Repairing and modifying classic computer systems is a enjoyable solution to be taught extra about pc engineering with out having to cope with the large complexities of recent programs. Most fanatics contemplate the period of recent computing to have begun within the Nineteen Seventies with the introduction of microprocessors. Whereas these early computer systems are fairly completely different from the highly effective machines of as we speak, in case you squint, you may see a really related structure. There’s the CPU on the heart of the system, reminiscence chips, a video chip, I/O gadgets, and so forth.
However computing didn’t start with the introduction of the primary microprocessor or built-in circuit. The historical past of computer systems from earlier than that point is decidedly stranger to the trendy eye, full of electromechanical beasts that whirred and clicked their manner by calculations, and alien-looking reminiscence banks. If one desires to actually perceive how computer systems work and the way we acquired to the place we’re as we speak, this historical past shouldn’t be ignored.
A driving circuit for an array of magnetic cores (📷: HX2003)
A Singaporean {hardware} hacker that goes by the deal with HX2003 simply accomplished an fascinating undertaking that digs into the distant previous of computing historical past. The result’s a 512-bit magnetic core reminiscence system that operates at a no-so-blistering pace of 200 kHz. For these unfamiliar with magnetic core reminiscence, it was a well-liked expertise within the Nineteen Fifties by the early Nineteen Seventies. It consists of rings of a tough magnetic materials which can be magnetized in a specific course by an electrical present. The course of the magnetic subject in a hoop might be learn and interpreted as a zero or a one, permitting it to behave as one little bit of reminiscence.
HX2003’s design is structured as two 16×16 core reminiscence matrices, with two bits saved per addressable phrase. Writing to the magnetic cores is completed by utilizing coordinated present pulses by a grid of wires that connect with them. Studying the state of a core is completed with sense wires. These wires decide up tiny voltage adjustments when a core switches state.
To enhance accuracy and permit for scaling, HX2003 carried out a coincident present scheme, utilizing X and Y drive wires to pick out particular cores with mixed currents. A intelligent reuse of the sense wire as an inhibit line throughout writes permits a number of core teams to share driver strains with out undesirable interference, which is important for increasing reminiscence dimension whereas avoiding unintended bit flips.
The sense wire was threaded in numerous methods to search out the most suitable choice (📷: HX2003)
An RP2040 microcontroller generates the exact waveforms wanted for management. It additionally performed a task within the system’s testing, which included picture writing and traditional reminiscence diagnostic routines. These assessments confirmed steady efficiency over many gigabytes of information with no single error.
That is fairly an concerned undertaking, so anybody that’s serious about recreating it has to actually need it. If you’re a kind of folks and don’t thoughts placing within the effort to get your palms on some magnetic core reminiscence, HX2003 has written up a reasonably intensive information that may assist you alongside the way in which.
