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IBM 5150/5160 Questions

Lutiana

Lutiana

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Okay, I have a few:

1. Will the IBM 5150 and 5160 work with the 28C256 chips? If not, what type of EEPROMS are best?
Answer:

  • The 5160 can use the 27C256 chips, which are *almost* identical to the 28C256 chips. Pin 1 on the chip needs to go to pin 27 on the socket and pin 27 on the chip can be bridged to pin 28 (to disable write enabling).
  • The 5150 can use the 28C256, but there will be 4 pins not in the socket (1,2, 27 and 28 ), you then need to lift pin 26 and run pin 27 on the chip to pin 24 on the socket and bridge pin 27 on the chip to pin 27 on the chip (that runs to pin 24 on the socket). You then need to tie pins 1,2,26 and 28 to pin 27 (to tie them high).

2. I have a 5150 motherboard that has some minor corrosion around the crystal. So I am wanting to replace it. What specs should I be looking for? Answer: 14.31818 MHz

3. Where can I get a replacement connector for AT power input on a motherboard? What is that connector called? Answer: It is a Molex 15-48-0106, which is obsolete but you can get a Molex 36642-0001, which is the replacement.

4. What is the best way to clean minor corrosion from a 5150 motherboard? I don't think any traces are damaged, it seems like it is surface corrosion only.

5. Someone mentioned you can hack a 5160 motherboard so that it will have 640kb of memory on board, can the same be done for a 5150? I cannot find the link that someone posted about this, so if you have it can you post it? Answer: It is theoretically possible, but not easy at all.
 
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lutiana said:
Okay, I have a few:

1. Will the IBM 5150 and 5160 work with the 28C256 chips? If not, what type of EEPROMS are best?
Click to expand...
I use 29C256 EEPROMs on my 5155(same motherboard as early 5160). I went that route because they are closer to being pin compatible to the original EPROM. Only one mod necessary to prevent incidental writing to the chip


lutiana said:
5. Someone mentioned you can hack a 5160 motherboard so that it will have 640kb of memory on board, can the same be done for a 5150? I cannot find the link that someone posted about this, so if you have it can you post it?
Click to expand...
With just a little more effort you can put 1 MB on the 5160 and have UMB memory for mouse drivers and network drivers and such. I'm not sure about the 5150. I could have sworn I saw a mod mentioned somewhere to put 640k on the 5150 motherboard but I can't find it now.
 
Here is a document describing it for the 5160: http://www.minuszerodegrees.net/5160/motherboard/5160_upgrading_256k_motherboard_to_640k.pdf
It describes modifying a 'type 1' (64k-256k) XT motherboard to a 'type 2' motherboard (640k).
I suppose in theory you could make it work for the 5150 as well, but the question would be: how much modification would have to be done?
I believe there are also two types of 5150 motherboard: 16-64k and 64k-256k, see here:
http://www.minuszerodegrees.net/5150/motherboard/5150_motherboard_revisions.htm
The latter should not be too different from a 'type 1' XT motherboard, so by that logic, it should be doable to perform the 640k mod on it as well.
It uses 4 banks of 4164 memory chips, just like a 'type 1' XT does.

The older motherboard uses 4 banks of 4116 memory. It will be harder to modify that one, but perhaps not impossible either.

The circuit diagrams for all boards are available in the respective manuals, so someone with enough knowledge of these early memory chips should be able to figure out what the relevant changes were between the different models, and figure out how to do it.

Apparently someone did it to fatwizard's 5150 256k board in the post that Stone linked above. I can only say... it doesn't look easy :)
 
ibmapc said:
I use 29C256 EEPROMs on my 5155(same motherboard as early 5160). I went that route because they are closer to being pin compatible to the original EPROM. Only one mod necessary to prevent incidental writing to the chip
Click to expand...

The 28C256 work well on the 5170 motherboard, and they are what I have. So i am really hoping that they would work in the 5150 and 5160.


ibmapc said:
With just a little more effort you can put 1 MB on the 5160 and have UMB memory for mouse drivers and network drivers and such. I'm not sure about the 5150. I could have sworn I saw a mod mentioned somewhere to put 640k on the 5150 motherboard but I can't find it now.
Click to expand...

The 512-640 upgrade for the 5160 is VERY easy from what I read. So how do you do 640-1024? I read the post that Stone posted and it seemed like there was quite a bit of fiddling with code and PROMS to do this. Is there a step by step guides somewhere?
 
I've not seen that before, It looks like a lot of work, I have a sixpakplus card in my 5150 which takes it to 640k, It also benefits from having a clock / serial and parallel port.
 
ibmapc said:
That shows both topics (5150 640k mod and 1 MEG XT mod) on one page. Great find Stone. A direct link to the tread about the 1 MEG XT Mod is HERE.

