Classic Computers Emulated: The IBM Personal System/2 Family of Computers (Part 1)
Big Blue's Attempt at Recapturing The PC Market
The IBM PS/2 Family of Computers. Image From Wikipedia.
After a one-year
hiatus from the my PC articles covering the evolution of the PC, I'm
resuming them starting with the IBM PS/2 family of computers. These
series of computers, introduced in 1987 and continuing into the early
90's, were intended on reestablishing IBM's dominance over the PC
market.
At this point, IBM was still the largest PC manufacturer. However, they didn't control the PC standard anymore; they were just active participants in it, like the various other clone makers. Big Blue had been slowly loosing market-share over the years to these clone-makers as well as more intense competition from various platforms as well, like the Apple Macintosh.
As a result, IBM was going to create a new platform that would reestablish it's control over the marketplace. This would be done with, for it's time, very advance technology. The company would embrace the latest Intel processors along with those motherboards that could accommodate them. These boards would incorporate a new bus architecture in the form of MCA. The Micro-Channel Architecture were much faster than the ISA slots used in the XT and AT-clones. The adapters in these these slots could also be configured via a starter disk with configuration programs, without having to deal with jumpers of those ISA cards. This would make the system easier to configure and avoid interrupt conflicts. A interrupt conflict is when two cards on the motherboard are trying to use the same resources at once, which leads to a conflict.
Introduced in 1987, these computers were very advance for there time. These systems introduced the PS/2 mouse and keyboard ports, which outlasted the series itself. 3-1/2 floppies and there drives were moving from novelty to general-purpose use with them being standardized in the PS/2. Most of the early models carried the 720-KB Double Density (DD) drives with later models incorporating the 1.44-MB High density (HD) floppy disk drives. Also introduced alongside the PS/2 Computers was the new VGA standard. VGA (Video Graphics Array) was a vast improvement over the EGA (Enhanced Graphics Adapter) standard found in the IBM PC/AT computers. VGA introduced the following graphics modes:
320 by 200, 256 colors
640 by 480, 16-colors.
Later on, IBM introduced the 8514 display adapter, which was was one of the first graphics accelerators for PC's, along with the XGA (Extended Graphics Adapter) SVGA standard, which provided higher-resolution graphics modes.
There would be various models as this line intended to be a whole family of computers, from the entry level to the powerful workstations. While selling in fair number, these machines failed to re-establish IBM's control of the market for various reasons.
Many of these computers are emulated on the PCEM emulator now. We can try them out first hand to see how they were like and how they needed to be configured.
At this point, IBM was still the largest PC manufacturer. However, they didn't control the PC standard anymore; they were just active participants in it, like the various other clone makers. Big Blue had been slowly loosing market-share over the years to these clone-makers as well as more intense competition from various platforms as well, like the Apple Macintosh.
As a result, IBM was going to create a new platform that would reestablish it's control over the marketplace. This would be done with, for it's time, very advance technology. The company would embrace the latest Intel processors along with those motherboards that could accommodate them. These boards would incorporate a new bus architecture in the form of MCA. The Micro-Channel Architecture were much faster than the ISA slots used in the XT and AT-clones. The adapters in these these slots could also be configured via a starter disk with configuration programs, without having to deal with jumpers of those ISA cards. This would make the system easier to configure and avoid interrupt conflicts. A interrupt conflict is when two cards on the motherboard are trying to use the same resources at once, which leads to a conflict.
Introduced in 1987, these computers were very advance for there time. These systems introduced the PS/2 mouse and keyboard ports, which outlasted the series itself. 3-1/2 floppies and there drives were moving from novelty to general-purpose use with them being standardized in the PS/2. Most of the early models carried the 720-KB Double Density (DD) drives with later models incorporating the 1.44-MB High density (HD) floppy disk drives. Also introduced alongside the PS/2 Computers was the new VGA standard. VGA (Video Graphics Array) was a vast improvement over the EGA (Enhanced Graphics Adapter) standard found in the IBM PC/AT computers. VGA introduced the following graphics modes:
320 by 200, 256 colors
640 by 480, 16-colors.
