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, SimCoupé 0.81a and ASCD 0.90 WIP 1. I get very different results from yours for both SimCoupé _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?) --- SimCoupé 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) SimCoupé 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) SimCoupé 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
