compatible to the original PET, rather than branching off
with new incompatible systems.
So, my “ColourPET” project was born. I say “colour”
because pictures I’ve seen of one color prototype spelled
it this way, which makes sense since Commodore started
as a Canadian company, with headquarters less than 30
minutes away from where I sit.
I decided to go “old school” and use only standard
parts that were available back then. Later on, I could apply
what I learned to more advanced projects, perhaps using
CPLDs (complex programmable logic devices) or FPGAs
(field programmable gate arrays). Luckily, many early
vintage computers are quite hackable and the PET is no
exception. I started looking at the schematics (Figure 1)
and learning all I could about the hardware, as well as the
firmware. It turns out that adding color to the PET is not as
By Steve J. Gray
September 2015 45
FIGURE 1. The video
section of the PET
schematics.
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