How about using the '299 shift register as a base for an SPI interface?

http://www.ti.com/lit/ds/symlink/cd74hct299.pdf

Some extra logic would be required but I think it could be done.

This topic got me doing some archeology among old Eagle files from many years ago when I was toying around with the thought of a dedicated PS/2 keyboard interface. The idea I had was to use two shift registers to capture an entire byte from the keyboard including start, stop and parity bits. When ...

Mike, you are absolutely right. That's exactly the situation I was trying to describe. I believe this is true for many constructions and in most cases it's no problem. Nice trick mentioned by nyef. That's pretty cool!

Regards,
Daniel

Thank you for the kind words. I really like that way this interface turned out.

I may have to rephrase the part about the banding artifacts. It's not really an artifact and is coming from the fact that this is an asynchronous write-only interface and the CPU has no way of telling where the beam is ...

I just completed a very simple PAL video interface for my MC3 computer. The computer itself is not 6502 based but the video interface uses only standard components and may be of interest anyway.

http://www.waveguide.se/?article=bitmap ... -interface

Regards,
Daniel

Nice work!

I agree on the reset circuit. Add a capacitor to ground. A clean reset is important.

Take a look at my 6303 design to see how I solved it with an RC net and a buffer.
http://www.waveguide.se/?article=mc3-a- ... t-computer

Daniel