Re: Apple II Bus Timing

[Patrick Schaefer <patrick.schaefer@topmail.de>]

"Matthew T. Russotto" schrieb:

> }The 6502 itself generates a second phi1 singal that is the complement of
> }its phi2, but this signal is not used.
> 
> It's used in the original Apple II and II+.

Ok, it is used by the OR gate 74LS32 at position C14 to control the 8T28
data bus transceivers.

However, the 6502's phi1 is NOT available at the expansion connector and
is NOT identical with Apple's phi1 generated by pin6 (/Q3) of the 74S175
at position B1. Apple's phi1 is just a complement of the phi0 signal
(pin7 of B1, output Q3). It was a bad idea to choose the same name for
both signals.


Patrick