Later on, IBM introduced the 8514 display adapter, which was was one of the first graphics accelerators for PC's, along with the XGA (Extended Graphics Adapter) SVGA standard, which provided higher-resolution graphics modes.
There would be various models as this line intended to be a whole family of computers, from the entry level to the powerful workstations. While selling in fair number, these machines failed to re-establish IBM's control of the market for various reasons.
Many of these computers are emulated on the PCEM emulator now. We can try them out first hand to see how they were like and how they needed to be configured.
IBM PS/2 Model 25
IBM PS/2 Model 25. Image From Wikipedia
I've seen one of
these computers in the wild, even though it didn't work. The Model 25
was IBM's take on the Macintosh Classic. This computer was a all-in-one
that has the floppy drives, computer, and monitor built-in.
The PC was powered by a Intel 8086 processor running at 8 MHz. Because the machine came with the Intel 8086, the only Operating System that it could run was DOS. The Model 25 had a MCGA display built-into the computer. MCGA was basically a subset of the VGA standard. However, the MCGA standard only supported 640 by 480 in bit-mapped, along with the low-res 320 by 200, 256 color mode. The 640 by 480, 16-color mode wasn't supported in this model. Most machines shipped with the grey-scale monitor, so even colors were displayed as shades of gray. The base computer came with a 720KB 3-1/2 inch disk drives with a empty bay for another floppy drive or optional hard-disk. The floppy drives could be upgraded to a 1.44 or 2.88MB ones as well. The LGR video showed that a external hard-disk could be connected to the system via a SCSI cable connected to a expansion card installed in the system.
The Model 25 was a entry-level machines. Even though it had the PS/2 branding, this machine didn't have the defining features that was touted in the series, MCA expansion slots. The PC from both the hardware and software standpoint had more things in common with a XT-clone than a PS/2-class machine.
As noted in the Old-Computers.com article, the Model 25 became very popular in the business/corporate setting, but was never embraced within the home market. The all-in-one design, combined with its IBM-branding, secured it's place within the corporate office. Apple never had a strong presence within the corporate market, with business users perceiving that Apple didn't understand there needs, unlike IBM. Compatibility with the important applications, like Lotus 123 and WordPerfect, was a must.
Despite this, the machine was a failure in the home market, where users that were moving away from there 8-bit computers like the Commodore 64 and were buying IBM clone PC's made by DTK, Tandy, and Leading Edge, using computers parts that were often made in Taiwan. These machines were also compatible with those business applications that ran on the IBM computers.
This machine isn't emulated in PCEM.
The PC was powered by a Intel 8086 processor running at 8 MHz. Because the machine came with the Intel 8086, the only Operating System that it could run was DOS. The Model 25 had a MCGA display built-into the computer. MCGA was basically a subset of the VGA standard. However, the MCGA standard only supported 640 by 480 in bit-mapped, along with the low-res 320 by 200, 256 color mode. The 640 by 480, 16-color mode wasn't supported in this model. Most machines shipped with the grey-scale monitor, so even colors were displayed as shades of gray. The base computer came with a 720KB 3-1/2 inch disk drives with a empty bay for another floppy drive or optional hard-disk. The floppy drives could be upgraded to a 1.44 or 2.88MB ones as well. The LGR video showed that a external hard-disk could be connected to the system via a SCSI cable connected to a expansion card installed in the system.
The Model 25 was a entry-level machines. Even though it had the PS/2 branding, this machine didn't have the defining features that was touted in the series, MCA expansion slots. The PC from both the hardware and software standpoint had more things in common with a XT-clone than a PS/2-class machine.
As noted in the Old-Computers.com article, the Model 25 became very popular in the business/corporate setting, but was never embraced within the home market. The all-in-one design, combined with its IBM-branding, secured it's place within the corporate office. Apple never had a strong presence within the corporate market, with business users perceiving that Apple didn't understand there needs, unlike IBM. Compatibility with the important applications, like Lotus 123 and WordPerfect, was a must.
Despite this, the machine was a failure in the home market, where users that were moving away from there 8-bit computers like the Commodore 64 and were buying IBM clone PC's made by DTK, Tandy, and Leading Edge, using computers parts that were often made in Taiwan. These machines were also compatible with those business applications that ran on the IBM computers.
