Back in the early days of computing when only immense, big-iron computers roamed the earth, Stanley Frankel created the revolutionary LGP-30 desk computer. Back when the sale of one, two, or maybe three units per computer design was the norm, LibraScope built and shipped more than 500 LGP-30s from 1956 through the early 1960s. It proved to be a very durable design for the time. This tiny titan used only 113 vacuum tubes and 1450 newfangled germanium diodes (from the discard pile at Hughes Aircraft) to create a working computer. The LGP-30’s main memory and even its three 32-bit CPU registers were stored on its magnetic rotating-drum memory.
This ad for Stan Frankel’s LGP-30 personal computer appeared in the Proceedings of the IRE in April, 1959.
The LGP-30 was a significant milestone in computer history. It was the first computer to be used as a process-control machine due to its “low” $27,000 cost. John Kemeny and Thomas Kurtz at Dartmouth College used an LGP-30 during the early 1960s to develop several simplified programming languages designed for undergraduate study: DARSIMCO (Dartmouth Simplified Code), DART, ALGOL 30, SCALP (Self-Contained ALGOL Processor), and DOPE (Dartmouth Oversimplified Programming Experiment). They called the successor to these languages the Beginner’s All-purpose Symbolic Instruction Code (BASIC) but by the time they developed BASIC, they’d graduated to General Electric GE-225 and Datanet-30 computers.
Now, Jürgen Müller has developed a timing-faithful miniature replica of the LGP-30 called the LittleGP-30. It’s based on a Xilinx Spartan-6 LX9 FPGA, which recreates the LGP-30’s CPU and its rotating magnetic drum, reads the user controls, and drives the displays.
Jürgen Müller’s LittleGP-30 FPGa-based miniature replica of the 1950’s-era LGP-30 computer
You might well be expecting to see a big panel of blinking lights, as was common for computers of that era. However, the original LGP-30 used lighted pushbuttons to show the machine’s operational status and the internal machine state appeared on the front panel on an oscilloscope display. Müller has recreated the lighted pushbuttons using LED-backlit tactile switches and an LCD recreates the oscilloscope display. The 3-board LittleGP-30 uses a low-cost Numato MIMAS FPGA board based on a Spartan-6 LX9 FPGA. A custom control/display board with the LittleGP-30’s switches, LCD, a rotary encoder, and an HDMI port for displaying the entire contents of the machine’s emulated drum memory plugs into the Numato MIMAS board. A third circuit board on the top serves as a rather realistic reproduction of the LGP-30’s front panel—in miniature of course. Although it’s not currently a kit, Müller has posted a 42-page LittleGP-30 manual online.