Other clocks

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The Acorn (type 1) clock box The Acorn clockbox type 1 (grey and light grey case with one socket) is a symmetrical clock. The MARK and SPACE times are always identical. Because of this, you cannot adequately set the clock to match your network; as you really need the shortest MARK possible with the longest SPACE (as this is when data is transmitted). You are advised to seek out a better clock box. There are fourteen links inside this clock. You select the clock rate by making the link alongside the speed at which you want your network to operate. Values given are in hertz. 614K o o 307K o o 153K o o 460K o o 76K o o 230K o-o < This is the default setting, 230kHz 38K o o (approx. 1µs MARK, 1µs SPACE) 115K o o 12K o o 8613 o o 19K o o 7035 o o 9600 o o 4800 o o   The Interclock If I recall correctly, this is a network card (Master/Archie style) which has clock generation circuitry on it. I think it suffers from low clock output power. I would imagine that this card was most likely designed to piggyback two machines to each other with the minimum of complications.   BBC micro Didn't some versions of the BBC micro (issue 3 board?) have provision for a clock to be fitted if required?