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IBM PS/2 Model 25

RWallmow

RWallmow

Veteran Member
Joined
Oct 19, 2006
Messages
1,791
Location
Anoka, MN USA
DSCN0440.JPG
System Specs:
Intel 8086 CPU running at 8mhz
512 or 640k RAM
Single or Dual 720k 3.5" Floppy drives
Optional 20mb Hard disk (supposedly ST506 signaling on proprietary connector on planar)
MCGA Graphics with 12" CRT
2 ISA Slots (8-bit)

The hard disks that were used in these commonly fail and most users would install some kind of Hard Card, SCSI card, or IDE card for connecting more common hard drives.

Another useful upgrade is to replace the Intel 8086 with an NEC V30, this should allow the computer to run Windows 3.0 with the VGA driver, as well as SOME other applications that would normally require an 80286, as the V30 has SOME (but not all) of the 286 instructions. It will also boost 8086 native code execution speed approximately 5% due to being able to execute some operations in one clock cycle that would take a native 8086 multiple clock cycles to complete. Contrary to what the Windows 3.0 setup says, the MCGA driver works fine on the 8086 CPU.
 
I have a correction for this article. The v30 will allow windows 3.0 to load a VGA driver, the mcga driver works on the 8086 too.
 
evildragon said:
I have a correction for this article. The v30 will allow windows 3.0 to load a VGA driver, the mcga driver works on the 8086 too.
Click to expand...
The install of Windows 3.0 I did on mine, the MCGA driver said (286 only) or something similar right after it, so I assumed it wouldn't load on a stock 8086.
 
I'm fairly certain it's referring to the vga driver.

I may be wrong though, but I faintly remember it was that if you were on a stock 8086 driver, you would get 1-bit monochrome mcga.
 
evildragon said:
I'm fairly certain it's referring to the vga driver.

I may be wrong though, but I faintly remember it was that if you were on a stock 8086 driver, you would get 1-bit monochrome mcga.
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I have no take on if it REALLY works this way, but I just confirmed it CLAIMS to require a 286 for MCGA, here is the screen shot on the PS/2-25
DSCN0458.jpg
 
Hmm, I wonder now.. Maybe I am wrong. Seems odd though, cause windows 2 works in VGA on the 8086. I remember I bought the v30 for something, maybe it was this.
 
evildragon said:
Hmm, I wonder now.. Maybe I am wrong. Seems odd though, cause windows 2 works in VGA on the 8086. I remember I bought the v30 for something, maybe it was this.
Click to expand...
I have no doubt VGA mode in 3.0 probably requires it as well, I didn't check since its not relevant to my Model 25, but it clearly states it needs 286 on the setup, I didn't try it on the 8086, but the MCGA driver DOES work on the V30, I have still not been successful loading 3.0 on it yet, but it does get as far as the GUI portion and the driver loads, my install is failing about 40% on copying files, its hard-locking. I think its the hard drive, but time will tell when I try a different drive.
 
Yea, I use Windows 3.0 on mine, with a V30, running the MCGA driver (also works with a VGA card too on the VGA driver). I have many videos showing it off. So it does work, that's for sure.

I can't test the 8086 though, as my hard drive requires a 286 :p
 
Got Windows 3.0 working finally, I ended up finding the NYB virus on the old HardCard 20 I have in my Model 25, I wiped the drive clean, fdisked and reformatted and I was finally able to get windows installed and running. Sadly now I have run into problems with MSNET software, it requires a 286, and the V30 isn't providing enough of the instruction set to satisfy it, so it looks like I will never be mapping to network drives on this one. Question now is, do I keep the NIC in it and use mTCP for FTP file transfers forgoing direct drive letter mapping, OR pull the NIC and install the TMC-850IBM SCSI card I have and work on getting a Jaz/Zip drive and maybe even a CD-ROM going on it (The SCSI option I may be able to pull the HardCard and pickup a SCSI hard drive to rig up internally somehow, and keep both NIC and SCSI).
 
You are missing a few things
1) shipped with IBM-branded Windows 1.04 "Collegiate Kit" software option
2) 80C86 processor not 8086 - right?
3) did not have actual ST506 hard drives, too physically large!
4) choice of color or greyscale video

lastly, why does a wiki have opinions in it? More facts, less off the top of the head stuff, k?
 
