Re: Commodore joystick ports

From: Greg King (
Date: 2004-11-27 05:46:02

From: Jim Brain; on Date: November 03, 2004, at 01:46 PM -0500
> I wonder why they felt the need to discharge the SID's caps. for
> 256 cycles.  It seems like they would lose charge after just a few.

Probably, because it is convenient -- the circuit can be simpler.  A
nine-bit counter can control everything:

* The ninth-bit can control the discharge transistors directly; and, it can
reset the comparators.

* The lower eight bits can be the up-counter -- each voltage comparator can
latch the current value of those bits into its POT output-register when its
capacitor rises to the trigger voltage.

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