The Emulex Persyst Colour 2 Vintage Graphics Card 

Glad you enjoyed it!

Yes, apparently I let an error slip through here, thanks for pointing it out.

Someone else noticed this, and it could indeed be the issue. Thanks.

I used a ST-225 w/ RLL for 5 years. The RLL version of the ST-225 is the ST-238. Same geometry, more sectors per track. I also used it on a CMI-6424. The guy who sold me the RLL controller, also said, it was a 640 Cyl drive, not a 614. Got an extra 5/7Mb out of it for a scratch disk. The drives ( MFM 2 RLL ) worked daily with Xenix for more than 4 years, until Xenix died, and I backed everything up and used it as all DOS/Windows 1. MFM was 17 Sectors per track and RLL was 31. They relabel the ST-225Rs IF they format clean with an RLL Controller. I did that, for 4 days. They also label them ST-238 and ST-238R. Unreliable at best is a rumor. I had 30~35 drives - no problem. Finally switched to ESDI, which was another host of problems.

@@joeturner7959 Hi, thanks for your input! I have never had success with RLL on a non-RLL drive. I've had it work for a while, but after a few weeks of use had read errors on several MFM drives. So now I pair RLL controllers only with RLL rated drives.

Thanks!

Definitely worth checking. The drive used to stop working, and only after I moved it about did it start. This could be consistent with what you are suggesting.

You can do that with SpeedStor too and it was free.

@@PCRetroTech Spinrite seems to lowlevel access most MFM-controllers and is trying to "repair" sectors by flipping bits with different patterns. Sometimes, this helps!

It also was able to work with my RLL controller on a MFM drive. I never had an issue with the hardware.

I’ve got one that needs a new home.

Unfortunately I don't have a composite output header for it, so it actually isn't possible to run it on this card. The card only has an RGB DB9 output connector.

@@PCRetroTech it looks like it has an RF pin header. That connector is usually composite video and power, because the RF boxes were external. The IBM 5155 display hooks up there as well. You might be able to acquire an RCA to two pin connector and make it work.

@@jafirelkurd Yes it's possible I come across one of those at some point.

Yes, I think it will prove to be very interesting if we can find out more about it.

Drum memory is just a hard disk, with 1 head per track. Very very fast. No seek times, only rotational latency.

I've never heard of that head bending method. I'm honestly amazed that this works.

@@PCRetroTech Its not from my era, its from the 1950s Burroughs drives, but it worked on a dead ST-4096.

@@PCRetroTech The position of track 0 is defined purely by a mechanical limiter, like a screw or something. The stepper motor uses it as a reference for track 0 and returns there on any read error (and you hear a click). Ajusting the limiter won't be any hard, you'll find out when you open the hdd. LLF required after that, of course. A few tracks at the end of disk may be lost (or not).

@@user-pi4kk5dd3w Interesting. It sounds like a lot of track 0 issues could be worked around this way.

I was going to recommend that as well. The error occurred when it was trying to save the unformat data, not when it was actually formatting the drive. Adding /U will force it to unconditionally format the drive without trying to save the unformat data first.

@@vwestlife Thanks, that is probably correct. I've made further progress which I'll show in the next video.

@@vwestlife Truth be told, every time I forgot to put /U, those unformat info shenanigans felt like I was being punished for someone else's mistake. Undelete was legitimately useful, but I kind of hated unformat back in the day.

Oh, well spotted. That could totally be the issue. Thanks. I actually remember wondering about that at some point, but then didn't bother to check it out.

I noticed this too, seems someone else beat me to it - the controller is obviously RLL, but the drive is MFM; this CAN work but it will be "kind of unreliable, sometimes" when it works. Sounds exactly like your issue. Because your drive is a nice MFM one, it's working well enough that the low-level format took, but there are too many sectors per track for the data to be consistently read accurately. You probably don't need to use an MFM controller, maybe just format it again using 17 sectors per track.

@@shawnmulligan3471 I wondered if that might be possible, but according to the docs for Speedstor it isn't necessarily able to change the settings for the drive. But I'll fiddle with it and see what happens. Obviously there will be a follow up video.

