 track per inch drive and let's do a line now at the top you can see it checking the different bits per second and it's trying 500 and the other ones okay so there it is it's now reading this high density disk this is formatted like a normal MS-DOS 1.2 megabyte disk which has 15 sectors per track which is why it shows 30 there now this is going to be running at 360 or it should be at least I mean it has to be because it was reading it and there it is it's settling in there it is 360 RPM if we go back to this double density disk here this is a 48 track Branch one and we put it in here remember we're not forcing 250 kilobits per second right now and if we go to a line what's going to happen is it's going to figure out that this is a double density disk but you see at the top left of the IMD screen there it's currently set for 300 kilobits per second that's because at least this version of IMD doesn't understand that this is a dual speed drive so when this drive is not getting 500 kilobits per second but it's getting 250 or it's getting 300 it's running at 300 RPM so it's currently running at the wrong data rate I needed to read these types of disks these quad density or double density disks in this drive at 250 kilobits per second foreign disk images you download off the internet onto physical disks the first piece of the puzzle downloading Dave dunfield's IMD disc program which you can just find by Googling image disk and Dave Dave has some good info right here on modifying a 1.2 megabyte drive like I've done here for the Dual speed operation he probably talks about different jumper settings and whatnot here's the download link to image disk 1.19 it's from 2012 and what's really cool is Dave actually has a whole bunch of software and operating system disks in IMD format on his website so none of these require any type of conversion you can just download any of these and make them on a machine like this in fact I'm going to download the visual 1050 system disks from Dave here because I actually need to make some disks for a visual 1050 that I recently got and I'm working on a video for the future for this machine and you can see in this archive here they are all IMD format which is exactly what we want I went ahead and I copied one of the disk images onto this three and a half inch disk from my USB floppy drive it's actually one of the easiest way to get disk images back and forth I'm going to run IMD using the 4 drive and I'm going to force it to 250 kilobits per second and that's because of course I'm going to be using the 96 track per inch drive here and I need it to write at 250 kilobits per second I'm just going to double check the settings so I want to use Drive C that's the 96 track per inch drive it's 80 tracks it's two-sided I don't know if the original image is one-sided or two-sided but I think two is good and we want to make sure the double step is off because I don't want this things double stepping each track we're going to hit W for right here's the disk v1050a now we can see this disk image is made back in 2005 using IMD 0.2 so kind of an old version and while it doesn't mention it here in this description I happen to know for sure that this disk image is an 80 track or I think a 77 Track image so it needs to have a 96 track Branch drive like this now I went ahead and I degauss this disc and I used one of those bulk tape erasers you can find online that's because this was written in a 48 track Branch Drive which has those wider tracks so it could potentially result in some cross talk I don't think it really needs to happen but anytime I switch between a 48 track per inch driving a 96 track range drive with the same physical disc I do a bulk erase on it now you can see it's writing the disk but it's only writing it single-sided now that's because the original drives on that computer must be single-sided 80 track drives and the drive that's in here is double-sided obviously if it doesn't really matter because it's only going to use one of the heads now it goes without saying I didn't really mention the double-sided nature of all of these drives if you go ahead and install single-sided drives on your computer then all you're going to be able to use well are single sided disk images and read single-sided disks so I recommend trying to find double-sided drives if you can although it's not always possible for like 100 track per inch drives like this most of the ones I've ever seen usually micropolis branded are only single sided those are going to work perfectly in this case but you'll just only be able to use single-sided discs as you can see it's up around track 55 and that definitely confirms that the disc drives in the original machine are single-sided 80 track drives or 96 track per inch just like this it's possible and I'm not 100 sure that the drives in the visual 1050 might be 100 track per inch and if I find that this disc doesn't work then I guess I can write it in the other drive here and maybe that'll work now we're going to go to a line and we should see 20 I think because it's 10 sectors per track and there it is it's reading 20. we drop to track 40. there it is 20 again no problems one thing I want to mention about IMD which makes it so extremely powerful is if we go into settings and you see the option full analysis yes what that means is that if you're making an actual disk image every track it's going to look to see if the track format has changed on the same