More than two floppy drives?

why does your hard drive get the drive letter C in Windows the answer is because a and B are reserved for floppy drives now based on that you would probably guess that means you can only have two floppy drives in your computer if they reserved only those and while in practice that is mostly true it's not really the whole story my 46th system here now has five functional floppy drives in it with the capability to natively read seven different kinds of disks and thanks to the 40 track five and a quarter inch drive it can be used with archival and emulation software to read even more formats than that now two of these drives are a is it 250 and LS 120 Drive and if you're in the know you'll be aware of the fact that these aren't all that difficult to get working because they're really floppy drives but what may surprise you to know is that the three remaining true floppy drives are all active at once thanks to a four drive controller this means that not only does this computer have it drives at a and B but I also have a floppy drive at E as well I'll get into why it's e later because we need to cover some stuff about the BIOS before that now doing this was actually really easy all I needed to do was plug a card in like this and connect the floppy drives to it and while I will show that later as well I want to first talk about why you even need a special card like this and why it's frustrating that it is special this video is sponsored by Linode and you know it's kind of funny how much time I spend at transferring data onto and off of floppy disks almost 50 years after these came out but these were one of the best ways of transporting data for a long time now though we have much better options like the new one-click install app Leno just added for next cloud Linode offers cloud server hosting that can be used to easily start up a new server using any of their one-click app solutions the newly added next cloud is an open source file syncing and productivity tool that can be used like other services such as Dropbox or Google Drive but setting it up on Linode gives you the option to use their object storage as your data drive this lets you choose the amount of data storage you really need to get your lowest price and if you host other services with them you can use it to easily upload data to use with those that would make the cloud render server idea I talked about an even easier option to use if you want to try out Linode you can use the link in the description to get a free $20 credit now though let's get back to it since the introduction of the IBM PC almost all x86 based computers have been functionally limited to two floppy drives except not quite the original floppy controller in the IBM PC from 1981 did support for floppy drives but not with the internal connector it did so with an external connector meant for two additional floppy drives on the back the external connector was meant for something like an expansion chassis or fully enclosed drive this need for a second connector was something IBM did themselves though there were other computers for around the same time that used extremely similar hardware for their drives and they can happily connect four drives to one cable some of these computers even used identical drives to those in an IBM PC so what's the difference well it's mostly down to the cables when the first three major home computers were released there weren't all that many options for parts so all three of them used floppy drives either directly from or derived from Shughart offerings Shughart had been the leader in floppy drives up to that point and had created the mechanism and interface for the mainstream five and a quarter inch disk the only reason the Apple 2 trs-80 and com pet all use the same kind of disk is because they all used the same drive mechanism however only RadioShack used Shughart interface appellee commoner both bought bear drive mechanisms and made their own interface boards for them so their drives were more customized for PCs we're more interested in looking at systems that use the shugart interface for now early pcs almost all use something like this Tandon TM 100 a or similar Shughart compatible drive this interface became a de facto standard and happened to support for floppy drives much like how ide drives need jumpers for identification shugart interface drives also have jumpers to set which drive ID they're accessed from the jumpers were each connected to four different signal wires to support identifying up to four drives yes it could have been sixteen drives with binary encoding but that's not how it worked the controller's themselves were actually using two pins like that but anyway unlike ide almost no one ever had to set drive ID jumpers on floppy drives this is because all the computer companies all had their own ideas on how to connect floppy drives each with their own limitations apple's custom drives were essentially hardwired and had to be plugged directly into a floppy controller with only two connections you could have more than two drives but you had to have more cards to plug them into Commodores insanely complicated pet drives were different because they used GP to connect their drives the limits were more about the bus than the actual drive interface and if you had other things like printers or shared computers the maximum number of drives you had started to erode away but almost no one would have used more than one dual drive because of the insane cost Tara Sade's implementation was the odd one because it was normal they basically took a standard Shughart interface drive stuffed it in a box so the metal power supply and called it a day you could even just plug them into the drive cable and be good to go these drives do need to have IDs set but you still don't actually have to do it yourself RadioShack cheated in a way and instead of needing to change the ID on the drives they pulled pins out of the connectors on the cable for the ID signals so that drives would only have one possible ID for any position on the cable not quite in line with the standard but close enough that anyone could make a trs-80 drive by stuffing a sugar interface drive in a box with a power supply and as a result of complying with the standard the trs-80 ended up being one of the cheapest all-around options for both consumers and RadioShack they didn't really change