Talk:Macintosh IIsi
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Untitled[edit]
"that one could speed up video considerably if one set the disk cache size large enough to force the computer to draw video RAM from faster RAM installed in the SIMM banks"
Video RAM was always in the lower RAM bank (built-in RAM). The video logic never was able to use the upper RAM bank (the SIMM slot). The speed up came from leaving the video logic alone in it's RAM only with the disk cache and force everything else to the upper RAM bank.
"To cut costs, the IIsi's video shared the main system memory, which also had the effect of slowing down video considerably"
The si had the same chip set (besides the swim chip) as the ci only running at 20MHz instead of 25MHz. Video logic and CPU were using the RAM interleaved and the timing didn't work correctly on 20MHz hurting performance in colour mode a lot (not in b&w mode as timing was fast enough for the less memory needed). Bringing the system back to 25MHz solved the problem. — Preceding unsigned comment added by 84.165.217.15 (talk) 19:37, 2 November 2011 (UTC)