This 8" hard drive doesn't seem to exist (or does it?)

well hello everyone and welcome back to Adrian's digital basement on today's video we're gonna be taking a look at this thing it was saved from the trash and it was given to me and I have no idea what it is and nor did the person who gave it to me the best I can figure out is that this is actually a hard drive and all this stuff you see here is the power supply for this thing so in this video I want to try to figure out if well this is definitely a hard drive see if I can get this thing spinning and perhaps through this interface cable here actually get this hooked up to something maybe we can read something off this thing my hopes aren't High though that this is actually going to work so this may be nothing more than an exploratory video but I figured I'd take you along for the journey because this thing's been sitting on the floor for a while and I figured it's now time to take a look at it so without further Ado let's get right to it [Music] alrighty so the anatomy of a mystery hard drive I have this thing sitting on the 70s towel because the whole thing is extremely heavy and hard to move around but here is the front of the drive and take a look there's actually a sticker with a part number and a serial number on it it appears to be a Japanese brand name hokuchin made in Tokyo Japan part number cd8010p and there's a serial number there now judging by that part number right there I'm guessing that this is an eight inch hard drive 10 megabytes in capacity that would be unformatted capacity whoever owned this before obviously mounted the two power supplies here and this hard drive onto this piece of plywood here the whole thing is extremely heavy it's really actually quite difficult for me to move around obviously in a video you can't tell how heavy something is but I am guessing that this probably weighs about 50 or 60 pounds now it's pretty clear that these two things right here are power supplies we'll take a look at the wiring in a second I think this one here had a sticker on it and it was this one it just fell off perhaps someone might recognize the brand or part number that might be on here but it looks like just a warranty serial number sticker and nothing more on the front power supply here which I've written a little number one on just to help me identify it this has the mains AC input now this is most definitely like a lamp cord or something like that this is not really an appropriate cable for this type of things but obviously this was very homemade the AC Mains cable is just connected right here on this power supply there's a couple lugs there and then from that we have some wires here that go to this AC cooling fan this is 120 volt fan which just blows air across these two power supplies and then there's another couple thin wires that go into this Transformer right here which then feeds power supply 2 and power supply 3. I took a very careful look at all the connections on these three power supplies and there's absolutely no writing as to what voltages they might be they they do all connect to this somewhat chunky rainbow ribbon cable which then comes over here to this harness which plugs into the disk drives controller and has a wire here that goes into this second PCB that's attached to the drive as well I'm forgetting where I recently saw one of these but this appears to be an hour meter that's attached and it goes off to one of the power supplies is this oh okay you can just lift this off here it may not be too easy to read but someone wrote on the wood here with a piece of pencil 2 000 hours March 26 1984. so someone's keeping tabs on how many hours this drive ran perhaps these old hard drives weren't known for their reliability and the more hours you use it the more likely you were to lose your data spinning the drive around take a look at this this is the digital electronics section of the hard drive and actually there are two pcbs sandwiched in here this is an extra adapter board that seems to be in addition to the built-in Drive electronics that is on the actual hard drive the PCB that's towards the camera is what's connected to this ribbon cable here which seems to be a 40 conductor cable and then it has a 50 pin connector on it and it's a little bit lengthy in that this was probably put away from whatever computer it originally connected to now removing this cable here reveals that this PCB here is actually connected to the other PC through a 50 Pin cable and I'll get to what my thoughts are on this Cable in a second in addition down here on the corner there's a little power connector that has a red and a black wire that just goes up to this power harness up here and I have validated that the red is 5 volts and the black is ground and that's very easy to do and you have a ton of TTL logic like this you just look at the red wire if you think that's five volts and check that you have zero ohm continuity to the 5 volt pin on the TTL Logics same for the ground I'm going to try to release the clips to get this PCB off and I'm using a big pen that a viewer sent in it's a big pen with the actual ink removed because this appears to be the perfect tool for this actually whoop with this board off I'll bring it over to the bench so we can use the better camera to take a look at the chips a little closer up and disconnect the 50 Pin cable there alrighty and there we have the hard drives PCB which seems to be pretty complicated as well we have an eprom couple 40 pin dips we obviously have some voltage control stuff over here that might be for controlling the stepper motor that moves the head around or starting the spindle things like that now one thing I find very interesting is this 50 pin connection here there are actually two connections with this 50 pin ribbon cable and one of them has what looks like a Terminator module in it these are resistor packs here and I think what that means is that this 50 pin connection might be sassy s-a-s-i this was the precursor to the scuzzy interface or small computer system interface I can never remember what sassy stands for but I think it might be system attach storage interface either way if it is Sassy that means that it may well be possible to connect this connection directly up to a scuzzy controller because as far as I'm aware Scott fuzzy and Sassy are actually intercompatible well more so that scuzzy is backwards compatible with sassy quartz is not the other way around we do have