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Old 26 August 2018, 07:50   #211
Bruce Abbott
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Originally Posted by plasmab View Post
Remembering that RAM was the most expensive thing about the machine at the time
Yes, RAM was generally the most expensive part. Commodore originally wanted the A1000 to have only 128k on the motherboard, to keep costs down.

If my RAM is 150ns i basically try and design the circuits around it to be as close to that as possible.
But support chips also have propagation delays which need to be minimized. In 1983 the cheap high speed low power options we have today were not available, so faster chips were more expensive and drew a lot more power - requiring a more expensive power supply, better heat-sinking or fan cooling etc., all of which could raise the cost significantly.

And as timing approaches the minimum the design gets more critical, less tolerant of things like PCB layout and component variations, and generally harder to get right. Development costs go up, reliability goes down. Running at the ragged edge to get a little better performance might sound like a good idea, but would be a disaster if 1 in 100 machines randomly crashed or had visible glitches.
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