IBM PC/XT, IBM model 5160

Released 1981: The IBM Personal Computer/XT (model 5160, often shortened to PC/XT) is the second computer in the IBM Personal Computer line, released on March 8, 1983. Except for the addition of a 10 MB hard drive as standard, and extra expansion slots, it is very similar to the original IBM PC model 5150 from 1981. IBM did not specify an expanded form of “XT” on the machine or in documentation, but some publications expanded the term as “eXtended Technology” or just “eXTended”.

Facts

  • Type: Personal computer
  • Manufacturer: IBM
  • Released: March 8, 1983
  • Discontinued: April 1987
  • OS: IBM PC DOS, IBM BASIC, PC/IX, SCO Xenix, Minix
  • CPU: Intel 8088 @ 4.77 MHz
  • Memory: 128 KB up to 640 KB RAM
  • Video : IBM MDA (monochrome) or IBM CGA (color), expandable
  • Audio: PC speaker (1 bit)
  • Input: IBM Model F 83-key keyboard (XT keyboard)
  • Removable storage: 1 x 360KB 5.25″ floppy drive
  • Internal storage: 10 MB hard drive (expandable)
  • FPU: Optional Intel 8087
  • Expansion slots: 8 x ISA-8 bit, optional IBM 5161 Expansion unit
  • I/O: Optional serial and parallel ports
  • Predecessor: IBM Personal Computer
  • Successor: IBM Personal Computer/AT, IBM Personal Computer XT 286

The XT was regarded as an incremental improvement over the PC and a disappointment compared to the next-generation successor that some had anticipated. Compared to the original IBM PC, the XT has the following major differences:

  • Expansion slots increased from five to eight.
  • Memory is increased to at least 128KB RAM.
  • 10MB hard disk drive is included as standard equipment.
  • PC DOS 2.0 included. (Offers a 9-sector floppy disk format, 180KB/360KB (single/dual-sided), compared to the 160KB/320KB provided by the 8-sector format of previous releases.)

The XT was not offered in a floppy drive-only model for its first two years on the market. At that time, in order to get a second floppy drive, the user had to purchase the 5161 expansion chassis.

I’ve written an own article about IBM PC DOS, see: The History of DOS

Expansion (ISA slots)
The number of expansion slots in the original IBM PC was a limiting factor, since needed components such as the video controller, disk controller and printer interface came as separate expansion cards and could quickly fill up the five available slots, requiring the user to swap cards in and out as tasks demanded. The XT addressed the problem by adding three extra expansion slots for a total of eight. While the slots themselves are identical to those in the original PC, the amount of physical space in the chassis differs, so two of the new slots cannot accept full-length cards. In addition, the spacing of the slots is narrower than in the original PC, making it impossible to install some multi-board cards.

Reception
The XT was well received, although PC DOS 2.0 was regarded as a greater improvement than any of the hardware changes, and by the end of 1983 IBM was selling every unit they made. The Compaq Portable also came out in March 1983, and would prove a popular competitor. It’s sometimes referred to as the “first PC clone”, but already before this, in June 1982, the Columbia Data Products’ MPC 1600 “Multi Personal Computer” was available. Other “clones” included the Seequa Chameleon, the Hyperion, Eagle Computer’s Eagle 1600 and the Corona PC. The latter two companies were sued by IBM and settled out of court, agreeing to re-implement their BIOS in a way that did not violate IBM’s copyrights. The IBM PC/XT was discontinued in the spring of 1987.

My IBM Personal Computer/XT

I’ve swapped a Commodore C128 for my IBM PC 5160. The machine worked great and booted up with the .

The error codes was for memory, keyboard and harddisk or harddisk controller.

Harddisk: The harddisk was not spinning up either and appeared dead. I’ve removed the harddisk logic board and rotated the spindle clockwise by hand and also put a very small drop of oil on the axis. After this, the harddisk was spinning up, but there was a “clicking” noise and I still got the 1701 error code. So I decided to remove the harddisk controller.  I will use a modern XT-IDE card with an IDE-CF card adapter instead of the old harddisk.

Keyboard: After some inspection, it turned out, the DIN connector for the keyboard on the motherboard needed to be re-soldered.

Memory: The DIP-switch configuration for the memory was wrong, after sorting this out I still got 4098 201 error code. First I though it was re-reseating the RAM chips in its sockets that fixed it, but found out the DIP switches was worn and need to be tickled with to get rid of the error. So I need to replace those two SW1 and SW2.

IBM Personal Computer/XT

Remi Jakobsen


I'm collecting classic computers and video games, stretching from the 70's into the 90's. Restoration, history, usage ...


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