some dip switch blocks here and here which would imply that maybe this one over here since it's near the connector might be the equivalent of the scuzzy ID setting or The Sassy ID I see down here at the bottom it says main CB or circuit board and then cd8000p 8000 must be the model line of this hard drive and then the name of the company that made this thing now look at this PCB you'll notice that there are these white strips that run up and down across the board I'm pretty sure this was a design to allow the manufacturer to give 5 volts in ground to all the ICS and it looks like bypass caps as well because you notice there aren't very many bypass caps on the board there are some tantalums spread around but generally every one of these ICS should have a bypass cap so perhaps this strip is doing double duty we do have some LEDs like maybe they're Diagnostics or status LEDs there's three there another four there and this large 40 pin package here is Intel or it's an NEC which is Intel 8085 processor and this I see here and here is the support Logic for that and almost certainly this is the boot ROM it was pretty common for hard drive controllers in the 80s to have a hard drive control troller chip on the actual board and then ribbon cables would go out to your hard drive and then you know actually move the heads around and stuff like that that's how MFM or St 506 drives worked but that hard drive controller which is actually usually made by Western Digital started Life as a full-size PCB kind of like this maybe not as many chips as this but it was a full-size PCB and the way the processor communicated with the external board over a ribbon cable is basically the same way it would communicate with that IC controller that's on the hard drive card that might be in a computer so Western Digital took that full-size controller and shrunk it down a typical IC on a hard drive controller would be hooked up to the data bus couple address lines a chip select line stuff like that well it's absolutely no different with those larger PCB based hard drive controllers it was actually pretty common for machines like the k-pro which might not have had a built-in hard drive support only only certain one did to have a PCB made by Western Digital often that would connect to the cpu's data bus and it would be treated just like one of those controller ICS and then out of that card that's in the k-pro would be the connections to go to a normal MFM or St 506 hard drive my hunch is this PCB here does exactly the same thing the 40 pin connection on here is what goes to the CPU it has the address lines and stuff like that it probably follows a similar standard to that Western Digital controller but it may not of course if you're used to the IBM PC with the ISA bus well they took the large Controller made it a single chip stuck it on an Isa card added some support logic and then that's what talk to the hard drive so over on the bench here let's take a closer look at this adapter board or whatever this is now unfortunately it doesn't have any actual markings on it as to who makes it or a model number or anything like that I kind of have the assumption that since it was attached with those clips onto that drive that it was made by the same manufacturer probably as an optional board to interface to computers that didn't have sassy but I'm not totally sure looking on the bottom of the board here we have a Fab marking two zero zero 107 and EC 1283 whatever that means unfortunately that's it for markings on the underside there is nothing more than that just a lot of traces so like that other PCB this also has an Intel 8085 chip we have a couple ROM chips we have a couple static RAM chips these are two one four so that's normal 2K SRAM and then we have one more ROM chip over here and then a whole C of TTL Logic on this thing there are some jumpers on the board they're all labeled W and a number there's another one and there we have two more next to the power connector so perhaps with my viewers eyes on this board people can identify what this actually might be looking at the ROM chips these two are 25 16s and this one's a 2732 so I think with the Retro chip tester Pro I can actually dump the contents of these so I'm going to do that right now alrighty just like that I have gone ahead and I captured the ROMs so I took the three that were on this adapter board here incidentally TMS 2516s have the exact same pin out as 2716s from every other manufacturer for whatever reason Texas Instruments made the 2716 have other voltages that aren't normally on eproms I think plus 12 and -5 so you cannot use a TMS 2716 interchangeably with other brands but the 2516 is interchangeable not sure about programming but at least for reading I also went ahead and I grabbed the ROM that was off the hard drive as well and I have gone ahead and dumped that so let's quickly take a look at those in the hex editor and see if we can see any code that might give some Secrets away to what this board is and maybe what the hard drive is all about here are the files and I'll upload them to archive.org in case you want to take a look at these yourself of course they're 8085 code so they could be run through an emulator or disassembled relatively easily that unfortunately is a little bit above my pay grade my Assembly Language days are long behind me I decided to use notepad plus plus just because it'll be a little easier for us to pick out any strings that might be in here and so far this is the ROM from the hard drive not seeing anything just a bunch of code yeah not much going on there let's take a look at uh let's see which one is the larger one this is the larger one here this is the 2732 that's on the adapter uh not seeing anything neither nothing at all just a little bit of padding at the end of the ROM and then this ROM here this doesn't seem to have anything in here except maybe like a lookup table or something like that don't think that's actually program code and the final ROM here it is uh seems to be random enough to maybe be program code although I don't think so nope nothing there either so nothing revealing in any of these four ROMs like I said I'll upload these so maybe someone else can pick something out of these okay so the next logical thing I think I need to do is start doing some research to see if I can figure out if I can find any information on that hard drive whatsoever I'd like to know if it is Sassy for sure and I'd like to know what the power