this design up until they retired the model for in color computer 3 in the early 90s in favor of making pc compatibles there were other computers that use a sugared interface like CPM machines but I want to bring this back to the PC now while computers that use the standard interface could support having four drives on one cable it was at the cost of only having one wire for controlling the motor on all the drives so when just one drive needed to spin they were all spun not the greatest thing for wear and power consumption this was a fault that most custom interfaces fixed and when IBM saw this while they were designing the PC they decided to do things differently much like everyone else their change though was just to add a twist in the cable this repurposed one of the ID wires as a second motor control the drives themselves were left unchanged much like with TRS ad the twist flips the ID signals in the standard motor signal this does mean that drives received two motor signals but on drives the computer is not trying to use it just goes into one of the open ID jumpers because of the twist on IBM computers all drives are always jumper to ID one so it's always known which jumpers are open and because the drives are identified by whether or not the cable is flipped it isn't possible to have more than two drives on one cable but they gained the advantages of individually powerbal drives without needing to create a custom interface the PCs floppy drive control chip still supported four drives though and had the other two Drive ID signals from the shoe guard interface and if you added a second floppy connector using those and made two more motor control signals you could connect the other two floppy drives that could support now as we saw earlier IBM did add a second connector like this but they did it for external drives because of the size of the drives at the time it wasn't feasible to put four drives inside any home computer and as people use their computers like this it became apparent you really only needed two drives most of the time anyway one to keep your operating system in and one to keep the data you're working on it clone systems that were competing with cost and features like the compact portable quickly dropped the second external connector since that was valuable space for the limited rear i/o later when hard drives were added to systems they became the operating system and data drive for most people because of their immense relative capacity then the single floppy drive left would be mostly used for transferring data and when IBM introduced the 80 they merged the hard drive and floppy controllers they also dropped the external floppy connector for seemingly no reason they did add a new feature to change the address of the floppy controller though giving you the ability to add a second card for four floppy support where you would put those drives in a single Bay 80 though I don't know so clearly even when half-height drives were introduced it was largely seen as unnecessary to have more than two floppy drives even one was sufficient for most applications which is why the PC junior only had one drive as hardware support for four floppy drives was diminished in pcs software or should I say firmware support did as well DOS doesn't actually look for drives itself when it boots up it instead gets a list of available drives from the computer's BIOS the BIOS has to look for and present the floppy and hard drives to dos or else they won't be found later devices like CD drives would come with drivers that would scan the interfaces for the drive they support and manually add them to das as it started but floppy drives were almost always handled by the BIOS as more floppy drives weren't seen as needed the BIOS support for the third and fourth floppy drives went away much like the external connector some much later computers even went as far as and not bothering to support two floppy drives like the Intel board in my windows 98 computer but we can say by the time that the ps2 was introduced for drive support was fully gone and two drives was the norm it's really strange that this support for for floppy drives dwindled out like this IDE is worse with only two drives per controller but motherboard still frequently included two controllers to give you four drives most people probably only needed one hard drive in one disk drive but manufacturers still went out of their way to support four drives I can't help but wonder if the ad came out if IBM had it included the external drive connector as an internal if for floppy support might be more common the manual for one of the four drive controllers I have here specifically calls the second connector an internal connector for the third and fourth drives as opposed to an external because it was so unusual so even though almost all pcs after the 80 will lack for drive support you can add that support back with a dedicated four drive controller like this these really aren't doing anything all that unique with the hardware they just don't omit the second floppy connector and if you're super lucky you might find a controller that can be set to the secondary address meaning you could have eight floppy drives potentially none of the cards I have do that and as far as I can tell it's not that common and it's definitely crossing the line to unnecessary anyway alright I've been holding off on the installation process for long enough it's just kind of underwhelming lis easy here's the card I'm using it is a CA nine to seven 7b advanced super i/o controller I don't see a brand name on it but maybe someone will recognize the logo on the manual I think the only thing I've done to this card is to disable all of the other functions that I'm already doing on the motherboard really all you have to do is connect the drives and plug it into an ISA slot I guess depending on what kind of car do you have you may need to configure jumpers to set your drive types before putting it in and you will need to disable your onboard flight controller if the motherboard has one now the card I'm using here has a dedicated BIOS menu for changing the drive settings instead of jumpers it's not all that different from configuring your normal motherboard BIOS other than the fact that it has this really nice feature that lights up the drives to ask you which ones you want to configure since for floppy support is something that