Pseudonymous maker “P-Lab” has made a Zilog Z80-based single-board laptop with a distinction: it packs a simplified model of the kind of core-rope reminiscence that despatched NASA’s Apollo missions to the moon.
“It is a demonstration board to indicate the operation of the so-called ‘Woven-Wire Learn-Solely Reminiscence,'” P-Lab explains of the system, which performs its computation with a Zilog Z80 eight-bit processor and outputs to a pair of seven-segment shows. “This system is said to the well-known ‘Core Rope’ Learn-Solely reminiscence utilized by NASA in Apollo missions (and never solely) within the AGC (Apollo Steerage Laptop), however it’s easier.”
Magnetic-core reminiscence is, because the identify implies, reminiscence constructed utilizing magnetic cores woven onto wires that may learn and alter their polarity — storing information one-bit per magnetic core. Core rope reminiscence is a variant of this, simplified by the exclusion of any capability to jot down — with information being saved for later retrieval in the best way the magnetic cores are wired collectively, slightly than their magnetic polarity at any given time limit.
Probably the most well-known use of magnetic rope reminiscence as a strong read-only reminiscence is in NASA’s Mars area probes of the Nineteen Sixties and the Apollo Steerage Laptop, which took astronauts to the moon and again once more. It is this latter implementation that impressed P-Lab’s Z80-powered single-board laptop, although its reminiscence is easier nonetheless — simply 16 bytes of woven-wire core reminiscence.
The woven-wire reminiscence, seen to the highest of the single-board laptop, is programmed in the way it’s wired up. (📷: P-Lab)
“Functionally,” P-Lab explains, “the microprocessor reads and executes the beforehand woven code with wires passing out and in of the person cores. The sequences of 1s and 0s are nothing greater than the interpretation of this system supply code into binary. Particular person traces are activated by way of a 2N2222 transistor, which is pushed by the 4-to-16 decoder linked to the primary 4 bits of the Handle Bus. The design was made with scavenged materials, some selections are additionally a consequence of the structure chosen for the elements (e.g., the A/B route of the 74HC245 requiring an inverter).”
P-Lab has documented the mission on their GitHub Pages website, with extra info — and an indication of utilizing the system to calculate a Fibonacci sequence — out there within the video embedded above and on the P-Lab YouTube channel.