connector voltages are and the pin out it's using a normal like amphenol type power connector that was pretty common back in the day eight inch disk drives use the same one but I did a little bit of poking around on there and it does not appear that it uses a standard pin out I think I can figure it out for the most part but I'd like to find some documentation if possible so after searching I found absolutely nothing I could find evidence that hokushin was an actual hard drive manufacturer like they they made hard drives but I found nothing specific on the CD 8000 which is what's marked on the PCB or the cda10 which is what's written on that sticker on the hard drive this Wikipedia article on defunct hard drive manufacturers does list hokushin electric works as a company let's check the citation and here's the article it's talking about a parallel Trend between Japan and Europe I guess doing hard drives maybe NEC Fujitsu Hitachi Toshiba all entered in the mid to late 1960s and then 1970s old Japanese companies attempted to Market disk drives to non-japanese customers in the US market until then the size of the market for the Japanese computer limited the market size of their drives a smaller domestic Market also meant fewer independent Japanese Drive companies entered in the 70s as alternative sources of Supply namely Mitsubishi and hokushin electric works I did find this this which seems to be a patent taken out by hokushin for a hard drive but I did look at this quickly and it appears this seems to be like a five and a quarter inch or maybe even a three and a half inch hard drive that is MFM or St 506 based definitely not this there is one reference down here in the document hokushin electric Works limited CD 8000 expand your system versatility with a low-cost eight inch Winchester from 1980 CD space 8000. so I am putting out a call to my viewers can anyone be a super sleuth and maybe find a little bit of information about this CD 8000 line more than the couple things I just found it'll be pretty helpful but okay let's get back to it let's see if I can figure out how to power this thing up so I took a close look at the power supplies and the cabling that's on there and I tried just to use some logic to try to figure out what is what on the piece of paper here I've written everything that's on the actual drive itself so that's the connector that goes into the PCB on the drive that has color-coded wires that are going into it so we have these 6 wires then there's that little pigtail harness that then has the ribbon cable or that multi-color rainbow cable that goes off to the power supplies and that is these wires here some of them are combined like black and brown red and orange purple and yellow and blue and green there's a not connected pin this green pin on the drive is not connected and then also there is a white and gray on the psus remember there are two major PSU units but one of them has two little boards inside so I'm calling that uh two and three and then the big one is PSU one so PSU one has the blue and green and the purple and yellow thick wires going to it and then psu3 is the easiest one to figure out it actually has four connections on it but it seems that two of them and two of them are parallel together but I can easily determine that that power supply is grounded five volts because again as I mentioned I can trace the five volt connection on the power supply all the way to TTL logic chips on both the PCB on the hard drive and also on that adapter board so I know for sure the black wire on the drive is ground and the red wire is 5 volts absolutely for sure but then that leaves us with three other connections I was able to determine by looking at the PCB on the drive the actual solder connections that this blue wire which goes to the blue and green which goes to that large power supply is also ground it is actually common on the PCB with this ground up here so that leaves us two connections one of them goes to the large big chunky PCB that's on there and I'm going to guess that that is 24 volts that goes through the purple and yellow wires so they're common together and then it goes to the yellow wire connector that's on the drive and then there's one more pin that is connected it's connected on its own to a small little power supply which the ground wire on that power supply goes off to the ground wire one of the adjacent ones but has one wire that goes to the drive it's this white wire which goes to the gray on that Ribbon or multi-color cable and I think that's minus five volts the reason why I think it's -5 volts is typically -5 volts is just a bias voltage so it's very low current and the power supply that is hooked on up to the actual physical power supply on the on that unit there is really little and yet the really big power supply which is giant is probably giving 24 volts which is going to be used for both stepping the heads and turning the spindle I did a little reading of some documentation I could find on eight inch hard drives from back in the day and they used either 120 volts to turn the spindle motor and 24 for the stepper or they just use 24 volts entirely to run both the spindle motor and the stepper together now what we're looking at here is the actual pin out from the sugar sa-1000 which is also an eight inch hard drive it uses the exact same physical connector as this drive well unfortunately that doesn't match because I've already determined and without a doubt that pin 1 is ground and pin 6 is ground on this drive I mean there's actually ground traces running right to those pins but if we take a look at the sugar sa-1000 right here it's pin one goes to 24 volts DC plus 24 volts DC so clearly it's a different pin out so I can't really rely on that but I can rely on the numbering of the pins because that's actually silk screen onto the PCB so I know that pin one is in the same position as this image right here so that leaves me with this as the idea of what we have I just added these in so 24 volts looks to be on pin two I can see a thick thick Trace coming from the connector going off to another connector on the PCB but I can't see unfortunately it goes to pin four because it appears to be on the back side of the drive or it's just not connected at all could be that too I think arm with some basic knowledge here I think the best thing to do now is unplug the power cable from the hard drive and power up those really really sketchy power supplies there's not