@@PCRetroTech If your controller card supports dynamic / virtual drives, you can set up any geometry you want on the drive. Sometimes you need to set jumpers on the controller to enable this feature. Many Western Digital controllers allow it. Then you use the low level format tool built into the controller - usually, run debug.com, the g=c8000:5 to start the utility. (Might be c800, not c8000 - forget off-hand; use the base io address for you controller card). After low level format, partition using fdisk, and format using DOS format command as usual.

@@shawnmulligan3471 I'll try the format tool built into the controller, though that is what I did originally. I'm not sure why I would have used anything other than the settings for that specific drive though. By the way, I think it is C800:5, though there can be some variations depending on controller.

For the time being I swapped the drive out. I'm reluctant to open them for now.

Yes I recall PCs - even into the Pentium era - that wouldn't boot or even recognize HDDs when some of the partition table data (or other track 0 data) was corrupt and no low level tool would work anymore. Attaching it to an Amigo or MSX with IDE or SCSI interface let me access and fix it easily ...

I've seen these issues before. It's an interesting idea that it might be fixable on a different machine.

The boot sector is all that matters, although with some boot loaders, that’s boot sectorS. The first partition can start anywhere you’d like. DOS’s fdisk is indeed too dumb for this work though. Anyone ever hear tale why one and only one primary partition, and the rest have to be logical? DOS is capable of reading drives with more sensible layouts, it just can’t create them.

That's a real shame. It seems like you've had some really bad luck with those. Unfortunately if the heads got stuck to the platter, then it is all over for the drive. Another thing that can happen is the very fine wires connected to the heads can snap off. I hope it isn't that, but it sounds like something equally catastrophic has happened if two of the heads are completely dead. Of course it is also worth checking for dry solder joints and to see if there are any blown components, if you have some electronics knowledge. Shame about the factory new one. That sounds pretty bad.

@@PCRetroTech Heads snapping off - I would have heard that, especially as they would hit the remains of the actuator arms 2700 times per second... the drive sounds perfectly normal. My guess is bad op-amp or as you said dry joint. Haven't looked at it, it's in the far corner of my tiny museum room where I would need to remove a ton of other stuff just to get to the machine. (there's a pretty recent video of that room on my channel - the more interesting stuff though is my homebrew games) I had heads snapping off happening on an ST157A though... I noticed the motor didn't turn (that was AFTER I replaced a few shorted tantalums). Trying to turn it manually yielded resistance. So I opened it up and tried my best to unstick the head. Unfortunately, the glue connecting the head to the actuator arm had also gone bad and the head pretty easily snapped off. And on top of that, another head two platters down (unreachable) had also welded to the platter and snapped off. Even worse, the owner wanted the files off that drive... but the machine had two identical drives, the other one was about a year older and worked fine and it contained all the files he was talking about.

@@senilyDeluxe Yes, I think you would have heard heads if they snapped off when you had the drive. It seems like your museum is a little like my apartment, so full of stuff that it is difficult to move about. We need to come up with better ways of storing this stuff! I will check out your channel.

Yes, I think that could be one of the issues here. There are others, but I will try this in a followup video.

All worthwhile suggestions, thanks!

@@PCRetroTech Also for calculating the optimum interleave for your HDD-system combo can use The Troubleshooter; you can find it on Hiren`s Boot CD ver 6 to 8. It can help to see if the interleave is varying with the temperature. (Simply extract the archive from the CD and decompress it on a floppy). This program is the best tool to identify what is on your system and also provide tests for everything.

@@sebastian19745 Thanks, I'll look into that.

Sure, but it is the memory which is fast.

@@PCRetroTech Hm, good point -- or should I say hole, picked ~. :) But I will ask: When (video) memory access speeds are being measured, what's really being measured, and would that process still be affected by vendors going from discrete components to ICs? The way I understand it, with main RAM, an address is put out on address lines, and then the RAM chips put those contents on the bus in response. But now I'm talking regular RAM, not VRAM, and I'm not quite sure if there's essentially the same thing again happening on a smaller scale on the actual graphics card, or if there's maybe not even a real difference between RAM and VRAM in that respect, since VRAM is also represented in the system's address space. This is once again pushing the limits of my knowledge, but I just thought maybe it's not a waste of time to ask the above. (Side Q: I guess DMA just allows something other than the CPU to put the address on the bus and read the contents, etc.?)

