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Breathing new life into 1981 IBM 5150

VERAULT

VERAULT

Veteran Member
Joined
Jan 30, 2012
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Location
Connecticut, USA
So I have a 16KB-64KB IBM 5150 board with a BIOS date of 10-1981. I picked this board up for a really good price as part of an Apple /// haul from a couple years back. I have the early 2 screw Chassis and black PSU and one 160KB dual height floppy drive to complete this setup.

Anyway the board had a short on the 12v rail. Bad tantalum of course. Drive also had a mangled variable capacitor I opened another thread for: https://forum.vcfed.org/index.php?t...t1-trimmer-pot-for-5150.1239183/#post-1264720

I replaced all the tantalums and the board still has no life.. just a very faint high pitch squeel like a key is stuck down (no KB connected).. but very faint.

Always check the obvious! Can you spot the glaring problem I completely missed over 2 days? IMG_20220713_133615.jpg

Just south of the p9 power connector you can see the new varial cap I installed.

So according to minus zero degrees this boards bios limitations cannot see other boards bios. So my vga card doesnt work and I am verifying post via a janky composite video connection. And since Alt bios' wont work how will I get XTIDE to work on this system?

So far its running on 16KB ram, I need to populate the other banks but we are getting there.

The speaker is still outputing horrible high pitch noise.. I can hear the post beeps but the squeal is constant.. What should I be looking for?

Also to repair the problems pointed out in the photo.. for those who saw the problem.. I had to pull some AT PSU connectors from a 5160 board to get this thing up and running. Where can I get replacement AT psu connectors?
 
And since Alt bios' wont work how will I get XTIDE to work on this system?
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Only by upgrading the BIOS. Later versions for that board do support option ROMs.
 
Timo W. said:
Only by upgrading the BIOS. Later versions for that board do support option ROMs.
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I want it to be an example of period correct early 5150, but with ease of use. Guess thats no possible. Can I even use an MFM HDD controller with this bios?
 
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Wow so this machine at best can only have two floppy drives and thats it? Huh? Its essentially useless as far as useability is concerned. But the floppy controller can do both 160kb and 360KB floppy drives?
I got to think about this.. If thats all true, and I am sure it is, it wont be much fun or use like that.
 
VERAULT said:
I want it to be an example of period correct early 5150, but with ease of use.
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I see. But I would guess many, or even most owners back then later swapped in the 1982 BIOS anyway. It would still be period correct.

Or maybe you can swap the BASIC ROM with the XT-IDE ROM? Not sure if it can run from 0xF600.
 
The speaker circuit is fairly simple. Not too many components to check. I would suggest checking the resistor next to the speaker connector. Just seems like the place that would be letting current through to make a steady noise.

You can have 4 floppy drives. Getting all 4 internal would require half height drives, the special adapter to mount half height drives, and some cable to attach two drives to the external floppy connector. Any mix of single sided and double sided and even (with a little effort) 80 track drives can be done though why bother with single sided drives since double sided drives can be told to ignore the unneeded side.
 
krebizfan said:
The speaker circuit is fairly simple. Not too many components to check. I would suggest checking the resistor next to the speaker connector. Just seems like the place that would be letting current through to make a steady noise.

You can have 4 floppy drives. Getting all 4 internal would require half height drives, the special adapter to mount half height drives, and some cable to attach two drives to the external floppy connector. Any mix of single sided and double sided and even (with a little effort) 80 track drives can be done though why bother with single sided drives since double sided drives can be told to ignore the unneeded side.
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Why single sided? I have 6 early IBM's. This will be the only 1981 16KB board I have. I dont need it to have all the bells and whistles. My 5160 with 386 card pretty much has that covered. I just want to have an early variant in the collection. Why a 160KB drive? Why not.. its an oddity. I dont even mind the 500+ memory limitation, I was just hoping for XTIDE so I can get files to and from it easily.. that would have been my only real upgrade.. but that seems like its a big problem.

I will check out the circuit near the speaker output.
Timo W. said:
I see. But I would guess many, or even most owners back then later swapped in the 1982 BIOS anyway. It would still be period correct.

Or maybe you can swap the BASIC ROM with the XT-IDE ROM?
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Seems the 1982 bios is my only real option.
 
Bear in mind that when the 5150 was first released, it could be had with a tape drive and DOS 1 didn’t even support hard disk drives.

Whilst there is a novelty of booting one from tape, tbh these really early configurations aren’t that interesting as their functionality is really limited.

However, with DOS 3 and a fixed disk and a sound card, things get much more interesting, for me anyway. Showing one running 8088 Corruption for example is quite something.
 
"Tape drive" is a very generous term for the cassette recorder :LOL:

A "period correct" 5150 would need to have MDA/CGA/Hercules as well.
 
There were hard drive options that required booting from floppy first, but they seem uncommon. I wonder if there are any floppy-boot drivers for more common WD, DTC, and Seagate controller?
 
You can load XTIDE Universal BIOS from floppy actually, or even tape I suppose - but would need to use DOS 2
 
Plasma said:
"Tape drive" is a very generous term for the cassette recorder :LOL:

A "period correct" 5150 would need to have MDA/CGA/Hercules as well.
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The cassette recorder was good enough for CP/M to use as a backup system with the Tarbell interface. I had thought about taking the CP/M cassette software, replacing the Tarbell cassette code with INT 15h calls, and porting it over to PC-DOS. Alas, I lack the skills to pull that off quickly. A single use joke software needs to be doable in 15 minutes or so but the project would have taken a lot longer.

I would have to double check the timeline but a 5150 with single sided drives would have MDA and only MDA. CGA was delayed slightly and I think IBM was offering double sided drives by the time CGA shipped. Hercules shipped about a year after the 5150 so not period correct for a system with single sided drives besides the fact the IBM didn't off it.
 
Would be a good move updating that BIOS. I purchased one new in 01/82 and, like most users then, RAN to Computerland when the new BIOS was announced, adding an ST225 right after.
Still have it today and feel it’s period correct running an original AdLib, noisy HD and Xtide.
 
Again I have a 5160 (which I have had since the 80's as it was my first computer... with all the bells and whistles..) I am not looking for all the bells and whistles.. just useability.. And it seems that wasnt a feature on the first run of the 5150.

The machine is still going to have a 160KB floppy drive and a hercules card and a 5151 monitor.
 
I was considering period correct to be anything before the 5160 release. If you are trying to do an "as purchased" config for an early 64K system, that's going to be a lot more limited.
 
krebizfan said:
I would have to double check the timeline but a 5150 with single sided drives would have MDA and only MDA
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I was actually under the impression that it was MDA that was delayed; this makes more intuitive sense to me given one of the original SKUs of the PC was the diskless version intended to be hooked up to a cassette recorder and a home TV set via RF modulator.

EDIT: what you may be remembering is the matching 5153 CGA *monitor* didn’t come out until 1983; early buyers of the PC were on their own finding a monitor, which is why both composite-optimized CGA games and the option in some older software to not rely on the “intensity” line being wired up (8-color digital RGB monitors were perhaps the most common variant in the wild in 1981) were both “things”.
 
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I have plenty of 8 bit video cards. I wanted to use a Real Hercules card on this machine although I think I do have the IBM MDA card as well.
 
When DOS 2.0 came out with the ability to load device drivers, my 5150 got a hard drive--a SA1002 8" drive connected to a WD1001 controller, hitched to a small ISA card I made (still have it) in the 5150. Boot from floppy, load the driver and you're good to go with a glorious 4MB of disk. My 5150 was modified with the Purple Computing mezzanine board to a whopping 256KB. (still have the docs for that one).
 
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