even like a fuse on there or anything so I better use a power strip so I can turn it on and has a circuit breaker on it in case everything goes bang all right it looks sketchy but I have three multimeters connected this one is here as well I'm expecting that this one is five volts that's going to be 24 volts and this small one here is going to be the minus 5 volts I have this whole sketchy assembly here connected to a power strip right here with a switch so we'll turn that on in a second and I do have the power connector disconnected from the drive so that's where the multimeters are connected I have no idea if this thing is going to work or smoke or what but I did give this a quick once over and I don't see anything that's like shorting or that should be bad everything seems to be firmly connected properly etc etc so I think here we go okay five volts okay minus 12 12 volts on the one I thought was minus five so that's actually minus 12 and we are not getting anything on that one okay let's turn this all off now one thing by the way is you don't want to necessarily start old switch mode power supplies when you don't have any load on them but these are both linear power suppliers it's a giant Transformer right there and there's another one inside this metal cage here so basically the Transformer takes 120 volts brings it down to something lesser it goes through a bridge rectifier it goes through some smoothing caps and then it actually has a voltage regulator which is almost certainly what's underneath these two covers right here and then there's more on the back of this board there are the large package ones and they're using this large metal case here as a heatsink which is why this fan is blowing air across this stuff they get very hot they're very inefficient but they have a nice smooth and stable output but at least they seem to work fine at zero load while switchmo power supply depending on the type especially the older ones need some kind of a load or they can get damaged specifically they can run away the voltage can get too high and it can damage the output caps and stuff like that but this seems okay except we weren't getting anything on this multimeter so let me just double check my connections and I'm also going to update this sheet here to reflect that the minus 5 volts is actually minus 12. all right I just had a realization of what's going on the big power supply is the one I wasn't getting anything out of I just realized that the ground output of this is not connected to these power supplies right here it is connected together once it's plugged into the hard drive it's actually bridged on the PCB but the ground lines are separate so I'm going to clip the ground for this multimeter right onto here which I think is the ground and then this should be 24 volts so let's hit the power switch oh there it is 24 volts okay as sketchy as these power supplies are I don't know what the Ripple is going to be like but clearly they're all generating the right voltage rails wow okay that's really quite cool that is actually one of the beauties of these linear supplies they're so simple there's no oscillators or controllers or anything that can go bad the capacitors only are doing smoothing and that's pretty much it so I probably should switch these things over to AC and I'll just quickly double check the Ripple on the output of these make sure that it's giving a nice smooth output and I gotta say under no load conditions I'm not really seeing any ac voltage on these at all now under no load is like the easiest possible condition because as you load up these linear supplies you'll get more Ripple it's just how they work but the Caps seem to be doing some kind of a job right now so I'm going to say that they are not dead at least so I think at this point what's left to do is plug that power connector back into the hard drive and see if that thing even spins if it doesn't spin obviously there's nothing more we can do really with this video but if it does maybe I can hook it up to a computer and get it to do something how cool would that be one thing I do want to do is take this fan off here this thing is way too noisy it's nice that it works but the fact is if you stick your finger in there chop chop and of course uh it makes a real racket if I ever were to try to use this hard drive actually use this hard drive I would install switch mode power supplies on here you just need to get one that's five volts 24 volts with that minus 12 volts and then uh you know we should have a much more efficient hard drive not that not that I ever be using this thing in Earnest so to be honest these uh these large ones probably would be fine but yeah there's that fan it's uh it's chunky it's really chunky all right power is reconnected and I have connected up to the 24 volt power supply on this multimeter and this one is the 5 volt power supply right here I'm not going to monitor the minus 12 because it's not as important it's just a bias voltage so let's see what happens when we turn this on is the Magic Smoke going to be released or what here we go okay drive's not doing anything but we are getting 5.1 volts here and we're getting 24 volts there oh I heard the drive click so unfortunately there's some stiction going on in there nothing but when I turn it off there's a click hmm do I need to try to beat this drive to get it to spin or is there just some kind of fault with it and that's why it's not working definitely it's getting the voltage it needs but it's not attempting to spin but yeah when you turn off the power there's a little a little click sound oh let me check out the status LEDs on the side here all right well the couple of them are on but that's it now I've added the clamp meter to the purple and the yellow wire which is the 24 volts positive and it's set for DC 10 amps let's see if this drive is drying current yeah it's about 200 milliamps obviously that's not enough to spin the hard drive so it's quite possible that this drive well maybe it doesn't spin up until it gets a command to spin up so perhaps I should try hooking up this controller board here which maybe will command the drive to spin up and let's see if that makes any difference alrighty let's give it a try now voltage is pretty high 5.39 volts on the 5 volt rail 24 volts is just fine is a bit on the high side though for the five volt rail I do not like it at all and there's certainly no signs of life I mean other than those status LEDs hmm