@@ropersonline They used off the shelf components for the RAM, and clearly here they used very fast (and presumably expensive) RAM chips. I don't know anything about the ASIC, so I can't make any further guesses.

Doesn’t a normal CGA card work with no extra wait states? The snow is caused by giving the CPU priority to access the RAM. So I’m puzzled how on earth the new card can have faster memory on the standard ISA bus. If a normal CGA has wait states, then of course a speed-up would be to design a card with no wait states. Snow can be eliminated by using wait states to hold up the CPU while the video controller accesses memory. No snow implies wait states. Might be interesting to bench test the speed of different CGA cards, unless you have already done this in another video.

​@@migry : You can have faster memory than the ISA bus by sticking some buffers between your card and the ISA bus. Throw in a bit of extra circuitry on your controller chip to control the buffers, and you can have an arbitrarily faster memory speed.

It's amazing that there are programs out there that hit these incompatibilities. I believe the shifting and division instructions may be implemented a little differently, but we'll look into this in a later episode.

@@PCRetroTech Could you write a c or asm program to test the differences between division and shifting instructions between 8088 vs v20? It would be interesting and instructive.

@@jkeelsnc Sure. I plan to take a look at those, and the AAM instruction, which I believe also behaves differently.

I haven't narrowed it down yet, but you can bet it will be the subject of a future video. I'm not actually sure yet whether I just used an undocumented opcode which the V20 is known to not support. I will check and let everyone know in a future video.

Yes, I will do that. I decided not to do it right now as I've done that fairly recently, and I didn't want to throw confounding variables in at this stage.

That's a weird problem indeed. I don't have any idea what would cause that. Nice that you managed to partition it out though.

@@PCRetroTech I think I had to reduce cylinder count in bios.. because even low level formatting locked the machine up when it touched that special spot.

@@procactus9109 Wow.

Not yet, but I may have used SALC. By the way, congrats on the production!

It's probably late enough that it is, but I actually don't know for sure. My guess is home 386 owners would have been after something much later than this. I think even my 286 back in the day had a SuperVGA card.

I think that it won't be a reliable drive, that's for sure. I think I can get it working with the comments here, but whether it stays working remains to be seen. This is usually a very reliable model of drive.

@@PCRetroTech Whatever happens, of will be interesting 😊

Yes indeed.

@@PCRetroTech you could try clearing the bad track list in speedstor and then repeatedly low level formatting that track to see what happens. A different interleave might also help, albeit with a speed penalty.

@@JimLeonard Worth a try, but I've noticed cylinder 0, head 0 often goes before other parts of the drive, probably because it is used very often. Drives that I've pulled apart over the years show why. There's usually a scrape there.

It's worth a try actually. Some of the glitches of the original IBM card actually show up on this card. I might try it later today.

Not yet. I'm still in Germany, but quite by coincidence, I am planning a trip back to Australia this year.

Thanks. Fortunately I do not have any WD40, so no damage done.

I think it is just because there is no picture. Even when I was much younger, CRT whine was not a big deal. It is what we used for TV and computers back in the day and I don't recall there being any issues with the sound. Of course it could also be that the monitor is making an unusual noise because it is old, but this one is in very good condition, so I doubt it.

I’m amazed that it is even audible. I wonder what bandwidth the audio has? Isn’t CRT whine at horizontal sync rate = 15kHz?

@@migry A lot of PC sound systems don't reproduce 15kHz faithfully, so who knows what is actually happening. The microphone wasn't pointed at the screen and it is pretty omnidirectional, so it is slightly surprising something is audible.

On a mic, in a video, through lossy compression that throws away ultrasonics, and through someone else’s media player. Most of us here lived with that whine six inches away from our face every day. You’ll live for 20 min.