Zilog Made a Clone!

A project log for uPD7220 Retro Graphics Card (and VGA hack)

Making an 80s GDC run for the first time in decades, and my first real hack on

Dylan BrophyDylan Brophy 04/18/2019 at 01:470 Comments

I bought this chip off of Ebay.  It seems that Zilog created a uPD7220 clone - and it works!  These chips seem to be rather rare and information on them is scarce.  I did manage to deduce that there were two variants of chips:  one operating at 6Mhz, and one at 8Mhz.  I got the 8Mhz one and tried doubling my pixel clock to 16Mhz (the GDC uses a halved clock).  That worked too, and that allowed me to make a more stable video signal.  I had a problem with the 8Mhz pixel clock where there was not time to output a valid video signal.  Now I can output more pixels than I have VRAM for.

The chip is also a super pretty Zilog gem <3