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Breathing new life into 1981 IBM 5150

mR_Slug said:
There were some hdd solutions for dos 1 on the early bioses but I think they either required a boot disk with a modded dos, or some emulated a floppy. Read about one system that split the hdd into multiple floppys and had tools to switch to them.

There were also lots of 'floppy emulators' As far as i can tell these are hardware ram drives. Would like to get my hands on one of these as well as one of the early hdd systems.

There were also ads for upgrade quad density drives, not sure how dos got on with them.

It's your system so it's up to you how you proceed but if it were mine (and I had the other later 5150s), I would try to trick it out with an external HDD within the confines of the first rev BIOS. Ideally with an original solution, but i guess you could always brew your own.

Emulating the floppy seems to be the place to start. I think smbaker or smbarker made a card that could emulate a floppy controller. His you could load disk images via a network. So that should work, but it could be made much simpler by responding to the correct I/O address and store a 160K floppy in an EPROM. Would this work? Is this a relatively simple card to make.
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Im not opposed to loading off a floppy to gain suplkrt for hard drives. i have real floppy hardware so i would much rather use an actual floppy drive.
 
So I finished work on the original 1981 Black PSU. When I got it, it was shot. It kept blowing fuses and shorting out. I worked on it for 3 days but decided why am I trying so hard on an under powered PSU?. Shelbey from Techtangents had a video a couple years back about a new AT PSU and he did a review on it. I cannot find that video I think he took it down, but regardless I bought that unit and intended on doing a swapout of the internals of this original Black PSU. It has been on the back burner for quite some time but I worked on it yesterday and finished this morning.

I took apart the new AT unit to see if it would be relatively easy, it was:IMG_20220717_153345.jpg

I removed all the old boards and cabling and cleaned the chassis. There was some minor corrosion so I painted the removeable plate which holds the Big Red Power rocker switch and test fitted the new psu board inside:
Resized_20220717_161902.jpeg The 115V to 220V selector is what you see heatshrinked at the top.

Next was the Fan. Id like to keep the AC fan as the sound is something I remember so much from back then but its a Big heavy AC fan and I didnt feel like integrating it. An 80mm DC fan is quiet and light. So that what I went with.
Resized_20220717_163626.jpeg You can see the heavy AC fan off to the right. ITs still an 80mm fan so it works out fine.

Here is the completed PSU all buttoned up and honestly if I didnt remark on it most people would probably not notice. I know its going to be much more reliable now.
Resized_20220718_104637.jpegResized_20220718_104716.jpeg

I did something very similar with my 5155 about 8 years ago. The 5155 has a HORRIBLE PSU. It was a nightmare that me and the guys at work could not get working again. SO I gutted it with another psu and its been fine since.

By the way, if anyone wants the guts of the original 1981 black PSU for repair or parts I will only charge shipping. If I dont hear something within a week into the junk they go, no tears will be shed. I wont be including the AC fan due to the weight. And I removed one AT power connector since I needed one. Other than that its complete. Here is a photo of those parts:
IMG_20220718_111950.jpg
 
So since the BIOS on this original board are so limited I want to try a new Bios. I will not be getting rid of the originals as I feel they are part of this machine. I just want to try doing something with the machine.

This had multiple rom sockets so how many Roms Do I need to burn? What type of eproms do I need and where can I find the newest/best rom for a 5150? I have never replaced roms on a PC compatible before (other than swapping out chips for an AMI bios that is).
 
Chuck(G) said:
If you don't care about BASIC-in-ROM, you only need a single BIOS ROM.
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Just 1 eprom? the rest are BASIC? If thats the case, sure. I never really used BASIC on a 5160 or 5150 anyway. One question. Since a few new games/programs have been made to take advantage of the cassette port on the 5150.. I take it I would use Cassette functionality.
 
I’ve used the Motorola MCM68766 and Texas Instruments TMS2564 successfully in a 256K 5150.

65695840-F7FA-446E-A886-9982B3EB5AC8.jpeg

I’ve heard of people using the waferscale ws57c49c in a Commodore 64, so I’m guessing it would work too.
 
VERAULT said:
Just 1 eprom? the rest are BASIC? If thats the case, sure. I never really used BASIC on a 5160 or 5150 anyway. One question. Since a few new games/programs have been made to take advantage of the cassette port on the 5150.. I take it I would use Cassette functionality.
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Depends on how said games use the cassette facility. The BIOS support is still there, even if ROM-basic isn't.
 
I honestly don't know, do you actually have to swap the BASIC ROMs if you upgrade the core BIOS from the original to the extension-supporting version?
 
Ok so this is a bit confusing. According to this site: http://minuszerodegrees.net/5150/motherboard/5150_u33.htm I need a 64kbit eprom and 27XX series wont work without an adapter. I have plenty of 27 series eproms and I just found a 23XX adapter I bought from go4retro years ago on my pinup board : https://store.go4retro.com/2364-adapter/

Now to find the right eprom.


I guess my last question is which rom. I can use the last bios release on the 5150 10/27/82 which has support for EGA etc video cards. But is there something newer made by the community with even more options or gets over memory limitations. If I am replacing the rom (not permanently of course as I mentioned I want to keep this as an early example) to use more functionality might as well go big.
 
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VERAULT said:
Ok so this is a bit confusing. According to this site: http://minuszerodegrees.net/5150/motherboard/5150_u33.htm I need a 64kbit eprom and 27XX series wont work without an adapter. I have plenty of 27 series eproms and I just found a 23XX adapter I bought from go4retro years ago on my pinup board : https://store.go4retro.com/2364-adapter/

Now to find the right eprom.


I guess my last question is which rom. I can use the last bios release on the 5150 10/27/82 which has support for EGA etc video cards. But is there something newer made by the community with even more options or gets over memory limitations. If I am replacing the rom (not permanently of course as I mentioned I want to keep this as an early example) to use more functionality might as well go big.
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I believe Mr. Kiselev wrote an XT BIOS ROM you could try
 
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