physical disk normally that's not the case most computers use the entire same format across every track on the disk but there are machines that are a little different the trs80 model 1 is a good example of that where track zero the first track on the disk is always FM or single density and if you have a double density controller in the machine all of the other tracks are going to be double density IMD completely supports that you just have to make sure that full analysis is turned on so if you're reading a physical disk into a disk image it notices that one is FM and then it goes to MFM now if you have a physical disk that you want to turn into an IMD disk image and we're just going to take this visual 1050 disk and turn it back into a file put that into your system then you can use this alignment tool to figure out if it's a single-sided disk or not so there it is reading track zero if I push the H key it's now showing question marks because it's reading head one the other side of the disk and that's blank so that just confirms this is a single sided disk we're going to go up to track 70. I want to see how many tracks are actually on this disc so you can see it's reading track 79 which is actually track 80 because the starting track at least in here is zero that alignment option in the main menu there is absolutely essential to help you figure out exactly the disk format of the disk you're about to image how many tracks how many sides and even the original tracks per inch of the drive that was used to make the disk so we need to make sure we configure the settings properly for making this disk image we're going to set it to 80 cylinders which is 0 through 79 for the track numbers we're going to pick one side because we pick double-sided it's going to read the other side of the disk which is blank right now and you don't want that we're going to make sure the double step is off because this drive needs to read every single track not every other track and the rest of this stuff we're going to leave as it is and then we're going to push R for read into file and I'm going to say test.amd and then here's a box you can type a little bit of a description so we're going to say visual 1050 disk test hit escape and press enter and now it's going to analyze the disk and remember I have it forced at 250 kilobits per second right now because I have to do that for this dual speed drive and there it goes it's reading the disk right now and you see it says 10 sectors 512 bytes which is exactly what we would expect 250 kilobits per second notice as it reads the disk here it has an r and then an A and the a is the analysis part and that's because I have full analysis turned on if it was turned off then it would do the analysis once at the beginning and it would read the rest of disk without doing any further analysis it goes faster but I like to keep that option on in case there's any weird disk format changes of the disk that I'm reading that I'm maybe not aware of and there we go it completed it says 800 sectors and 153 are compressed I think that means because those sectors are mainly empty and just to save space in the disk image you create it actually compresses those sectors also sometimes when it makes the disk image it might say deleted data I've found that that's not generally a problem although I recommend reading through the documentation on IMD if you want to know more about what that actually means the final piece of software that's pretty invaluable for manipulating disk images that you download that you then want to write onto physical disks is the hxc floppy Drive software and hxc 2001 this is a floppy Drive emulator and the software that goes with it which is this hxc floppy emulator software right here is incredibly useful for manipulating disk images because of the wide range of disk formats that it supports let's load that visual 1050 IMD file that we just wrote onto this disk here into this software now this loads up right away and it tells us right here it's 80 tracks and one side so that also gives us an indicator of what kind of Drive we're going to need to write this disk some awesome things this can do is we can load up the track analyzer now I happen to know that this is an MFM disk and if we hover over these you see it actually shows the breakdown and I'm trying to get over there it shows the breakdown of the MFM sector now that's kind of how when IMD is doing the alignment function that it knows that it's reading sector from the wrong track if you're using a physically different drive and that's because the sector itself actually contains that track information but you can see the data that's actually contained in the sector right there but even cooler is we can change the visualization to a 96 track per inch visualization and there is the physical layout of the tracks on this disk now visual 1050 discs have 10 sectors per track and that's what IMD was telling us and we can see that visualization right here along with the gaps that exist in between each track now nothing we're seeing in this utility yet are particularly useful but what is very useful is the ability for this thing to load and then save disk images into different formats in this directory I have the actual stream files which were made with the cryoflux archiving system of the Mercure xr4ti Ford car disk it was basically a demonstration disc that they'd give you at the dealer to take home and you could look at all the