IBM 5110

IBM 5110 is a barely-portable computer that was announced in January 1978 []. Our system is not in a perfectly working condition.


The system is huge and heavy. The chassis feels extremely sturdy, and it contributes to the system's weight. Several controls are on the front panel. Our system does not have the optional tape drive. The power switch is also on the front panel. This is an APL-only model, and the keyboard has special APL symbols.
IBM 5110 portable computer Front control panel of IBM 5110 Keyboard of IBM 5110

External I/O is on the back of the system. There are ports for video-out and storage options. IBM logo is on the top of the system.
Back of IBM 5110 IBM logo on 5110

The message of death. The second screenshot is the register dump. One reader named mikoto0931 kindly told us that he repaired his 5100 using BW-100 contact cleaner, but cleaning the card contacts didn't help. According to page 4-10 of [2], the ERROR 001 means that the ROS control card at F2 is malfunctioning.
Error message from 5110 Register dump of 5110

Internal Modules

All components in the system connect to the backplane board. The board is built using wire-wrapping in addition to printed circuit traces. Each slot is labeled A to N where I is missing. Slot A is the nearest to the rear of the system, and a card with I/O interface is installed there.
cards in 5110 backplane is wire-wrapped

The card at slot M (Read/Write storage):
slot M solder side

The card at slot L (Executable ROS):
Slot L

The card at slot K (Feature ROS):
slot K

The card at slot J (Controller) and H (Base I/O) are connected using two jumpers that resemble SLI bridges.
card J card H solder side of card H

The card at slot G (Display):
card G

The card at slot F (ROS Control):
card F solder side

The card at slot E (APL ROS):
card E


  1. Details about the technology of this computer []
  2. IBM: IBM 5110 Computer Maintenance Information Manual. SY31-0550-1