IBM Personal System/2
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The Personal System/2 or PS/2 was IBM's second generation of personal computers. The PS/2 line, released to the public in 1987, was created by IBM in an attempt to recapture control of the PC market by introducing an advanced proprietary architecture.
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Technology
IBM's PS/2 was designed to remain software compatible with their PC/AT/XT line of computers upon which the booming PC clone market was built, but the hardware was quite different. PS/2 had two BIOSes. One was named ABIOS (Advanced BIOS) with which OS/2 operating system was running on PS/2. The other was named CBIOS (Compatible BIOS) which was prepared in order for PS/2 to be software compatible with the PC/AT/XT.
Micro Channel Architecture
The IBM Personal System/2 line introduced the Micro Channel Architecture (MCA for short) which was technically superior to the ISA bus and allowed for higher speed communications within the system.
The MCA bus featured many advances that would not be seen in other interface standards until several years later. Transfer speeds were on par with the much later introduced PCI bus standard. MCA allowed one-to-one card to card and multi-card to processor simultaneous transaction management which is a feature of the PCI-X bus format. Busmastering capability, bus arbitration, and true plug-and-play BIOS management of hardware were all benefits to the MCA bus. The MCA bus was also a 32-bit based architecture, as opposed to ISA which was only 16-bit.
In spite of these technical advantages, the Micro Channel Architecture never gained wide acceptance outside of the PS/2 line due to IBM's anti-clone practices and incompatiblities with ISA. IBM offered to sell a Micro Channel licence to anyone who could afford the royalty, but they not only required a royalty for every MCA-compatible machine sold, but also a payment for every IBM-compatible machine the particular maker had ever made in the past.
Peripheral interface
PS/2 systems introduced a new specification for the keyboard and mouse interfaces, which are still in use today and are also called "PS/2". The PS/2 keyboard interface was electronically identical to the long-established AT interface, but the cable connector was changed to a 6-pin mini-DIN interface, as was (for reasons still unexplained) the PS/2 mouse interface. The design decision for identical but incompatible connectors would prove aggravating to consumers until the introduction of the USB protocol in 1996. To help alleviate this, PS/2 keyboard and mouse connectors were later color-coded: purple for keyboards and green for mice as defined by the Microsoft PC 97 standard.
Graphics
Other features were introduced by this new generation of IBM computer systems, such as the change over to the VGA graphics output standard over the previous EGA standard. VGA increased graphics memory to 256K and provided for 640x480 resolutions with 16 colors, and in low-res, 320x200 resolution with 256 simultaneous colors from a palette of 262,144. The 8514 and later XGA were other computer display standards introduced by the PS/2 line. Although the design of these adapters did not become an industry standard as VGA was, their standard resolution (1024 by 768 pixels) and the "XGA" name have been influential on many newer graphics systems.
External storage
Although 3.5" 1.44 megabyte floppy disks were becoming common in the industry by 1987, the PS/2s were the first IBM models to use them as standard. While the disk format itself was standard, IBM chose to use a non-standard form for the disk drives, resulting in very high repair costs as a standard drive could not be retrofitted to a PS/2. (The IBM part was functionally identical to but about five times more expensive than a standard 3.5" floppy drive.) Initially starting out with a 1.44MB capacity, by the end of the PS/2 line, these had standardized at 2.88MB capacity.
Memory
The PS/2 introduced 72-pin RAM SIMMs, which became the de facto standard for RAM modules by the mid-90s in 486 and early Pentium desktop systems. These were 32 or 36 bits wide, and replaced the old 30-pin (8/9 bit) SIMM standard, which was much less convenient as they had to be used 4 or 8 at a time to match the bus width of a given system. 72-pin SIMMs were also capable of larger maximum capacities.
Models
The PS/2 Models 25 and 30 (IBM 8530) were ISA-based (in other words, essentially IBM PC/AT-like systems in a different form factor). The machines had an ESDI hard drive interface and the drives were available as an optional part, however many of these entry-level machines were sold without hard drives due to the high cost. The Model 25 featured an integrated display to compete with the Apple Macintosh as a low-cost computer for educational environments.The higher models were equipped with the Microchannel bus and SCSI hard drives. PS/2 models 50 (IBM 8550-021)and 60 (IBM 8560) used the Intel 80286 processor, the PS/2 models 70 (IBM 8570-81) and 80 used the 80386DX, while the medium-performance PS/2 model 55SX (IBM 8555-081) used the 16/32-bit 80386SX processor.
The PS/2 models 90 (IBM 8590/9590) and 95 (IBM 8595/9595/9595A) used Processor Complex daughterboards holding the CPU, memory controller, Microchannel bus interface, and other system components. The available Processor Complex options ranged from the 20 MHz Intel 80386 to the 90 MHz Pentium and were fully interchangeable. The IBM PC Server 500, which has a motherboard identical to the 9595A, also uses Processor Complexes.
The IBM PS/2E (IBM 9533) was the first Energy Star compliant personal computer. It had a 50 MHz 486SLC processor, an ISA bus, four PCMCIA slots, and an IDE hard drive interface. The environmentally-friendly PC borrowed many components from the ThinkPad line and was composed of recycled plastics, designed to be easily recycled at the end of its life, and used very little power.
Marketing
The PS/2's controversial hardware design was tied to a marketing strategy that was similarly unsuccessful. During the 1980s, IBM's advertising of the original PC and its other product lines had frequently used the likeness of Charlie Chaplin. For the PS/2, however, IBM augmented this character with a notorious jingle that seemed more suitable for a low-end consumer product than a business-class computing platform:
"How ya' gonna' do it? PS/2 It! It's as easy as I.B.M."
Another campaign featured the actors from the television show, M*A*S*H playing updated versions of their characters from the series. [1][2]
The profound lack of success of these advertising campaigns led, in part, to IBM's termination of its relationships with its global advertising agencies; these accounts were reported by Wired Magazine (Issue 3.08, August 1995) to have been worth over $500 Million a year, and the largest such account review in the history of business.
Overall, the PS/2 experiment was a commercial disaster. With what was widely seen as a technically competent but cynical attempt to gain undisputed control of the market, IBM unleashed an industry and consumer backlash. The firm suffered massive financial losses for the remainder of the decade, forfeited its previously unquestioned position as the industry leader, and eventually lost its status as the largest single manufacturer of personal computers, first to Compaq and then to Dell.
For IBM, while the PS/2 experiment was a commercial disaster from a consumer perspective, the platform experienced exceptional success in the business sector where many people still lived with the motto "Nobody ever got fired for buying IBM". Many models of PS/2 systems saw a production life span that took them well into the late 1990s.
