Subj : IBM PS/2 Model 25 questions
To   : Christopher Simms
From : andrew clarke
Date : Fri Feb 12 2016 20:03:58

11 Feb 16 22:57, you wrote to all:

 CS> Hi folks, I have a few questions regarding a 1987 IBM PS/2 Model 25
 CS> I've been tinkering with:

 CS> 1) Is the Model 25 capable of color? If so, how do I enable it in DOS
 CS> 5.0?

There are several different Model 25s but only some are colour. It's possible 
yours is VGA but only has a greyscale monitor.

An quick way to test whether you've got VGA with MS-DOS 5.0 would be to run 
this in QBASIC:

SCREEN 12
CIRCLE (200, 200), 50, 4
CIRCLE (200, 200), 100, 2
CIRCLE (200, 200), 150, 1

This switches to 640x480 graphics mode (16 colors) and displays red, green and 
blue circles on the screen.

If you get an error or a blank screen you probably have a monochrome graphics 
card.

If you get grey circles on the screen, you have a greyscale monitor.

 CS> 2) What telnet clients are available for DOS 5.0?

mTCP Telnet should work. You'll just need to find the correct driver for the 
PS/2's network card, though.

http://www.brutman.com/mTCP/mTCP_Telnet.html

 CS> 3) Would it be possible to install and run Linux via dual-boot on one
 CS> of these computers?

Linux requires at least a 80386 CPU, however most PS/2 Model 25s have either 
8086 or 80286 CPUs.

Even if your PS/2 is a 386SX model, you're unlikely to have enough RAM onboard 
to boot the Linux kernel, nor sufficient disk space to install the base OS.

Something like Xenix might boot on your PS/2, but it'll be painful to use. For 
that machine I'd stick with mTCP on top of MS-DOS.

 CS> I've been getting into vintage computing as a hobby lately, but there
 CS> are some things I need help with from time to time. Thanks all and I
 CS> look forward to hearing from you!

I wish I'd kept some of my older PCs, but they can be a real pain to keep 
going.

Currently my oldest PC is from 1995, unusually with a Cyrix 6x86 CPU. To my 
surprise the onboard battery is still working, keeping the clock ticking over 
and BIOS settings intact.

I also have a working Pentium 90 motherboard, but no case to put it into yet.

Have you looked at emulators? Running DOSBox, VirtualBox or PCem-X on a modern 
PC can be useful. Obviously it's not the same experience as using the real 
thing, but it can be very handy for experimenting with software before running 
it on real hardware.

There's also the http://www.pcjs.org/ web site, where you can emulate early PCs 
entirely in a modern PC's web browser (using JavaScript).

Regards
Andrew

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