Agnus Internal Timing

Internal Clocks

There are two critical internal clocks used by Agnus/Alice, PH2 and PH1. These two clocks appear to be used almost exclusively. PH2 goes low approximately 15ns after CCK goes high and returns high approximately 30ns after CCKQ goes high. PH1 is an inverse of PH2 with another 15ns of padding and is a very narrow signal.

____                 _______________
    |_______________|               |_______   CCK (3.58MHz Color Clock)
____________                 _______________
            |_______________|                 CCKQ (3.58MHz Color Clock Quadrature)
______________________           ___________
                      |_________|              PH2 (85ns negative pulse)
                         _____
________________________|     |_____________   PH1 (55ns positive pulse)

These timings are based on average-case performance of HCMOS gates of the era and could be tighter on a cold system and slower on a very hot system. I would say these are +/-8ns, or about 7-23ns per gate.