This machine isn't emulated in PCEM.
Model 30
PS/2 Model 30 (PCWorld).
This computer was
very prominently featured in advertisements and print media of the PS/2
when introduced in 1987. This entry-level model was widely regarded as
the flagship for the new family of computers. I admit that from the
pictures, it looks like a very attractive business computer. The design
fits in very well within the corporate setting.
There were two versions of this computer. The first model, like the Model 25, used a Intel 8086 processor running at 8MHz. Because the 8086 lacked a protected mode for more advance operating systems, this restricted the OS options just to DOS. The second model incorporated a Intel 286 processor operating at 10MHz. The more advance features of the 286 allowed the machine to run OS/2 as well. Like the Model 25, even though the computer had the PS/2 branding, it lacked most of the technologies that defined that platform, like the MCA bus slots. It was more in line with a PC/AT-class machine.
The base model came with a 720-KB 3-1/2 inch floppy disk drive which could be upgraded to a 1.44 or 2.88MB Floppy-drive. With a empty bay for another floppy drive or a optional hard-disk (20 or 30MB). It's important to remember that at this time, hard-disk were still a expensive proposition. The vast majority of computers in the home setting didn't have one, while many computers within the corporate setting didn't have one either. The Model 30 could accommodate the 1.44MB high-density floppy disk drives as well.
The Model 30 286 is emulated in PCEM. I needed to download the reference disk for the computer. These disk are needed to configure the various aspects of the computer, like the hard-disk and BIOS settings. These disk images were widely available from IBM's ftp site back in the day. However, the images are now hosted on various FTP sites and PS/2 enthusiast pages. However, the disk image won't work in the emulator because while the configuration program will run, the drivers, in the form of ADF files on the disk, won't recognize the hard-disk controller. On the PCEM forum, there is a modified ADF file which recognizes the disk-drive setting. The file can be injected onto the floppy image via WinImage, overwriting the file currently there. After running the configuration program, the hard-disk will be recognized. On the PCEM emulator, one can also use the XT-IDE bios (AT variety) to use the hard-disk image as well.
The settings are necessary if you want to install DOS or OS/2 onto the emulated computer. I used the disk images for IBM PC-DOS Version 3.3, which originally shipped on the computer. Since the largest partition size supported by DOS 3.3 is 32MB's, I created a 32MB Hard-Disk image for use with the emulator. Two actually as the OS/2 image was partitioned and formatted by DOS as well. For some reason, the installation program for OS/2 Version 1.0 can't partition or format the hard-disk. However, this version of OS/2 still recognizes the partitions and the FAT (File Allocation Table) format used by DOS 3.3.
Like the Model 25, the Model 30 supported the MCGA video standard. That meant that in theory, the computer supported only the 320 by 200, 256 color mode along with 640 by 480, monochrome mode. However, the PCEM emulator is using a standard VGA display adapter. This means that the emulated computer is can use all the video modes provided by VGA.
I'm using a older build of PCEM shown from the screenshots. The older build let me set the CPU clock for the 286. This made the system faster, but less accurate from a historical standpoint. I'm impatient! However, the newer builds will just work nicely and actually are recommended. The system bios files for these systems don't come with the emulator as they are still intellectual property of IBM. As a result, these files will need to be dumped from a real machine. A clever search on Google can turn these files up as well.
There were two versions of this computer. The first model, like the Model 25, used a Intel 8086 processor running at 8MHz. Because the 8086 lacked a protected mode for more advance operating systems, this restricted the OS options just to DOS. The second model incorporated a Intel 286 processor operating at 10MHz. The more advance features of the 286 allowed the machine to run OS/2 as well. Like the Model 25, even though the computer had the PS/2 branding, it lacked most of the technologies that defined that platform, like the MCA bus slots. It was more in line with a PC/AT-class machine.
The base model came with a 720-KB 3-1/2 inch floppy disk drive which could be upgraded to a 1.44 or 2.88MB Floppy-drive. With a empty bay for another floppy drive or a optional hard-disk (20 or 30MB). It's important to remember that at this time, hard-disk were still a expensive proposition. The vast majority of computers in the home setting didn't have one, while many computers within the corporate setting didn't have one either. The Model 30 could accommodate the 1.44MB high-density floppy disk drives as well.
