
More CGA CRTC Glitching: HD6845(R) vs. MC6845
We've seen how the MC6845 CRTC can produce unintended, 'phantom' vertical sync pulses if R7 is rewritten during active display time. How about the HD6845? Well, Hitachi's 6845 variant appears to be more sensitive, and will glitch in even more cases than its Motorola counterpart.