could have been natively supported it doesn't need any weird drivers serve them anything like that and another part of the reason that these are also easy to install is it because any fully functional forward drive controller will have what's called a bios option ROM this is how they restore the missing for drive functionality in the BIOS a more common example of this that you may be familiar with our raid cards which can make many hard drives look like one the biomes now you could try to increase your number of floppy drives by using a secondary controller instead many 16-bit is a multi i/o carts have a floppy controller included and support being set to the secondary address but they don't have an option ROM and I've never been able to get them to work myself and I'm really not interested at making another attempt at it I've sunk a lot of time into that and never gotten close I really don't know how you were supposed to do it with a second floppy controller anyway I've never seen or heard of a bios supporting them and since it was added with the 80 that couldn't physically fit more drives it was kind of dead on arrival there is supposedly extra software that can make it work and I'll link to a page in the description where you can read more about that option but I don't think I've ever seen anyone else have success with that if you do want to try that route find a card with documentation in the ability to change the IQ and DMA addresses without the documentation they're almost impossible to set the jumpers on and most of them aren't scanned and uploaded and you want one with irq and DMA adjustments because the best hope I've seen making them work is a modern bios option ROM that could enable them but it doesn't support shared irq and DMA I really don't recommend this option though and I'll give you a better one than this and what I'm using at the end of the video for now though with this card enabled and configured for my drives the system boots up like normal the fore drive controller adds my additional drive and da start it up recognising it without any additional software or config sis changes now I'm using the card to have a 1.4 megabyte Drive as a a 360 K Drive as be and the last Drive is a 1.2 megabytes right as I mentioned earlier this Drive it shows up as e that's because the motherboard finds the hard drive and then the bios option ROM on the card is run afterwards adding the last floppy drive you can change the drive letters using some dos configuration options but I'm not all that concerned about it and I don't really want it to be C anyway because I would just feel weird but there are no problems with this setup that I've been able to find I can even use disk imaging software with it because it passes through direct access to the hardware just like any other standard floppy controller now mine does to use disk imaging software like this is why I haven't been doing something that I'm sure some of you have been thinking since the start of this video the LS 120 drive I have in this was designed to read new 120 megabyte super disks but unlike the zip drive it is backwards compatible with the standard three and a half inch disks both of those drives connect using a standard IDE interface instead of the shugart floppy interface so I could technically ditch my current a drive and use only the motherboard floppy controller with the LS 120 drive for the extra floppy but the super disk drive isn't as compatible with imaging software so it's really not as useful to me also it's really unreliable and sometimes doesn't work for me so I'm not super keen on using it all the time disk imaging is also the reason I'm keeping the 360 K Drive in the system with the 1.2 megabytes drive the larger drive can technically read and write 360 K disks but 1.2 megabytes have 80 tracks instead of the 40 tracks on 360 K drives the head on a 1.2 megabytes drive is narrower as a result and doesn't write to 360 K discs as well if there was old data on the disk it may only be half overwritten and 40 track drives could see the new and old data tracks as a result I'm not sure how much of a problem this is because I was able to make it work when I tested it myself but I deal with 360 K discs a lot so it's really not worth the risk now if I'm so concerned about disk imaging why don't I get something like a cat weasel or Tyra flex or build a flux engine well I may actually build a flex engine someday I have a definite interest in that but the others are too rare and expensive for me and for right now a DOS PC covers almost everything I want to read and write anyway adding the four drive controller really just lets me add the 1.2 megabyte per plane that short era of games because I was using the 360 K driving here before already and with that I think I've covered pretty much everything there is to know about for drive controllers it's so annoying that for floppy support seems to have just disappeared over time when it really didn't need to now if you see this and want to try and get four floppies in your computer don't be like me and make an old drive controller like this a Grail I'll admit it does exactly what I want but they are hard to find an easier option is to get or build a modern homebrew floppy controller like the XT FDC that supports four floppy drives Serge's floppy board can also be modified to do four drives if you're using one of the pc 8477 controllers and I can vouch that those do four drives since that's what's in these cards both of those cards are also much better options than a secondary controller because the Aeron is hard to add to the BIOS I didn't realize that the XT FDC existed until this video and I didn't know what all was required to mod Serge's card now that I know about those though I probably wouldn't have waited the years I did to get these cards and would have gone for one of those instead well I hope this was helpful for learning about for drive controllers and that you guys enjoyed it if you want to see more stuff like this you can subscribe to the channel and if you want to support the channel I am on patreon but for now that's it I'll see you next time you

Channel: Tech Tangents

Views: 37,892

Rating: 4.9625292 out of 5

Keywords: Tech Tangents, AkBKukU, main, 1980s, floppy drive, four, floppy controller, more floppy drives, floppy limit

Id: ewmHZ-MC0ck

Length: 18min 19sec (1099 seconds)

Published: Wed Jul 15 2020