Repairing and modifying classic computer systems is a enjoyable method to be taught extra about pc engineering with out having to cope with the large complexities of contemporary programs. Most fanatics think about the period of contemporary computing to have begun within the Seventies with the introduction of microprocessors. Whereas these early computer systems are fairly completely different from the highly effective machines of right now, in the event you squint, you’ll be able to see a really related structure. There may be the CPU on the heart of the system, reminiscence chips, a video chip, I/O units, 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 fashionable eye, stuffed with electromechanical beasts that whirred and clicked their approach via calculations, and alien-looking reminiscence banks. If one needs to actually perceive how computer systems work and the way we acquired to the place we’re right now, 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 challenge 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 velocity of 200 kHz. For these unfamiliar with magnetic core reminiscence, it was a well-liked know-how within the Nineteen Fifties via the early Seventies. It consists of rings of a tough magnetic materials which might 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 finished through the use of coordinated present pulses via a grid of wires that hook up with them. Studying the state of a core is finished 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 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 several 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 basic reminiscence diagnostic routines. These exams confirmed steady efficiency over many gigabytes of information with no single error.
That is fairly an concerned challenge, so anybody that’s inquisitive about recreating it has to actually need it. In case you are a kind of folks and don’t thoughts placing within the effort to get your fingers on some magnetic core reminiscence, HX2003 has written up a reasonably in depth information that may allow you to alongside the best way.