Tuesday, August 22, 2006
IBM PS/2 Model 25 used as a serial console
Model: PS/2 8525
(a.k.a. PS/2 Model 25)
CPU: 8086, 8MHz
RAM: 256kB Base, 768K loaded
Release Date: Aug 11, 1987
The Personal System/2 was one of IBM's longest lasting desktop product lines. Although USB has recently become the more popular human input device (keyboard/mouse) interface, the IBM PS/2 computer is the namesake of the older PS/2 keyboard and mouse ports found on most IBM PC Compatables in the 90's and through today. The 8525 was one of the first machines to use 72-pin SIMM memory modules instead of the older 30-pin SIMMs. the 72-pin layout would also set a long-running standard in the computer industry, lasting well into the late 1990s on many computers even beyond the PC/XT compatible realm (Macs, Sun, RS/6000 and others)
The PS/2 8525 borrowed the "all in one" design from Apple Computer, placing the monitor, motherboard, internal peripherals and drives into one case. The end result was a machine that's about as bulky as my Performa 550 but the same age as the Macintosh SE. The screen is much larger, and the later revisions of the 8525 offered a 16 color MCGA display. The first batch shipped with monochrome monitors.
Inside, the MicroChannel Architecture motherboard and riser card provided 2 MCA expansion slots. The most common drive configuration was two 720k 3.5" floppy drives, however a spendy option package replaced one of them with a miniscule (by today's standards) internal hard drive.
Ultimately, the 8525 found its role in education, much like Apple computers of similar vintage. A few companies dared to offer upgrades targeted just for this family of machines. IBM itself eventually released a 286-powered version, and from there, companies begun selling 386 and 486 upgrades, some of which involed completely swapping motherboards. As this system had built-in video and a small internal form factor, there was no hope for simply buying another generic motherboard. As a matter of fact, the "generic motherboard" and "build your own PC" concepts wouldn't show up until several years after the 8525 was announced.
My last weekend edition post talked about thin clients, and even mentioned "green screen" terminals of days gone by. This system has pretty much been a "thin client" of sorts ever since I purchased it in 1995. For the longest time, it was used only as a BBS terminal. Paired with MS-DOS and TeleMate, a modem/terminal emulator program, my girlfriend (now wife) and I would use it to connect to BBSs, MUDs, UNIX servers and other dial-up resources.
Later on, I used telemate in a less traditional role to turn the 8525 into a text terminal for my Linux box, in essence, it was a very primitive thin client, used for reading my e-mail, writing for my old e-zine, and doing remote system administration work.