Daves Old Computers - IBM 5100 Disassembled

Here are some photos of the internals of the IBM 5100.

Click any photo to view a large high-resolution image.

Here is the IBM 5100 with the cover off. The cards are hanging upside down from the large backplane that you can see. Note the "RUN" switch beside the monitor. When this switch is OFF, the machine is held in a halt state, and the button beside it allows single-stepping.

Here the card cage is "flipped out" to provide access to the cards.

Here is a closeup of the card cage showing the installed cards.

Rear view of open chassis, which allows you to see the rear of the tape drive and CRT unit.

The IBM 5100 CRT unit. This is a 5 inch monochrome monitor.

The following cards are presented in the order in which they can been seen in the card cage closeup view, front to back:

16k RAM card.

Display card.

Executable ROS (Read Only Storage) card. Note that the left half of this card holds an APL Supervisor extension, and is not populated in this unit (which is BASIC only).

Controller card - this is the main logic of the P.A.L.M CPU. (Put All Logic in Microcode).

Base I/O card.

ROS Adapter card - this card provide an interface to the non-executable ROS which exists outside of the CPU address space.

Non-executable ROS (Read Only Storage) card. Note that the right half of this card holds APL code and is not populated in this unit (which is BASIC only) - in addition, another compete ROS card with both sides populated is required for the APL unit.

Tape controller card - this card is not included in the card cage, but is positioned over the tape deck, which is mounted to the front panel.

Here are some of Markus Wandels original photos of the interior of this machine: Backplane, Card Cage (view 1), Card Cage (view 2), Cooling system, CRT unit.

Back to IBM 5100

Copyright 2004-2005 Dave Dunfield.