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IBM PS/2 Model 50

From Alfawiki
IBM Personal System/2 Model 50
Company typePersonal computer model
IndustryComputer hardware
FoundedApril 2, 1987; 39 years ago (1987-04-02)
Headquarters
Boca Raton
,
United States
ProductsDesktop computer

The Personal System/2 Model 50 represents a mid-tier desktop computer within IBM's Personal System/2 (PS/2) series. Launched in April 1987, it is powered by an Intel 80286 CPU running at 10 MHz. In June 1988, IBM introduced an enhanced version called the Model 50 Z, which featured faster RAM, eliminating wait states and thereby improving overall system performance. The Model 50 became the best-selling unit in the PS/2 lineup for several years, with sales exceeding 440,000 units during its initial year.

Development and release

Debuting on April 2, 1987, alongside the entry-level Model 30 and the higher-tier Model 60, the Model 50 and Model 60 were IBM’s first computers to utilize the proprietary Micro Channel architecture (MCA), intended to succeed the older Industry Standard Architecture (ISA) bus standard. Marketed as a midrange option, the Model 50 was priced at $3,595, compared to $2,295 for the base Model 30 which retained ISA bus compatibility. The Model 50 came in a standard desktop chassis, whereas the Model 60 employed a tower design featuring additional drive bays and expansion slots.

Produced at IBM’s Boca Raton plant in Florida, by June 1987 daily output for the Model 50 reached 1,000 units, surpassing the Model 60’s rate of 800 units per day. Strong demand caused component shortages by the end of that year. Within its first twelve months on the market, IBM sold more than 440,000 units of the Model 50, with forecasts predicting an extra 650,000 units for 1988. By April 1988, it had become the world’s best-selling personal computer and maintained this status through at least late 1989.

Specifications

As the most cost-effective PS/2 model equipped with Micro Channel architecture (MCA) expansion slots, the Model 50 offered four MCA slots compared to eight in the Model 60. Consistent with all MCA-based PS/2 systems, it did not support ISA expansion cards. It was also the least expensive PS/2 to include a Video Graphics Array (VGA) interface, delivering enhanced color capabilities and resolution over previous Enhanced Graphics Adapter (EGA) models. The chassis of the Model 50 measured approximately half the volume of its predecessor, the PC/AT, and housed an Intel 80286 processor clocked at 10 MHz. Following PS/2 design conventions, it incorporated a single 3.5-inch floppy disk drive rather than the older 5.25-inch floppy disk drive.

A key design aspect was its largely tool-free disassembly: two thumbscrews at the rear allowed easy removal of the case lid, while both hard disk and floppy drives were mounted on a platform above the motherboard secured by captive push-pin tabs that could be disengaged using a plastic wedge supplied by IBM. Expansion cards were also secured with plastic thumbscrews for convenient removal.

The original Model 50 utilized DRAM with a 125-nanosecond access time, necessitating wait states that reduced memory performance. On June 2, 1988, IBM released the Model 50 Z variant featuring faster DRAM with an access time of 85 nanoseconds, resulting in roughly a 20% increase in memory and processing speed. The updated model replaced dual SIMM slots with a single slot supporting either 1-MB or 2-MB SIMMs—upgraded from the original’s maximum of 512-KB per slot. Additionally, it offered larger hard drive options of either 30 MB or 60 MB with seek times twice as fast as those of the initial 20-MB drives.

Reception and legacy

Upon its release, the Model 50 garnered a variety of responses. It was commended for its competitive pricing and innovative hardware features but faced criticism due to hardware glitches, sluggish computational performance, and a slow default hard drive. Nevertheless, PC Magazine later acknowledged the Model 50 as one of the most impactful personal computers spanning from the 1980s through the 2020s. This recognition stemmed from its significant contribution to mainstreaming VGA graphics and 3.5-inch floppy disk drives, as well as its pioneering tool-free design that shaped subsequent PC engineering.

Submodels

IBM PS/2 Model 50 submodels
Model IBM P/N Processor Clock speed
(MHz)		 Bus No. of
slots		 No. of
drive bays		 FDD HDD Stock
RAM		 Maximum
RAM		 Video adapter Monitor Form factor Date introduced Notes Ref(s).
50 8550-021 Intel 80286 10 (1 w) MCA, 16-bit 4 3 one 1.44 MB 20 MB (ST-506) 1 MB 1 MB VGA optional Desktop Template:Date table sorting [1][2]
50 Z 8550-031 Intel 80286 10 (0 w) MCA, 16-bit 4 3 one 1.44 MB 30 MB (ST-506) 1 MB 2 MB VGA optional Desktop Template:Date table sorting [3][2]
50 Z 8550-061 Intel 80286 10 (0 w) MCA, 16-bit 4 3 one 1.44 MB 60 MB (ESDI) 1 MB 2 MB VGA optional Desktop Template:Date table sorting [3][2]

References

  1. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named GJAN-43VM6G
  2. ↑ 2.0 2.1 2.2 Cite error: Invalid <ref> tag; no text was provided for refs named bowldspp338339
  3. ↑ 3.0 3.1 Cite error: Invalid <ref> tag; no text was provided for refs named GJAN-43VMLQ
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