In these days of multi-gig OSes, we cast our eyes back to something both much bigger and much smaller.
The Reg FOSS desk only recently came across interesting news about a very cool project: Jürgen Müller’s LittleGP-30, a 2017 recreation on an FPGA of the Librascope LGP-30, a seminal early computer from the 1950s. What especially tickled our fancy is that the tiny replica is complete with a nearly full-sized version of the desk-sized original’s controls.
This desktop-calculator sized unit is a re-implementation of the Librascope LGP-30, launched by Royal McBee in 1956. The modern version is based on a roughly $65 Numato Mimas development board. To this, Müller added a tiny LED display, where the original, ingeniously, had a built-in oscilloscope hidden behind a tiny screen with cutouts to reveal the contents of the registers.
Müller told The Register:
Obsolescence Guaranteed has sent the Reg FOSS desk a PiDP-10 console and we are currently experimenting with it. A write-up is coming soon.
The original machine is a chunky beast, but with an amazingly frugal design from 1954. The marketing brochure [PDF] is only 12 pages long, and we enjoy its blend of computer specs and stats with 1950s design:
- LOW COST
- SMALL SIZE… MOBILE
- SIMPLIFIED PROGRAMMING
- LARGE MEMORY
- RELIABLE PERFORMANCE
This “small size” machine was 84×112×66 cm (33×44×26 inches), weighed 360 kg (800 lb), and cost a little under $50,000 in 1956. Or, 69 years later, $550,000 – or £425,000. This bargain price meant that hundreds of units were sold. It is built from vacuum tubes and diodes, but fewer of them than you might expect given its massive 4 kilowords of memory: just 113 valves and under 1,500 diodes.
This is because the machine’s working memory is on a magnetic drum spinning at 3,700 rpm: 64 tracks of 64 sectors, holding 4,096 31-bit words. The processor is bit-serial which partly explains why so few electronic components are involved. You can see pictures of the drum and other parts, such as the modified Flexowriter typewriter it used for I/O, plus an explanation of the instruction set, in LGP-30 — A Drum Computer of Significance.
Some consider it to be the first minicomputer, and there’s also some personal anecdotes about the machine.
With all its memory being on a drum, access times were not just quite slow, they were also very important to know: the next word in memory took 0.26 milliseconds to access. The timing is significant because this is the computer described in Ed Nather’s celebrated Story of Mel, a Real Programmer.
The Story of Mel has been passed around the internet since before the Web existed: Nather posted it to news:net.followup in 1983. Even this annotated version keeps the free-verse style formatting, which is just an artefact of its long journey across many formats over 42 years.
There are also several close dissections of the code and its astonishing timing loop. The story even got its own site: The Story of Mel – 40th Anniversary. There are many analyses of how the code worked, which Müller anatomizes.
Many decades later, the man behind the myth was traced and identified: Mel Kaye – CV. He was born in 1931, and he died in 2018, just the year after Müller’s remarkable replica machine was revealed. We really hope that he got to read about it.
That is not the end of the influence of the LGP-30, though. Your vulture was lucky enough to get to touch one – briefly, before being told off – in the Moravian Gallery’s 2018 exhibition 1968:computer.art. The first computer in the city of Brno, it was used by Czech artist Zdeněk Sýkora to create some of the first ever procedurally-generated computer art [PDF]. While not a household name, Sýkora’s art can still be seen around his homeland, and he got an obituary in the Guardian.
The famed Apollo program project lead Margaret Hamilton also cut her coding teeth on one. One of the direct ancestors of BASIC, the DOPE programming language, ran on one, too. ®
