The Independent Kixmiller Pigeon MrkII

May 26, 2021

Big Blue's attempt at recapturing the PC market

The IBM PS/2 Family of Computers. Image From Wikipedia.

This is a continuation of the articles covering the history of PC's using emulators to illustrate the march of progress. This is part 2 in the series of articles covering the IBM PS/2 family of computers.

IBM PS/2 Model 50

I would rather use a screwdriver and swap out universal components instead of dealing with proprietary, odd-ball crap. This was something I expected from Apple, but not IBM!

Introduced in 1988, the Model 50 was a 286 workstation that actually was a true PS/2 in that it contained the MCA bus architecture. The Micro-Channel bus architecture allowed peripheral devices to run at much faster speeds compared to the ISA slots found in most desktop computers. As mentioned in the previous article, the peripheral devices could be configured via the starter disk with the drivers. No need to use jumpers.

One thing to note was that the Model 50 incorporated a cable-less design. This meant that the computer could be disassembled without the needs for tools. I actually played around with this computer before as a pet project. On one hand, it was amazing that I didn't need a screwdriver to disassemble the PC. At the same time, this design also made all the components in the machine very proprietary to that particular system. My machine, a Model 50z, didn't have neither a working floppy or hard-disk. I couldn't swap out neither component as the drives were specific to that cable-less design. There was nothing I had in reach that was compatible with that PC. I ended up hating the design, despite it's ease of use. I would rather use a screwdriver and swap out universal components instead of dealing with proprietary, odd-ball crap. This was something I expected from Apple, but not IBM!

This computer is emulated within the PCEM emulator, so I get to try out those pet projects virtually now. The Starter Disk for that particular system was needed to configure the memory, hard-disk controller, BIOS and other peripheral devices in the system. Like in the previous article, one of the ADF files on the disk image needs to be replaced in order for the hard-disk to be recognized.

After the restart, I was able to install both DOS and OS/2. By the time the Model 50 shipped, IBM PC-DOS 4.0 was out, along with OS/2 Version 1.1. This particular version of OS/2 had the completed graphical environment, called the Presentation Manager. One thing to note is that OS/2 with the PM was a very demanding system. Using the early OS/2 versions made me realize why this OS never caught on: it required very expensive hardware to run it. As a result, most opted to run DOS, and fewer people running OS/2 meant even fewer software developers to write applications for the OS. OS/2 with the PM was unusable. But it felt sluggish most of the time.

DOS 4.0 shipped with the DOS Shell. The DOS Shell was a environment that intended on making the OS easier to use. It was very reminiscent of early Windows and served as a application launcher.

My emulated Model 50 had 4 MB's of RAM. Now, I was using a older build of PCEM (13) which allowed me to set the speed of the 286 processor. The speed was set to 25MHz, which was the fastest speed supported by the processor. Even then, OS/2 felt sluggish. Now in some ways, I'm glad my real system didn't work. It would have made that project a exercise in frustration. Despite that though, I;m glad that I finally did get the opportunity to try out the system. This also highlights that emulation will become the only path when real hardware dies.

The DOS Shell Program that Shipped With DOS 4.0.

OS/2 Version 1.1 running on the Emulated Model 50.

Database design on OS/2 via the Query Manager. Database design with the Query Manager is representative of the software that users would have interacted with on these systems. Later version of this program were GUI-based.

OS/2

OS/2 shipped a couple of months after the Model 30 did. OS/2 had been intended on having a graphical interface from the start, but due to time constraints of shipping the software on time, the first version of OS/2 was restricted to text-mode as a character-based OS, like DOS. Don't be fooled though, as even back then, OS/2 could run applications that could use more than 640KB of RAM, along with multitasking support, memory management and protection. One thing to note was that all versions of OS/2 v1.x were designed to run on the 286. As a result, since the 286 processor didn't support a virtual 8086 mode like the later 386 processor did, OS/2 only supported one DOS session for backward compatibility. Also, due to this compatibility, it was still possible for a badly-misbehaving DOS program to crash the entire computer.

OS/2 was jointly developed between IBM and Microsoft as the intended successor of DOS. Applications written for OS/2 could use more than 640KB of RAM, which was something that DOS programs couldn't do (yet, as DOS extenders was barely a thing at this time). Also, OS/2 would have preemptive multitasking and multi-threading operations. Multi-threading is where a program can perform multiple task. For example, a spreadsheet program would let it's user continue working on the document while it was printing at the same time. A web-browser would let its user work surf the web while a file downloads in the background. Applications that didn't support multi-threading operations couldn't allow this.

Even though environments like DR-GEM and Windows allowed multiple programs to be opened, only the active program was running, with the programs in the background frozen until the user selected them. This was referred to as cooperative multitasking. The Mac System software before OS X had this form of limited multitasking as well.

Model 55

The Model 55 was IBM's awnser to the Compaq Deskpro 386. Compaq's introduction of the Desktop in 86/87 sent shock-waves throughout the computing world as the Houston Company released a 386-based computer before Big Blue did. Essentially, IBM was playing catch-up. Despite that though, the MCA architecture plays very well to the 386's strengths, mainly in performance. The MCA slots could operate at much faster speeds than the ISA slots used in the AT clones. As a result, the MCA slot could make better use of the faster performance of the 386 than ISA could.

DOS and OS/2 shipped on these computers as well. On the PCEM emulator. I've installed both OS/2 Version 1.2, which shipped in 1989, along with IBM PC-DOS Version 4.0. Despite being designed for the 286, OS/2 was much more responsive on the 386. I've gave my OS/2 setup 4MB's of RAM to play with, along with a 60MB Hard-Disk. A computer like this would have commanded a astronomical price tag, costing around $5,000-$7,000 back in the day.

Yep, I've seen this before. Error Message. It can often be resolved with a proper reconfiguration of the BIOS via the Starter Disk.

OS/2 Version 1.2