Librascope LGP-30
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The LGP-30, made by the Librascope division of General Precision, Inc., was one of the earliest computers built on a personal scale. It was quite popular with "half a thousand" units sold, starting in 1956.
Technical description
Librascope tried to build a usable computer with a minimal amount of hardware. The single address instruction set had only 23 commands. Not only was the main memory on magnetic drum, but so were the CPU registers, each on a dedicated track.
The drum memory stored 2048 32-bit words. Input and output was by six-level paper tape. The number of vacuum tubes was kept to a minimum by using solid-state diode logic wherever possible. The whole machine was the size of a large desk.
To further reduce costs, the traditional rows of lights showing internal registers were absent. Instead, Librascope mounted a small oscilloscope on the front panel. It displayed the output from the register read heads, allowing you to actually see the bits. Horizontal and vertical size controls let you to adjust the display to match a plastic overlay engraved with the bit numbers.
ACT-III programming language
The LGP-30 had an "Algol-like" high level language called ACT-III. Every token had to be delimited by an apostrophe, making it hard to read and even harder to prepare tapes:
s1'dim'a'500'm'500'q'500'' index'j'j+1'j-1'' daprt'e'n't'e'r' 'd'a't'a''cr'' rdxit's35'' s2iread'm'1''iread'q'1''iread'd''iread'n'' 1';'j'' 0'flo'd';'d.'' s3'sqrt'd.';'sqrd.'' 1'unflo'sqrd.'i/'10';'sqrd'' 2010'print'sqrd.''2000'iprt'sqrd''cr''cr'' ...
Booting the machine
The procedure for booting the LGP-30 was one of the most complicated ever devised. First, one snapped the bootstrap paper tape into the console typewriter, a Frieden Flexowriter, pressed a lever on the Flexowriter to read an address field and pressed a button on the front panel to transfer the address into a computer register. Then one pressed the lever on the Flexowriter to read the data field and pressed three more buttons on the front panel to store it at the specified address. This process was repeated, maybe 6–8 times, and one developed a rhythm:
burrrp, clunk, burrrp, clunk, clunk, clunk, burrrp, clunk, burrrp, clunk, clunk, clunk, burrrp, clunk, burrrp, clunk, clunk, clunk, burrrp, clunk, burrrp, clunk, clunk, clunk, burrrp, clunk, burrrp, clunk, clunk, clunk, burrrp, clunk, burrrp, clunk, clunk, clunk.
You then removed the bootstrap tape, snapped in the tape containing the regular loader, carefully arranging it so it wouldn't jam, and pressed a few more buttons to start up the bootstrap program.
Once the regular loader was in, you were ready to read in your program tape. The regular loader read a more compact format tape than the bootstrap loader. Each block began with a starting address so you could back up the tape and continue reading if an error occurred.
Of course if you messed up on any of the above steps, or if your program crashed and damaged the loader program, you had to start all over from the beginning.
From Arnold Reinhold's Computer History page (http://www.hayom.com/computer-history.html), with permission.