2 Oct
2007
2 Oct
'07
12:57 p.m.
If I remember right, the architecure of the ti chip
it used a pointer to ram as the internal registers. That would really
bog down on byte wide bus.
But then chips like the 9995 do very well on a 8-bit data bus. IMHO the
bigger problems with the 9900 implementation in the 99/4A were the external
scratch pad (made internal for the 9995) and the presence of GROMs,
requiring their own interpretation step and murderously slow serial access.
Compare this to a system like the Tomy Tutor, which has a 9995 on an 8-bit
bus too, but is significantly faster than the 99/4A despite being clocked
slightly slower (10.7MHz oscillator instead of the 99/4A's 12MHz one).
--
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Cameron Kaiser * Floodgap Systems * www.floodgap.com * ckaiser at floodgap.com
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