IBM 5100 Personal Computer

Daru’s Notebook

Click image to read the IBM 5100 origin story!

The IBM 5100 combines two legacy “line printer” systems into a more compact “CRT-based” system, with a compact digital data-storage tape unit.

The IBM 5100 “Executable ROS” is written in PALM instructions and interprets the code used by these legacy systems, which was a concept inherited from the IBM System/360 (see here). None of the public IBM manuals use the term PALM, but that term is used in an internal IBM technical publication (GENASM 1977). Shown below is a description from the Maintenance Information Manual (which uses the term “internal machine microcode”):

IBM engineers resolved the external power supply size issue that was in the SCAMP prototype and designed an elaborate internal clam-folding design to support all the cards of the system within a small case. In addition, IBM incorporated an improved “solid state storage” used for ROS/ROM storage of microcode. This was an evolved version of the prior SLT (solid logic technology) from a few years earlier and was key to how the IBM 5100 was made into a truly portable and “instant-on-and-ready” system (with over 128KB of built-in ROS/ROM software).

Special Topics

General Features of the IBM 5100

Other references

Exploring the 1978 IBM 5110 here
Exploring the 1980 IBM 5120 here
Exploring the 1981 IBM PC 5150 here
IBM 5110 online emulator here (JavaScript)
C source to PALM emulator here (Wintel prebuilds available, text-mode)
Collection of IBM 5100/5110/5120 relocated PDF documents here (github)
IBM 5100 PDF documents here (bitsavers)
IBM 5110 PDF documents here (bitsavers)
The IBM 5110 System Logic Manuals in high resolution here (github)
Excellent article about the IBM System/3 is here (from a part of the development team)
Excellent IBM 5110 Info at Informatik Computer Museum in Germany here

1975 article in Datamation magazine introducing the IBM 5100 (page 73): 197511.pdf (

A microprocessor-based portable computer: The IBM 5100 | IEEE Journals & Magazine | IEEE Xplore

ยป The IBM PC, Part 1 The Digital Antiquarian (

IBM paperweight teardown: Reverse-engineering 1970s memory chips (


IBM 5100 Tape Usage demo here
IBM 5110 Wintel-based Command Line Emulator here
IBM 5110 Ball Bounce DCP demo here (brief alternate for 5100)
IBM 5100/5110 MCU-based Keyboard Replacement here
IBM 5110 QIC Tape Motor Demo here
IBM 5110 CRT internals demo (fixing lines, silly things at end) here

Other Topics
DestinyHunter for Commodore PET
Mural of History of Personal to Home Computers here

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