Solved! It was a corroded trace near the battery that was causing all the problems.

computerguy08 wrote on 2020-03-23, 21:39:

Solved! It was a corroded trace near the battery that was causing all the problems.

Glad you could solve it. Would you mind posting a couple pics with your fix for future reference?

I've had some issues with auto-detect on an OPTi 495SX based 386/486 board, too, but manual cylinder/head/Precomp/LZ/sector inputs seem to work fine.

The drive does get recognized as a Quantum EL170A during the POST sequence (which should be right), so that works at least. Given it worked fine with the manual settings, I only tried the auto detect option in the bios once or twice and didn't exhaustively try different FSB speeds and ISA divider settings, so it could just be that. (oddly this drive also seems happy with a 10 MHz ISA bus setting, and was only really happy at 8 MHz with the 33/4 and 40/5 settings, with 50/6 and 25/3 both being somewhat unstable)

That old drive also seems happy on a 286 board that I'm pretty sure uses 10 MHz ISA as well (20 MHz PCChips/HedakaCityGate D60 with single oscillator) and goes unstable when I swap in a 50 MHz oscillator for the 40 MHz one. That doesn't happen in my PCChips M205 with separate 32 MHz oscillator and asynch ISA bus jumper select. (though that might just be for the FPU and the asynch ISA setting might use 7.16 MHz instead using the 14.3 MHz crystal, not sure if that Hedaka board has a setting for that)

More on the topic of compatibility: I haven't gotten large disk support of any sort working on any of those board yet beyond C/H/S translation native to the drives. They (including the 386/486) might support over 16 heads, but seem to have the 1024 cylinder limit (the field can accept other values, but a 640 MB drive I tried didn't work right) and that Quantum 170 is limited to IDE PIO mode 2, I believe, so I'm not sure if faster drives (or CF cards) would tolerate overclocked ISA buses better.

That 640 MB drive is another quantum drive, this should be it:
https://stason.org/TULARC/pc/hard-drives-hdd/ … -ATA2-FAST.html

It might not be the 1024 cylinder limit I'm hitting, but a formatting issue since I got that drive with an old Redhat linux build installed on it and reformatted it with MS DOS 5.0. I should try formatting it again, maybe under windows 98.

Now that everything works, I am planning a miniature IBM 5160 "replica" using the setup above. Stay tuned for pics.

aha2940 wrote on 2020-03-24, 00:09:

Glad you could solve it. Would you mind posting a couple pics with your fix for future reference?

Will do this later today.

The build is now fully functional, with DOS 6.22

Here are some more pictures (lots of them):

As you can see, the system does not have a case yet, and the I\O brackets are missing. That is because I am planning to build a custom enclosure, with similar looks to an IBM PC XT.

Neat little system, what's with the wires on the realtek VGA card?

BSA Starfire wrote on 2020-03-24, 23:32:

Neat little system, what's with the wires on the realtek VGA card?

That is how I found it at my local school a few years ago. I can only imagine it was a factory job meant to fix a hardware bug, I don't know.

Made some progress today, shorter floppy cable and custom 3D printed side brackets, meant to hold together the two floppy drives as one solid unit.

awesome project :3
can't wait to see the case

This took a while to create (3D model, get wood, measure wood 4 times, cut wood, sand down the wood), but I think it came out nicely.
It will be the front piece, so it had to be as nice as possible.

The support brackets aren't so beautiful, but it doesn't really matter, they will be hidden inside and they do their job.

I've always wondered about those half height 3.5" seagate drives with the black bezels - what system/case were they actually designed for? Obviously have the XT aesthetic but would clearly not fit in an XT's 5.25" drive bay without replacing the bezel for a wider one.

That looks really nice .

maxtherabbit wrote on 2020-04-19, 15:06:

I've always wondered about those half height 3.5" seagate drives with the black bezels - what system/case were they actually designed for? Obviously have the XT aesthetic but would clearly not fit in an XT's 5.25" drive bay without replacing the bezel for a wider one.

I have noticed the same thing, they look like they are 5.25" full height, but they are obviously narrower. My full height SCSI hard drive has the exact same physical dimensions. I wonder where did it use that faceplate.

I have another ST-157A, no plate on that one though. It looks like a factory plate (has the same screws as the PCB).

The build is now mostly complete, the outer shell is built, only the top cover is missing.

I've tried to get as close to the specs of the 5160 XT: black rear panel, the iconic sloped front panel, internal layout (it turned out to be the best choice by coincidence).

There will be oopsies here and there, because I'm not a professional at this kind of stuff, but I think it turned out very good overall.

A few notes about this build:

- the rear exhaust fan is not working yet, I will have to find another one (the reason why there are two taped wires hanging around inside)
- the floppy drives are way newer compared to the rest of the system, but they had factory black bezels
- the side wood panels are pieces of hardwood flooring, which I got for free.
- the power supply is a heavily modified SFX unit (AT connectors, fan relocated in the front because it wouldn't fit on the bottom, rear switch is also power on switch)
- the many round holes near the speaker are intended for cooling/airflow
- the parallel port is slightly deeper inside the case, because the actual connector is deeeper that the one on the VGA card, which is a bit infuriating; had to use washers and cut the retention screws
- the little switch between the floppy drive and the PSU is actually part of the backup battery holder, which is tucked nicely underneath the floppy drives

I really like that. A glass top would make that look amazing in my opinion. Great work.

LewisRaz wrote on 2020-04-23, 10:28:

I really like that. A glass top would make that look amazing in my opinion. Great work.

I would go with piano black for the top or maybe brushed aluminum, personally .

maxtherabbit wrote on 2020-04-19, 15:06:

I've always wondered about those half height 3.5" seagate drives with the black bezels - what system/case were they actually designed for? Obviously have the XT aesthetic but would clearly not fit in an XT's 5.25" drive bay without replacing the bezel for a wider one.

Could they have been intended for some models of external (probably SCSI) drive bays? Ones for XT and AT class systems might have had that matching aesthetic. (white/gray case with black drive faces)

Today I unearthed my old COMPAQ CRT monitor from the attic to pair it with my build. The wooden planks underneath the monitor are temporary (being the lazy person that I am, they will become permanent 😉 ).

I somehow managed to loose the spacebar on my Laser keyboard as well, gonna have to look for it.

BTW, is it possible to change the monitor refresh rate in Windows 3.1 ?

computerguy08 wrote on 2020-04-27, 19:16:

BTW, is it possible to change the monitor refresh rate in Windows 3.1 ?

Yes, the graphics driver for your video card should give you the option. Otherwise you can use a utility to try force it. I think UniRefresh or VBEHz is one of them.. it may not work on older ISA cards though.