specs of all the Ford cars and as I mentioned at the beginning of this video with these stream files you can only really write them back to a disk using something like the cryoflux or the grease weasel but you can actually open them in this utility and then we can save them back as an IMD file so there it is it just loaded it up 40 tracks two sides let's look at the track analyzer there's the actual stream data that was read off this disk now if any of these sectors were bad because the original disk was failing or the drive was failing I used to Archive it you'd see all sorts of red marks in here and that's a really good indicator that your disk image that you made at least with those stream files which remember is the actual flux information has a problem with the stream file loaded into this utility I can now say export disk or save as one of the formats this supports reading and writing to is IMD right there and if we pick this and let's save this as a xr4ti I'll just copy the IMD disk image here to the a drive on my USB drive drive and I copied the file onto the hard drive here let's write this onto a physical disk there is xr4ti I popped a disk in there and let's hit enter and this should write this to the disk the hxc floppy utility is extremely versatile for getting disk images for other systems so here are some tracd model 1 disk images I downloaded the file and it's in a DOT dsk format which I think is used by one of the TRS-80 emulators I'm not actually sure exactly how many formats the hxe utility loads but it seems to be very comprehensive at figuring out what things are so if we load this and it says it's an 80 track one-sided disk which doesn't really make sense let's go to the analyzer and it's not actually able to make heads or tail of this disk image here like none of the data is decoding oh wait maybe it's FM oh wait there we go okay it is FM actually taking a look at all these disk images right here blank disk 80 track single sided so I guess for whatever reason these disk images were all created on computer that was using an 80 track or 96 track per inch drive so these aren't ideal because most people are going to have 48 track per inch drives on their trs80 model 1 model 3 stuff like that so you have to find the 48 track per inch or 40 track disk images and write those to physical disks I spent so much time at the beginning of this video talking about all these physical differences with the different disk formats so that when you download these disk images you can try to make heads or tails of what you're downloading so that you know you're getting an appropriate disk image that is hopefully going to work on the end system you want to run it on let's grab another model one disk image off a different site here so this is uh ldos531 I can see that these are also dot dsk files and there it is 35 tracks one sides that is the appropriate size for the original disk drive that was on the model one it was only a 35 track Drive well it had zero through thirty four and that's because physically it just wouldn't go any further past 35. of course if you're using a 40 track drive on there no problem they're both 48 track per inch it's just that a lot of the disk images for the original system are going to be 35 like this let's take a look at the visualization and there we go we can see that this is entirely an FM disk image which is understandable the original disk controller for the model one was only FM later one supported double-sided and MFM and then at this point all we need to do is export this save it as an IMD disk image loaded on this computer here and then it would actually write the image with no problem so there we go I think I'm going to end this video here I know it's been very long and there's a ton of information in here I really tried to pack it in I think it's going to edit together into something that's going to be pretty long but I hope there's a lot of useful information and if you're trying to make physical disk images for your old computers or you're trying to take discs and turn them into disk images so you can archive them upload them to archive.org or share them that this video will prove very useful I've had to leave out quite a bit of extra detail in this video because there's just so much more going on with disk drives but I think there should be enough basics in here to get people started with this process let me know in the comment section if you have questions and I'll try to answer them and maybe do some clarifications check the pinned comment that I'll have at the top of the comment section if there's any information that I'm going to need to add that I forgot to put in this video and it's critical I'll definitely put it in there or maybe I'll put some questions and answers in there as well so yeah definitely check that that out I try I tend to do that on all my videos just as a way to add updates after the fact so if you like this video I'd appreciate a thumbs up if you didn't you know what to do hit that subscribe button if you haven't already huge thanks to my patrons their names are going upside the screen here they get Early Access videos behind the scenes stuff like that I guess that is gonna be that stay healthy stay safe I will see you next time bye [Music]

Channel: Adrian's Digital Basement

Views: 106,926

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Id: fRZVlsxSDw0

Length: 55min 10sec (3310 seconds)

Published: Sat Dec 31 2022