Aley Keprt wrote:
> Yes, there are many bugs.
> I have a special test software which gives 4.8MHz speed on
> real Sam and 3.17 on SimCoupe.
> ASCD shows only 2.72MHz. Eh....
I did some tests last night using my real SAM, SimCoup� 0.81a and ASCD
0.90 WIP 1. I get very different results from yours for both SimCoup�
_and_ ASCD - were you using very old versions?
For anyone interested, the tests use a CPU speed measurement program
from issue 7 of the KAPSA disk magazine. The ROM and RAM values below
are the measured speeds (approx. in MHz) of some test code running in
ROM and RAM memory areas:
---
Real SAM:
MODE 1: ROM=5.986, RAM=4.428
MODE 2: ROM=5.988, RAM=4.883
MODE 3 and 4 (video on): ROM=5.988, RAM=4.883
MODE 3 and 4 (video off): ROM=5.988, RAM=5.561
I figure the slight difference in ROM speed for mode 1 must just be the
forced ASIC slow-down affecting the test code during it's time in RAM.
---
ASCD 0.90 WIP 1:
All modes and settings: ROM=3.104, RAM=3.104
ASCD doesn't implement any sort of contention for ROM/RAM/screen-off, so
the running speed never changes. It does surprise me that the measured
value is at least 50% out from real SAM values though. (Aley?)
---
SimCoup� 0.81a:
MODE 1: ROM=5.561, RAM=4.883
MODE 2: ROM=5.561, RAM=4.883
MODE 3 and 4 (video on): ROM=5.561, RAM=4.883
MODE 3 and 4 (video off): ROM=5.561, RAM=5.561
The contended and uncontended values for RAM are already perfect, which
shows Dave Laundon's per-access timing changes work well. There are two
_documented_ deficiencies that I believe will cover the other
differences:
1) SimCoup� doesn't currently implement unrounded ROM timings, so the
ROM is treated as uncontended RAM (making it ~0.4MHz slower than it
should be). This will be a bit nasty to implement, and probably won't
be done for a while yet.
2) SimCoup� also doesn't implement the forced slow-down used by the ASIC
in mode 1, to make the running speed closer to Spectrum speed. This is
something that I hope will be done soon, even if just to improve one
results above!
I'm not aware of any other timing problems at this time - certainly no
bugs, as was suggested...
---
Si
