Daves Old Computers
IBM 5100

The IBM 5100 is considered to be the first commercial portable computer, and is nearly the first personal computer, having been beaten to market by the Mits Altair by only a few months. Even so, it would never have been considered a "home computer" due to it's high price of $10,000-$20,000 USD depending on configuration. Weighing over 50 lbs, it would not seem very portable by todays standards, however when it was released in 1975, it was smaller (and lighter) than anything else that was available.

The 5100 was the first in a series of small computers, which six years later produced the 5150 PC, and the rest as they say ... is history.

The 5100 is one of the few machines currently in the collection which is not based on a microprocessor chip. The CPU in the 5100 is a board full of high density logic (for the time) called PALM, which stands for "Put All Logic in Microcode". The PALM processor uses stored microcode to implement a subset of the IBM System/360 CPU architecture, which in turn runs the native language from ROS (Read Only Storage). Here is a picture of a 5100 logic module, showing the large proprietary IBM devices.

The 5100 was available in several configurations, which included native BASIC, APL or BOTH, and RAM configurations from 16k to 64k. The machine in my collection is a "low-end" 5100, having only the BASIC language ROS, and 16k of random access memory.

The 5100 provided a cartridge tape drive as it's only permanent storage. Later models included the 5110 with external 8" floppy drives, and the 5120 which incorporated a internal floppy drive.

The IBM was donated by Markus Wandel. (Many thanks Markus for this rare and historic machine).

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

The IBM 5100, the worlds first commercial portable computer.

Closeup of the front panel. The APL version of this machine has different keytops which include the APL characters. The APL/BASIC version adds an APL/BASIC switch in the position between "Reverse Display" and "Restart".

Right side view of IBM 5100.

Left side view of IBM 5100.

Rear view of IBM 5100. The cover plate is for optional interfaces, including a serial port.

This "straight on" view allows you to see the heads inside the tape drive.

Bottom view of IBM 5100.

Closeup of the information label on the bottom of the unit.

Here is the complete documentation set which accompanies my 5100. Some of these are already available as PDF's, and I have PDF's of the 5110 versions of some, which are very similar. As time permits, I will scan the remaining documents.

I even have the IBM Incident Report Log Book for this unit.

Here are a couple of the original IBM distribution tapes.

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