well it's a few days later and obviously with a wardrobe change that's obvious and I have spent some more time investigating this drive and I guess I figured some stuff out unfortunately nothing is particularly good news one thing I have figured out for sure is that the spindle motor on this which is attached to the disc itself is not stuck I was thinking that maybe it was trying to spin up that motor and because it was stuck it just wasn't doing anything we didn't hear anything although that current draw we saw on the 24 volt line was a little bit too low to make sense that that was actually happening but you never know maybe it was trying to really low current initial Spin and then it would ramp up to speed up the spindle the way I know that the spindle actually can turn I can't show right now because we're going to have to take the drive apart a little further than it is right now but down in between this metal plate here and the hard drive there's actually what looks like a rotary encoder it's a disc with notches in it and obviously there's a hall effect sensor and that's used by the drive Electronics to figure out if the drive is spinning or not the wheel with The Notches in it is fully exposed not encased in anything so I can just stick a screwdriver down there and gently move it back and forth and I can feel the weight of this spindle turning as I move it so that means there's a few possibilities as to why the drive is not spinning one is of course that the driver Electronics does have control of whether the drive is spinning or not and it hasn't even tried to spin the drive next is the motor control Electronics may be damaged so potentially the processor or whatever circuitry does control the motor is telling it to spin like it's sending the different phases through the transistors and there's something wrong there so it's not getting to the motor and finally the most unlikely thing is that the motor itself may be damaged I think the best thing to do at this point is take this drive off of this wooden plate so that I can remove this metal cover here which should expose the spindle motor and I can see Electronics on this metal plate it's like a heat sink here that are almost certainly for driving the motor with the drive removed from the board that's actually exposed to branding and writing on this power supply this is the Dual voltage one it has 5 volts and I think minus 12 on it this power supply was made by power one Incorporated in Camarillo California it's an hcbb-75 watts output 5 volts DC at 6 amps there's overvolt protection and then also has plus and minus 12 volt DC at 1.75 amps or 15 volts plus or minus 15 volts that is at 1.5 amps anyhow there is the side of the hard drive that we weren't seeing there is unfortunately no writing of any kind on here but there are Phillips screws that should remove this plate and underneath here like I said there are Electronics that's what these uh cables here are connected to that are surely used at least for the spindle motor and maybe for the head assembly movement all right hopefully the camera is focusing so this is the encoder wheel that I was talking about in fact there's a hall effect sensor right there and this is attached to the spindle and I can turn this it's definitely connected to the spindle because there's a lot of mass behind this as I turn it so those are the discs inside the drive that are moving back and forth you see this thing under here this is the actual spindle motor itself and it looks like there's a bunch of wiring right here that goes to the various windings in there and this is a smaller lead which is maybe some kind of a speed sensor or something like that although obviously with the hall effect sensor you wouldn't think that's needed but maybe it's some kind of feedback or something like that and now we're looking at the back side of the plate that I just removed this is that cover that had those three screws in it and look at these large resistors here there's two of them these large resistors are almost certainly used for power regulation there's a bunch of transistors which I haven't shown yet that are on they're attached to this board here and it probably shunts the extra current through these to bleed that off and lower the voltage down let me disconnect these two leads here I think I can open this up more so we can get a better look at the board there so there it is hokushin PSD power supply device or PSD I don't know what that stands for circuit board is CB we have a nice chunky relay here I would assume that this gets energized to actually spin the drive spindle and the fact is we're not even hearing a click from this so it kind of implies that there is no command or anything being sent to this board to actually engage the spindle motor this is where service documentation for this drive would be extremely helpful because we could get an idea of how it's actually supposed to work notice right here there are wires that are going through sort of a Silastic looking seal this is certainly for the head stepper motor assembly and I guess the head read write signals as well and all these cables on the top of the drive here go from this PCB and these other things to these connectors here which is how it interfaces to the main PCB except for this wire right here which I'm assuming is going to be the 24 volts and that comes right off the main PCB right by the power connector here you can see the traces for 24 volts go from this connector over to a little header here which then goes to this wire which makes its way to this PCB I am going to reconnect these cables which incidentally had a very nice firm connection and there's no evidence of any kind of corrosion or anything on this drive so I don't think our problems with it not spinning are due to something like that but I'm going to put this back together so we can power this thing up and I want to do a little bit of probing around with an oscilloscope I have the drive on the bench with its circuit board facing up because I wanted to probe this a little bit with an oscilloscope to see if it's even executing code but before you do that though I want to mention that I edited together the footage that I've shot so far for this video and actually released it to the higher tiers on my patreon page because I thought maybe some of the smart people there would be able to reverse engineer some of the ROMs that I had jump for this or even do a little sleuthing on Google to find