Nel nostro viaggio attraverso il tempo, ci accompagna Davide Calvi dell'Associazione RetroEdicola Videoludica, meglio conosciuto come Dr. Fix, che ci racconta dettagli unici e aneddoti sul Cosmac ELF.
The computer that Davide Dr. Fix showed us is a replica of the Cosmac ELF, which he made himself.
The history of the Cosmac ELF and Joseph A. Weisbecker
The Cosmac ELF was conceived in 1976 by Joseph A. Weisbecker, a visionary engineer working for RCA. Weisbecker designed this microcomputer as an educational and accessible medium, publishing it in the journal Popular Electronics. The simplicity of the design allowed enthusiasts to build it themselves, using readily available components.
Il cuore del computer era il microprocessore RCA CDP1802 COSMAC, uno dei primi realizzati in tecnologia CMOS. Questo microprocessore aveva caratteristiche eccezionali per l'epoca: basso consumo energetico, un bus a 8 bit bidirezionale, un'architettura semplice ma efficace e molto altro.
Non a caso, l'RCA 1802 venne successivamente impiegato in alcune missioni spaziali della NASA, grazie ad una versione realizzata in silicio su zaffiro (Silicon On Sapphire).
COSMAC è l'acronimo di COmplementary Symmetry Monolithic Array Computer.
Technical characteristics of the Cosmac ELF
One of the most fascinating aspects of the Cosmac ELF was its minimal structure, which allowed users to understand how a computer works on a deeper level. Here are its main features:
- RCA 1802 processor (also COSMAC 1802): an 8-bit microprocessor, in CMOS technology, innovative for its resistance and reliability.
- 256 bytes of static RAM: an extremely small amount by today's standards, but enough for the educational purposes of the project.
- Manual input: This was done via switches to enter data in binary code.
- Visual output: used LEDs and two numeric displays to show the data entered and the results of the operations.
- Expandability: Thanks to additional modules, it was possible to add features such as video output, made possible by the CDP 1861 chip.
The architecture of the Cosmac ELF was deliberately spartan, but this simplicity made it perfect for those who wanted to learn the basics of programming and hardware.
An educational and revolutionary project
The Cosmac ELF represented a revolutionary idea for 1976. At a time when computers were only accessible to large companies or universities, Weisbecker envisioned a platform that anyone could build in their own home. This "do-it-yourself" approach turned the computer into a learning tool.
Dr. Fix points out how ELF has paved the way for generations of enthusiasts and engineers.
Modern replicas of the Cosmac ELF
In recent years, interest in vintage computers has led to the creation of replicas of the Cosmac ELF, which faithfully reproduce the original experience, but with some modern improvements. During the interview, Dr. Fix showed us and described his reply.
L'uscita video era resa possibile dal chip CDP 1861. Nella replica del Dr. Fix viene emulato con chip moderni, in quanto il chip originale è di difficile reperibilità ai giorni d’oggi.
An interesting aspect of the replica of Dr. Fix's Cosmac ELF is the ability to load programs automatically, without manually entering all the binary codes via micro switches.
This balance between past and present makes replicas perfect for both nostalgic people and those who want a little more convenience and speed in data entry.
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