Pentagon 48 или GRM1 начало INTа

[Shockwav3]

Currently experimenting with the circuit proposed by LEN2PEN2.TXT (Output of DD6.3 [Pin8] through 1.2K resistor -> 6.8n capacitor tied to ground + inverter -> !INT on Z80) I'm getting something extremely close to a correct timing for the Rage endpart (can't see any offset while it's moving and the "paper wobble" at the beginning actually looked correct, with the screen standing it's 1px) - only problem, this only happens on every second or third reset.
I also did replace D40 with a 74ALS174 (because I managed to break off a pin off my 74LS174).


This is how the circuit is currently modified:


EDIT: Looks like I'm not quite done yet ... on a second testrun the border was 1 pixel late (instead of early), TestINT no longer reports a value and BorderCreate simply crashes.