"The IBM 5100 Portable Computer, introduced on September 10, 1975, was one of the earliest attempts to shrink mainframe-style power into a transportable system. Evolving from the 1973 SCAMP prototype—built at IBM’s Los Gatos Scientific Center—the 5100 brought APL and BASIC computing to a single-user machine that weighed 25 kg and cost between $8,975 and $19,975. Although marketed as “portable,” it required mains power, yet its integrated design was groundbreaking: a 5-inch CRT, keyboard, tape drive, system ROM, and up to 64 KB of RAM housed in a suitcase-sized enclosure.
At its core was IBM’s 16-bit PALM processor, capable of addressing 64 KB directly and using bank switching for larger configurations. The machine’s ROM contained full interpreters for APL and BASIC—adapted from IBM’s System/370 and System/3 environments—enabled by microcode emulation. This allowed the 5100 to run software from larger IBM systems without redesign.
The 5100 offered QIC tape storage, optional external printers or typewriters, and a communications adapter emulating an IBM 2741 terminal. Users could connect an external monitor via BNC, and models supporting both languages included a hardware toggle to switch between APL and BASIC.
Withdrawn in 1982 after the release of the IBM 5110 and 5120, the IBM 5100 remains a pioneering milestone, representing IBM’s first practical step toward personal computing through portability and microcode-based compatibility."
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@vidak @mplouffe This was an amazing machine. But for the price and availability, it could have qualified as the first personal computer, and the tiny screen made it far less appealing than devices with external 9” or 12” monitors. But it pioneered BASIC in ROM, which is what made the Apple II and Commodore PET popular; and APL was a truly esoteric twist, available at literally the flip of a switch.
Fun fact: 1981’s IBM PC was numbered the 5150 as it was nominally a follow-on to the 5100.
@vidak Here's the real thing, instead of just a cardboard mock-up of one: https://www.youtube.com/watch?v=-7Xj2263lhA
@vidak I'm really curious what kind of tape drive that is. It looks like an 8 track form factor rather than a cassette.
@vidak such machines (IIRC Osborne came out with a similar form factor) were often referred to as "luggables" to underline the limits on their portability.
@Cdespinosa @vidak @mplouffe from a software engineering perspective it's an interesting fact that it was easier for them to implement an emulator for the 360 architecture and run APL/360 on it than reimplementing APL for it.
@loke @Cdespinosa @vidak @mplouffe Based on what i've read from The Early History of Smalltalk (which i recommend btw) it seems like it used to be common to just write an emulator for existing programs/programming languages instead of porting it, even if the result ran much slower, possibly because it was quick to do.
Nowadays people rely alot on x86 compatibility to avoid having to port programs, which in turn makes the ISA more complicated and harder to emulate, both making this less common. Also having cross-compatible source code is probably easier than it used to be.
@cxxvii @Cdespinosa @vidak @mplouffe right, APL/360 was written in assembler, so a port would be a rewrite.
If the priority wasn't performance, implementing an emulator was probably pretty easy since the 360 architecture is pretty simple.
That said, implementing an APL isn't that hard either, but I guess this allowed them to get to market quickly and keep 100% compatibility with with the mainframe version.