The Model 30 286 is emulated in PCEM. I needed to download the reference disk for the computer. These disk are needed to configure the various aspects of the computer, like the hard-disk and BIOS settings. These disk images were widely available from IBM's ftp site back in the day. However, the images are now hosted on various FTP sites and PS/2 enthusiast pages. However, the disk image won't work in the emulator because while the configuration program will run, the drivers, in the form of ADF files on the disk, won't recognize the hard-disk controller. On the PCEM forum, there is a modified ADF file which recognizes the disk-drive setting. The file can be injected onto the floppy image via WinImage, overwriting the file currently there. After running the configuration program, the hard-disk will be recognized. On the PCEM emulator, one can also use the XT-IDE bios (AT variety) to use the hard-disk image as well.
The settings are necessary if you want to install DOS or OS/2 onto the emulated computer. I used the disk images for IBM PC-DOS Version 3.3, which originally shipped on the computer. Since the largest partition size supported by DOS 3.3 is 32MB's, I created a 32MB Hard-Disk image for use with the emulator. Two actually as the OS/2 image was partitioned and formatted by DOS as well. For some reason, the installation program for OS/2 Version 1.0 can't partition or format the hard-disk. However, this version of OS/2 still recognizes the partitions and the FAT (File Allocation Table) format used by DOS 3.3.
Like the Model 25, the Model 30 supported the MCGA video standard. That meant that in theory, the computer supported only the 320 by 200, 256 color mode along with 640 by 480, monochrome mode. However, the PCEM emulator is using a standard VGA display adapter. This means that the emulated computer is can use all the video modes provided by VGA.
I'm using a older build of PCEM shown from the screenshots. The older build let me set the CPU clock for the 286. This made the system faster, but less accurate from a historical standpoint. I'm impatient! However, the newer builds will just work nicely and actually are recommended. The system bios files for these systems don't come with the emulator as they are still intellectual property of IBM. As a result, these files will need to be dumped from a real machine. A clever search on Google can turn these files up as well.
Since this article
is starting to get very lengthy, I will cover the other systems in part
2, along with the reasons why the PS/2 Family of computers never
dominated and why MCA never caught on. OS/2 will be covered in more
detail as well.
Work Cited:
PCEM - https://pcem-emulator.co.uk/
PCEM Forum: PS/2 resources (For the ADF files) - https://pcem-emulator.co.uk/phpBB3/viewtopic.php?t=676
IBM Personal System/2 -https://en.wikipedia.org/wiki/IBM_Personal_System/2
VGA - https://en.wikipedia.org/wiki/Video_Graphics_Array
Old Computers : IBM PS/2 Model 25 - http://www.old-computers.com/museum/computer.asp?st=1&c=1183
IBM PS/2 (Model 30) - Technical specifications - http://ps-2.kev009.com/pcpartnerinfo/ctstips/7492.htm
Centre for Computing History : IBM PS/2 Model 30 286 - http://www.computinghistory.org.uk/det/2585/IBM-PS-2-Model-30-286/
IBM PS/2 Files (For the Starter Disk Images) - http://www.walshcomptech.com/selectpccbbs/
PCEM - https://pcem-emulator.co.uk/
PCEM Forum: PS/2 resources (For the ADF files) - https://pcem-emulator.co.uk/phpBB3/viewtopic.php?t=676
IBM Personal System/2 -https://en.wikipedia.org/wiki/IBM_Personal_System/2
VGA - https://en.wikipedia.org/wiki/Video_Graphics_Array
Old Computers : IBM PS/2 Model 25 - http://www.old-computers.com/museum/computer.asp?st=1&c=1183
IBM PS/2 (Model 30) - Technical specifications - http://ps-2.kev009.com/pcpartnerinfo/ctstips/7492.htm
Centre for Computing History : IBM PS/2 Model 30 286 - http://www.computinghistory.org.uk/det/2585/IBM-PS-2-Model-30-286/
IBM PS/2 Files (For the Starter Disk Images) - http://www.walshcomptech.com/selectpccbbs/
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