Repairing and modifying classic computer systems is a enjoyable method to study extra about laptop engineering with out having to cope with the large complexities of recent techniques. Most fanatics contemplate the period of recent 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 as we speak, for those who squint, you may see a really comparable structure. There’s the CPU on the middle 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 fashionable eye, crammed with electromechanical beasts that whirred and clicked their approach by way of 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 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 attention-grabbing venture 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 Fifties by way of the early Seventies. It consists of rings of a tough magnetic materials which might be magnetized in a selected path by an electrical present. The path of the magnetic discipline in a hoop will 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 way of a grid of wires that hook up with them. Studying the state of a core is completed with sense wires. These wires choose up tiny voltage adjustments when a core switches state.
To enhance accuracy and permit for scaling, HX2003 applied 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 critical for increasing reminiscence measurement whereas avoiding unintended bit flips.
The sense wire was threaded in numerous methods to seek out the best 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 and not using a single error.
That is fairly an concerned venture, so anybody that’s occupied with 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 arms on some magnetic core reminiscence, HX2003 has written up a reasonably in depth information that may enable you alongside the best way.