some more information on this that I might not have been able to find let's take a look at some of the information that my patrons were able to uncover the first message is from the Retro Retro guy and it says hi Adrian I found this one on the UK eBay site and it's for the same model of hard drive and he put the link here to the listing and unfortunately Even though three days ago this link was actually working and I could see pictures of someone trying to sell a New Old Stock one of these hard drives I had meant to save all the pictures that were on that listing because there were several unfortunately I didn't and they're gone now there wasn't anything super revealing in the photos luckily it just showed a box for the drive it was like in the original packing materials and the drive that was being sold by that seller didn't have the additional host adapter on it just had the single Drive Electronics PCB there were also a couple certification papers that said that it was QA tested stuff like that but there wasn't anything particularly revealing when looking at the pictures of the drive it didn't have these little standoffs on here that are on mine to hold that extra PCB and it also didn't have this little thing as well the next comment is from Patron Starlight Monaco and they said they weren't able to find any information on the drive itself but they were able to figure out that hokushin electric Works limited merged with yokogawa electric corporation in 1983 and there's a reference to a Japanese web page here they went on to say that they could not find any information regarding the drive archived on yokogawa's website and it didn't look like yokugawa published any of the archival information from hokushin before the merger that could be also why there seems to be no information whatsoever anywhere on the internet about this drive and lastly a few patrons are working on disassembling the ROMs or on the drive and on the adapter board and Peter goes on to say that the dump I made for one of the ROMs on the adapter board which is currently not installed on here it's sitting over there looks like it was wrong like it doesn't seem to have any program code or anything like that Peter says that the ROM that's at 11k on the adapter looks like it Maps into the start of memory space and incidentally the 8085 starts executing from ROM right at the beginning of address space this is different than say a 6502 which uses ROMs that are mapped up to the top of the memory space and that's also the same as the 8086 which uses the ROMs that are up at the top there's a jump Vector that's contained in a fixed location up in that ROM space and the CPU looks for that when it's powered on and then it starts to execute code from that location that's referenced there Peter says that that ROM seems to indicate that it's looking for code to be mapped at 2000 to 2 FFF which Peter thinks would be 12 e and 12K but of course 12K was the one we looked at in the hex editor that just had a whole lot of zeros and 80s and stuff like that didn't look like actual valid code of any kind so Peter asked me to go check to make sure that I had a good dump of that so I did I went and stuck it in both the Retro chip tester Pro and in my mini pro the more updated version which is sitting right here and I got an identical dump from that chip multiple times in both of those readers well a patron Cola Holika read my reply there and thought that maybe that particular eprom was just used as some kind of like lookup tables or combinational logic it wasn't actually used for executing program code in fact the 12E ROM chip which is the one that's potentially problematic is this one right here which is nowhere near the the two ROM chips that are by the CPU so it kind of makes sense that this is some kind of combinational logic well doesn't make sense but the fact that it's over here on its own kind of makes me think that it is a combinational logic and then here's a comment from Cola holiker again it was on the same thread talking about the ROMs they asked if I could power this board up and check the chips like line on this chip here the one that has the the funny dump to see that if it's selected all the time and if it is that means this is used for like combinational logic kind of like a pla or something like that and not as actual program code so I think it's time to power up this drive poke around a little bit on the main PCB and then I'll power up this adapter here I'll connect this up and then we'll poke around on these chips as well and see if we're seeing evidence of any program code actually running potentially as well I can probe the signaling that's going to these pin headers here which are going to those cables that go to that power board maybe we could see some evidence of the square waves that are used to drive the motor alrighty so on the main PCB we have the CPU this is the 8085 CPU we have this which is the 8155 it's like a programmable timer and also has 256 bytes of SRAM static Ram so that is used by the CPU and then right here of course is the programmer on for the CPU so this will be mapped into the start of address space and then this here is an 8255 which I think we looked at earlier in the video this is like also used for programmable interrupts or timers or something like that so the power supplies are still connected here to the drives through this rainbow cable and the sketchy AC power cord is still connected and it's hooked up to the power strip right here so I'm going to turn this on and I can see status LEDs on this drive as well oh incidentally remember how when I had the two boards connected the five volt rail was like too high it was like almost 5.4 volts I was actually able to turn down the 5 volt rail on the power supply here there's actually an adjustable potentiometer on there so with the drive powered up we have the status LEDs and if I turn it off we get the same click we were getting before and we can turn it on and hopefully you can see these status LEDs there's a little bit of a change this one was on and then it goes off and yeah that's it the drive is not doing anything alrighty so we're on the CPU on the five volt Rail and I haven't seen this like weird pulsing that is happening on that rail so I'm not so sure that this uh power supply is actually working properly so I'm going to break the five volt connection here and I'll use my bench power supply to power this up because uh that just doesn't look right