PS
I am still willing to supply the GAL to do the 1 MEG XT mod for the cost of shipping.
Click to expand...

So the mod is simply replacing the BIOS with the GAL and putting in 256k chips in all the banks? I tried to follow the thread, but got lost (probably doesn't help that I have about 10 things going in at once here).
 
lutiana said:
So the mod is simply replacing the BIOS with the GAL and putting in 256k chips in all the banks? I tried to follow the thread, but got lost (probably doesn't help that I have about 10 things going in at once here).
Click to expand...

Yes, that is a long thread. It's the PAL at u44 that gets replaced by the GAL(not BIOS) and then it's just a matter of putting USE!UMBS.SYS on your hard disk and modifying config.sys and autoexec.bat. I'll type up some instructions to make it easier to follow but it's really not very difficult.
 
One of the biggest changes from the 5150 to the 5160 motherboard is that the 5160 has a way more flexible memory layout. While the 5150 is hardwiered for one spesific type of RAM, the 5160 allows for a wide variety of different RAM-type combinations. By default it has presets for 4 different scenarios:

* all 4164 (default, 64K steps up to 256K)
* a combination of 4164 and 41256 (later default, needs a multiplexer in the empty socket, 640K max)
* all 4216 (64K only, needs some additional jumper modifications)
* all 41128 "piggybacked" dram (needs multiplexer, 128K steps up to 512K)

Everything is controller by a small ROM chip decoder that mannages the select lines to the different banks. The 1MEG mod replaces this ROM with one that also enables RAM in upper memory.
 
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ibmapc said:
Yes, that is a long thread. It's the PAL at u44 that gets replaced by the GAL(not BIOS) and then it's just a matter of putting USE!UMBS.SYS on your hard disk and modifying config.sys and autoexec.bat. I'll type up some instructions to make it easier to follow but it's really not very difficult.
Click to expand...

I'd like to get one or two of the GALs from you then for my 5160s and give it a go. I know that one of them has a 256-640 motherboard, but I am not sure about the other one (though I am thinking it is the first revision mb). Having 1Mb on each of them would be quite useful.
 
per said:
One of the biggest changes from the 5150 to the 5160 motherboard is that the 5160 has a way more flexible memory layout. While the 5150 is hardwired for one specific type of RAM, the 5160 allows for a wide variety of different RAM-type combinations.
Click to expand...

Yes, I am realizing that upgrading the memory past 256Kb on the 5150s I have is not really going to be all that feasible. So I'll just look to add in ISA cards to fill out the memory on them.
 
lutiana said:
...I know that one of them has a 256-640 motherboard, but I am not sure about the other one (though I am thinking it is the first revision mb). Having 1Mb on each of them would be quite useful.
Click to expand...
The 256-640k motherboard may be a little more difficult. The ones that I've seen have the PROM at u44 soldered directly where as the 64-256k boards use a socket for u44. You would have to de-solder the chip on the 256-640k board (and solder a socket of coarse). None the less, I'd be happy to supply the GAL(s) and some basic instructions. I could even put the latest version of USE!UMBS.SYS on a 360k floppy if you like. Just send me a PM with your address, and I'll get it going.
 
ibmapc said:
The 256-640k motherboard may be a little more difficult. The ones that I've seen have the PROM at u44 soldered directly where as the 64-256k boards use a socket for u44. You would have to de-solder the chip on the 256-640k board (and solder a socket of coarse). None the less, I'd be happy to supply the GAL(s) and some basic instructions. I could even put the latest version of USE!UMBS.SYS on a 360k floppy if you like. Just send me a PM with your address, and I'll get it going.
Click to expand...

That would be awesome. I'll have to take a look at the 5160 I have at home later tonight and see if U44 is soldered on or not. I don't really have an issue unsoldering and replacing it with a socket if i have to.
 
So I still need the answers to these:

2. I have a 5150 motherboard that has some minor corrosion around the crystal. So I am wanting to replace it. What specs should I be looking for?

3. Where can I get a replacement connector for AT power input on a motherboard? What is that connector called?

4. What is the best way to clean minor corrosion from a 5150 motherboard? I don't think any traces are damaged, it seems like it is surface corrosion only.

And maybe an idea of what chip type to use for an IBM 5150s bios.
 
2. Look for 14.31818 MHz. It can be trimmed a bit with the variable capacitor, but CGA composite will only display proper colors if it's tuned spot on.

For the BIOS, the chip you want to look for is the 2364.
 
per said:
2. Look for 14.31818 MHz. It can be trimmed a bit with the variable capacitor, but CGA composite will only display proper colors if it's tuned spot on.
Click to expand...

There is a an adjustable thingy on the motherboard, which I assumed was for just this purpose based on reading things about the 5150. Would the variable capacitor be in addition to this?
 
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