[vcf-midatlantic] examples of non-crystal based clocks in digital computing?

Systems Glitch systems.glitch at gmail.com
Sun Mar 13 10:28:04 EDT 2016

> The Scelbi 8H and 8B do not use crystals for system clocks which is why they need military spec parts in the timing circuits or they drift as the temperature of the system changes.  

Many early hobbyist computers didn't -- it was common with 8008 and 6502 homebrew designs to just use a RC oscillator. Several of Ohio Scientific's 6502-based systems used RC oscillators (the 400 board used a 555 for the more precise task of ACIA clock!), and the John Bell Engineering 6502 single-board embedded computer also used a RC oscillator, with a note on adding a crystal clock if you need stable timing.

The Intel 8085 can use a RC (or LC) oscillator, but I don't think I've ever seen an example of that, probably because crystals had become cheap enough for hobbyists and even cost-reduced products by that point.


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