and that that rail's got to be good otherwise glitching on there that could have unpredictable results alrighty the bench Supply is connected uh let's power this up without any other voltages and just see what it does well we're getting a nice smooth five volts now no more Ripple on there so that's good so let's turn that on and then turn on the rest of the power all right so now we have both those LEDs on we're getting two amps on the 5 volt Rail and actually what's interesting is that pulsing is there now when I have 24 volts turned on is there some kind of like lack of isolation here or a short on this board so that is a bit strange so okay there was nothing actually wrong with that particular power supply so I suppose I can just hook it back up again hmm okay sorry I doubted the five volt power supply that is reconnected let's just see if this is behaving the same way yes it is exactly the same check the voltage 4.93 volts okay enough talking I'm going to turn the power on let's take a look at the CPU so I have the pin out right here we got clock signals here on pins one and two and there it is 3.6 megahertz which I guess is the clock frequency of this CPU we're now looking at the reset line pin 36 reset in so remember it's reset low so when it's low the CPU is in reset if I shut the power off and when I turn it on it should stay low for a second then go high yeah and it did it just for a split second it was low and then it went high so I'd say that's normal behavior but you can see that little pulsing that's going on I think that's that Ripple that comes and goes very unusual what's happening there looking at the address and the data lines on the CPU like is typical with Intel they're multiplexing the address and the data bus lines at least zero through seven the rest are independent which is why you see them there okay I'm on address line zero well it's address and data bus line and zoom out that looks way too repetitive for normal operation but could be stuck in some kind of a loop yeah you see how it looks a little different initially and now it's just stuck in a loop let me try a different line here we should see a little bit of activities that's executing ROM code it may be stuck in some kind of a very tight Loop cycle trying to run the motor or something like that and here we are on just one of the address lines itself that the non-multiplexed ones and yeah you see a little bit of activity and then it kind of falls into that repeating cycle that looks okay though I don't think that's a problem we don't know how this is supposed to work but I think this is what's going on here I'm on the chips like line on the eeprom and you can see that it's selecting the ROM just ever so slightly and that would be normal if it's executing code out of it but if we turn it off and we look at it when we power it on you see some more activity before it settles in again normal so definitely seems like to me this thing is executing code properly off the ROM they might be trying to spin the drive it might be waiting for a command over the interface connector here it's hard to really know I'm going to probe the pins here that go to that other board let's see if we see anything that looks like maybe motor control or something like that and that was it nothing really interesting on any of those pins that go down to that other board so that sort of applies to me this PCB is not even attempting to spin or turn the spindle here which I guess is not totally unusual obviously we're used to hard drives as soon as you power them up they just immediately spin but definitely Enterprise type drives need a command to start spinning and they do that because if you have like 10 drives you don't want them to all spin simultaneously you'll want to spin them up in sequence because you might overload the power supply spinning up a hard drive takes a lot more current than just running at steady state so you want to do them in sequence there are a bunch of test points on this PCB so I'm just going to probe them all just see if I see any interesting signals on any of them unfortunately probably around those different test points did not reveal anything at all let's take a look at this uh Terminator thing here so I originally theorized this thing was sassy here's a close-up picture of the Terminator and the thing is that makes me not believe that this is sassy as you can tell here that there are signals on all of these wires these are terminating resistors they essentially have five volts of ground going to them and then there's a 2 or 330 ohm and a 390 in this one and this one's got a 220 and a 330 which doesn't even make sense scuzzy uses I think 220 and 330. it basically floats the lines around two and a half volts and then they can either go to five volts or they can go down to ground well this 330 and 391 doesn't really make sense to me but the worst thing is is I think there's ground on pin one here but the rest of these have signals on them which is not at all how Sassy or scuzzy works also the 5 volt termination Power Pin is on a different pin than the scuzzy standard which I think is uh 32 maybe I can't remember off top of my head but yeah this this it doesn't seem right at all there's a bunch of pins that aren't used at all or they're not terminated at all so yeah I don't really know what's going on with this signal this is obviously something custom which I don't think is totally unusual the Japanese computer and also the Japanese electronics Industry seem to do things kind of on their own a little bit like transistors that are Japanese Parts have a different pin out than the normal ones that were in use in the US bringing up the oscilloscope and looking at these pins they are floating 2.2 volts but they're not really doing anything let's cut the power and turn it back on let's see if we see anything like activity wise on here no there's really nothing going on alrighty let me uh put back the adapter board here and we'll connect this up and we'll see what we can see on this thing oh before I do that I need to connect the 50 Pin cable which is floating around on my bench here all right as you can see the adapter board is back on I have the 50 Pin cable connected and I'm just checking the power I'm getting 4.7 volts or so on the CPU on the adapter board so I think it should be running properly ah take a look at this so I'm on the one of the pins that are on that 50 Pin cable and there's absolutely a communication happening