billdeg said:
You are missing a few things
1) shipped with IBM-branded Windows 1.04 "Collegiate Kit" software option
2) 80C86 processor not 8086 - right?
3) did not have actual ST506 hard drives, too physically large!
4) choice of color or greyscale video

lastly, why does a wiki have opinions in it? More facts, less off the top of the head stuff, k?
Click to expand...
1. May have, not sure.
2. No, mine was an 8086, Maybe later ones switched?
3. ST506 signaling on proprietary cable interface for proprietary drive (and this is just gleaned from other sources, could be something completely different, one site lists as ST506 compatible interface, not confirmed, maybe youre right and this should be left out since its not for sure)
4. You could be right, color may have been an option in the 8086 config, the "Model 25-286" were common in color, and the 8086 were typically grayscale, but could have been available in color as well, this article should probably be renamed PS/2 "Model 25-XT" or "Model 25-8086" as other than case design they are very different from their Model 25-286 namesakes)
 
I worked at IBM in 1987 when the PS/2 line was launched. The PS/2 25 was officially the model 8525. All Wiki entries on this system should have only proper model numbers. I don't suggest you make up new model names as this is supposed to be an authoratative source of factual information.

I believe you should get all of the details from an official source, not me, and not copy and paste from the other Wikis on the web. For example the processor I am *pretty sure* is 80C86. I will have to crack one open to verify if you have no other source for this info. The Wiki's have no/few references to the fact that this was the computer that came with IBM branded Windows 1.0. I think the 8525 was the first IBM computer sold with IBM branded Windows.

WHen I got my model 25 in 1987 (employee discount) I had the choice between MCGA greyscale or color.
 
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billdeg said:
I worked at IBM in 1987 when the PS/2 line was launched. The PS/2 25 was officially the model 8525. All Wiki entries on this system should have only proper model numbers. I don't suggest you make up new model names as this is supposed to be an authoratative source of factual information
Click to expand...
Change it then, its a wiki, thats the nice thing about them the community can change them...

billdeg said:
I believe you should get all of the details from an official source, not me, and not copy and paste from the other Wikis on the web. For example the processor I am *pretty sure* is 80C86. I will have to crack one open to verify if you have no other source for this info. The Wiki's have no/few references to the fact that this was the computer that came with IBM branded Windows 1.0. I think the 8525 was the first IBM computer sold with IBM branded Windows.
Click to expand...
There is no available official source, goes back to my first comment, if you think its wrong, its a wiki, change it...
Also the Model 25's were all called model 8525 regardless of 8086, 286, color, etc, so going by the proper model number doesn't help differentiate between the different ones either, most sites out there refer to them as the Model 25-XT and Model 25-286 since they were both called model 8525.
billdeg said:
WHen I got my model 25 in 1987 (employee discount) I had the choice between MCGA greyscale or color. MCGA is not "CGA" it's
Click to expand...
Not sure where you were going with that, but I never said it was CGA, the wiki says MCGA.


EDIT: My opinion anyways is, as long as the info isn't blatantly wrong, I think a minimal and speculating (as long as its stated its speculated, like I did saying the HD interface is "SUPPOSEDLY ST506 SIGNALING") wiki article is better than NO wiki article.
 
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RWallmow said:
Change it then, its a wiki, thats the nice thing about them the community can change them...


There is no available official source, goes back to my first comment, if you think its wrong, its a wiki, change it...
Also the Model 25's were all called model 8525 regardless of 8086, 286, color, etc, so going by the proper model number doesn't help differentiate between the different ones either, most sites out there refer to them as the Model 25-XT and Model 25-286 since they were both called model 8525.

Not sure where you were going with that, but I never said it was CGA, the wiki says MCGA.


EDIT: My opinion anyways is, as long as the info isn't blatantly wrong, I think a minimal and speculating (as long as its stated its speculated, like I did saying the HD interface is "SUPPOSEDLY ST506 SIGNALING") wiki article is better than NO wiki article.
Click to expand...

OK...I will put my money where my mouth is and try to help provide what details I have. I still have most of the orig. docs, etc.
BIll
 
For anyone interested, I checked and the original CPU from MY particular PS/2-25 was an 8086, not 80c86, not trying to say either myself or billdeg is right or wrong, IBM could have used both in the several year run of the Model 25, or mine could have been swapped by a previous owner, who knows.

Photo of my CPU:
i8086.JPG
 
I have both the late model 25's (early 90's) and early model 25 motherboards, neither use 80c86, always used a full size 8086..

The 8086 models DID come in both greyscale and color. I used to have the color model before the PSU fried. It was only worth it in 320x200 though as 640x480 usually was black and white (unless a program changed the 1-bit palette).
 
RWallmow said:
For anyone interested, I checked and the original CPU from MY particular PS/2-25 was an 8086, not 80c86, not trying to say either myself or billdeg is right or wrong, IBM could have used both in the several year run of the Model 25, or mine could have been swapped by a previous owner, who knows.
Click to expand...

I was wrong there is no 80c86.

I took a few apart. There seems to have been two major revs of this system. Both 8086s
 
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