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PS/1

Also known as	PS/1000 (Europe)
Type	Personal computer
Release date	August 1990
Discontinued	1994
Predecessor	PCjr
Successor	Aptiva
Related	PS/2

ThePS/1 (known in some European countries as thePS/1000^[1]: 95) is a brand for a line ofpersonal computers that markedIBM's return to the home market in 1990, five years after theIBM PCjr. It was replaced by theIBM Aptiva in September 1994.

The PS/1 line was created for new computer users and was sold in consumer electronics stores alongside comparable offerings fromCompaq,Hewlett-Packard,Packard Bell, and others. American PS/1 models came with amodem installed so users could access online IBM help services, which were provided by partnerships withProdigy andQuantum Computer Services.

Like the PCjr, the PS/1's name suggested a more limited machine than IBM's business line, thePS/2. However, unlike the PS/2, the PS/1 was based upon architecture closer to theAT and compatibles, for example usingISA, plainVGA, andIDE. Although the first models used custom-designed components and design, later desktop andtower models used mostly standard components. The earlier models included aROM with IBM's PC DOS and agraphical shell, however the system was compatible with other DOS implementations and the shell could be installed on the hard drive. Later models included a feature called "Rapid Resume"^[2] which gave the computers the ability to go into standby mode as well as ahibernation function. There were several form factors used during the PS/1's production, with the 2133 and 2155 cases used for several model years, while the 2168 tower case was offered later in later models of the PS/1 lineup:

• 2011 Proprietary design, power supply is withinCRT
• 2121 Proprietary design, power supply is within CRT, up to two available ISA slots
• 2123 Limited-production model. Based on IBM PS/2 model 30 case, three available ISA slots
• 2133 Desktop case. The 3x3 references the available slots anddrive bays.
• 2155 Desktop case larger than 2133. The 5x5 references the available slots and drive bays, including a 5.25" bay.
• 2168 Tower unit. The 6x8 references the available slots and bays, including 5.25" bays.

IBM PS/1 (model 2011)

Release date	1990; 35 years ago (1990)
Operating system	PC DOS 4.01 (in ROM)
CPU	Intel 80286 @ 10MHz
Memory	512 KB ~ 2.5 MB

IBM PS/1 (model 2121)

Release date	1992
Discontinued	1993
Operating system	PC DOS 4.01 (in ROM)
CPU	Intel80386SX @ 16 MHz ~ 20 MHz
Memory	2 MB ~ 6 MB

The original PS/1 (Model 2011), based on a 10 MHzIntel 80286CPU, was designed to be easy to set up and use. It featured 512 KB or 1 MB of on-board memory (expandable to 2.5 MB with proprietary memory modules), built-in modem (in American models only) and an optional 30 MB hard disk. Later models had an optional 40 MB hard disk. IBM also released a 5.25" disk drive unit, a $169 expansion box called Adapter Card Unit (ACU)^[3] that could hold three 8/16 bitISA third-party expansion cards. A $995CD-ROM drive, based on aWestern DigitalSCSI chip, could be fitted underneath the case.^[4] The first generation of PS/1 models suffered from very limited expansion capabilities, since they lacked standardISA expansion slots, unless you bought the expansion box (ACU). You could however add up to three $199 512 Kb memory cards, that was easy to install. The original offering was 4 models:

• $999 VGA Mono (640x480), 512 Kb RAM
• $1.499 VGA Color (640x480), 512 Kb RAM
• $1.699 VGA Mono (640x480), 1 Mb RAM, 30 Mb hard disk
• $1.999 VGA Color (640x480), 1 Mb RAM, 30 Mb hard disk

The 2121 series computers used the same form factor as the 2011 series, but included up to two ISA slots inside the case. Memory could be expanded from 2 MB to 6 MB using a proprietary 4 MB memory module. The higher-end 2121 featured anIntel 80386SX processor running at 16 or 20 MHz.

The 2121 series PS/1 computers can be split into the following major hardware categories:^[4][5]

Monitors:IBM made the decision to put theDC power supply in the monitor, making use of third-party monitors difficult and essentially impractical and limiting the usefulness of the computer if the monitor needed service (similar to the problems of theColeco Adam andAmstrad 1512 years earlier). Some models were sold with greyscale VGA monitors. However, some hobbyists could manage to remap thepinouts to allow for third-party monitors.

"DOS in ROM”:Similar to a fewTandy 1000 models, the early 2011 and 2121 had anoperating system (PC DOS 4.01) built into ROM, rather than loading it from ahard drive. The ROM disk would then load a "4-quad" screen which allowed users to access help, rapidly launch pre-installed software, connect online, and access files on the hard drive. It was possible to have the computer boot from the hard drive if the operating system was upgraded, and IBM provided aDOS 6.22-compatible version of the "4-quad" program that could be launched from the hard drive if users wished to continue using it.^[6]

The 2133 series PS/1 computers can be split into the following major hardware categories:^[7][8]

European models^[9]

US models^[10][11][12]

On May 11, 1993, IBM introduced a "new generation" of the PS/1 line.^[14] Later PS/1s featured standardLPX-architecture motherboard. Many of these later PS/1s shipped from the factory withMS-DOS andMicrosoft Windows, rather than IBM'sPC DOS orOS/2. An early 2133 model did come preloaded with OS/2 2.1. This was because IBM targeted OS/2 for high-end computing machines with more power.

The PS/1 line was discontinued in 1994 and replaced with theAptiva line, which was architecturally very similar to the later models of the PS/1, but with a more marketing-friendly name. Aptivas were sold in the United States until early 2000, when price pressures made the line unprofitable and IBM withdrew from the retail desktop PC market entirely.

Timeline of the IBM Personal Computer v t e
Asterisk (*) denotes a model released in Japan only

• IBM Archives: IBM PS/1

• X86 IBM personal computers
• Products introduced in 1990
• 8086-based home computers
• Computer-related introductions in 1990

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