Although the functionatlity of the ACID chip is known. The timings of the signals coming from the computer is still unknown (reverse-engineering was done on a ACID chip, without owning a CPC+/GX4000).
* CLK is known to be 4MHz, and SIN is known to be updated on falling edge of CLK, as seen on [[Media:ACID-SIN.jpg|this picture]].* Judging from the ACID chip, /CCLR is checked on falling edge of CLK. However, juding from [[Media:ACID-CCLR.png| this picture]], /CCLR is ''changing'' on falling edge of CLK. If this is true (the picture resolution isn't perfect), then it's unclear how the ACID can interprete /CCLR in a stable way while it's changing. Possibly, it can't do that at all (ie. it might act unstable, and the CPC+ might need to retry sending /CCLR several times).
** A picture showing CLK and /CCLR without ACID connected (at better resolution) would help!
** A picture showing CLK and /CCLR with ACID connected would be nice, too (trigerred on the LAST /CCLR coming from the CPC).