Thanks Marcel! >I'm no hardware guy, but I'm pretty sure the ULA locks ALL internal >memory during screen refresh, i.e. depending on model (EU/US) 50 or 60 >times per second. The CPU cannot access anything at all during these >times.
OK, I will measure read/write time in the vram anyway. ULA should somehow share bus with CPU, it should not lock memory the whole TV frame refresh. >Some memory expansions like the Trump Card are not as limited, you >do not get any delays accessing the extended RAM there. On Amiga there is Chip RAM and Fast RAM. Chip RAM is shared between CPU and all coprocessors. In chip RAM is program running slower, because coprocessors has priority over CPU. Fast RAM is used only for CPU, therefore program runs faster here. I think this is case of Trump (and Sandy?). Extended memory is Fast and base lower 128k of RAM (??? or 64k of VRAMs only?) is Chip (slow), because it's shared with ULA. The same exists on ZX Spectrum, but it's well documented/implemented feature of ZX hardware. I think Sinclair didn't reinvent the wheel and used the same principle on QL. >> Is there any emulator emulating that feature? >No emulator comes anywhere near a cycle-exact emulation. OK. Thanks. ------------------------------------------ www.icq.atlas.cz/ _______________________________________________ QL-Users Mailing List http://www.q-v-d.demon.co.uk/smsqe.htm