right now between the adapter board and the other one the voltage is a little bit lower but that is interesting that there's something going on let's check the other pins here so they all seem to have a signal on them it's hard to probe because I have to kind of go on the Terminator below let's reset the drive by shutting the power off and on wow it's like instantaneous that it actually is communicating that's interesting let's look at the signals on the CPU so let's see here pin one that's the clock we have a six megahertz oscillator on the CPU here on the adapter board it's a little bit faster than I would have thought let's check some of the address lines I'm not sure this thing is actually running any code right now at all now I stand corrected it does appear to be doing something on here actually these are address lines and we have activity so I guess it's running code I don't know and we're on one of the ROM chips and I think this is Chip select here so uh if I recycle the power yep there's some activity and then it settles into just this occasional activity so it could be it copied stuff into the RAM and it's running it from Ram you know it's who knows exactly what's going on here I have the pin out for the 2716 which is the ROM chip here the mystery ROM chip that has the bad code in it let's just see if uh pin 18 and pin 20 are low all the time or high all the time for that matter all right on pin 20 it's high all the time this chip is not being accessed whatsoever and then looking at what are the data bus lines on this chip there's no activity so this is definitely not connected to the data bus this chip is used for some other function that currently isn't actually happening it could be something to do with like the host interface maybe some kind of translation or whatever that happens but the fact is it's not being selected right now we're not seeing activity on the data bus lines in fact if we look at these other two chips over here we should see plenty of activity on the data bus lines and yeah we do which is correct because uh they are shared with the CPU they are talking to the CPU turn it off and on yep we see normal activity but on this chip over here those pins they're all just low so there's whatever that chip does it is irrelevant to the CPU so I don't necessarily think that that ROM dump is bad it's just used for a purpose that we don't fully understand well that is going to be it for this video I know it's probably disappointing to people that I couldn't get this drive at least spinning I'd like to hear what it sounds like but it seems like well it's not even trying to spin that drive that spindle is just not doing anything I'm not going to say all hope is lost for us hearing this drive work maybe if some information is found like datasheet service information anything might help us understand it a little bit better and maybe with those ROMs which have been dumped people who are experts at 8085 assembly can disassemble those and figure out a little bit about how this works and the pictures might help as well unfortunately one of the things about the disassembled code in the ROMs is that we we still need to know how all the i o ports work if there are i o ports which the code can then hit to then spin the drive for instance we don't know what those are without schematics the idea of reverse engineering this drive it would be a massive massive project I'll just throw this out there if you're local to me here in Portland OR the Portland area and you want to get this drive in your hands because you think you can maybe reverse engineer how this works definitely hit me up send me an email to the email address that's in my Channel about page the com I might miss comments if you put it in a comment so definitely send me an email and then you can come get this drive and maybe figure out how it actually works one thing I want to add as well is I theorize that this adapter board is maybe an emulation of the Western Digital 1001 adapter board that was very common back in the very early 80s and I think from a time period perspective it's possible the Western Digital board came out I think in 1980 and while this drive might have come out in the same time and in that case I think it's kind of unlikely that it emulates the Western Digital board I think it's more likely it's emulating or it's following some kind of a standard that was used on Japanese hard drives from the 70s that's probably more likely and maybe those if anyone can find the standard stock and we can figure out how to interface to it maybe there's a command that can get this thing spinning anyhow check out the high-res pictures uploaded to the GitHub repo download those the traces should be very visible all the ICS are visible I know without removing all the chips you can't really tell what's connected to what but it's possible that some reverse engineering could be done from those pictures along with the dumps of the ROMs and stuff like that so anyhow disappointing video but I think interesting nonetheless it shows that there was a whole bunch of Technology out there like hard drives that all the information on it is just lost to time as my Patron pointed out this company was basically belly up while it got absorbed by another Japanese company in 1983 which was was just two years after this drive was made so we don't really know how long hokushen was actually making hard drives the company probably been around for a lot longer making other things there's actually evidence that they made projectors and other types of equipment but the hard drive arm of them might have come and gone in just a few years got absorbed by that other company and then that was that so that's it we're stuck I think I'll give it a few weeks of this video being live and then uh maybe I'll do that disassembly video on the second channel so anyhow if you liked this video and found an interesting thumbs up if you didn't you know what to do thanks to my patrons their names are scroll off the side of the the screen here of course thanks to them who already helped me out on figuring out a little bit more information about this thing and uh yeah subscribe all the usual YouTube stuff and that is going to be that so stay healthy stay safe I will see you next time bye foreign

Channel: Adrian's Digital Basement

Views: 253,505

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Id: R6bSOTaYH9Y

Length: 49min 32sec (2972 seconds)

Published: Sat Dec 24 2022