DrZ80

[quzar]

Got a question about this thinger. Anybody have a ballpark figure of the ratio of emulated:actual clocks? For instance, does it take 10 or 50mhz to emulate a 4mhz z80? GBA, NDS, or GP2X. preferably numbers of it running on an arm7?

[BlueCrab]

Planning on running Genesis sound emulation on the AICA eh?

On question though, I dunno at all.

[quzar]

Not really planning, and not really genesis. Imma try to find something I can write up to see what can be done on the aica. I have a feeling it hasn't been tried because of the "it's impossible" sentiment. Most of the argument I've seen against it is that it's impossible because of the extremely slow data rate between the aica and the rest of the system. If *all* the sound emulation were run inside the aica, then the only data needed to be sent to the aica would be sound commands(basically not a whole lot). I also think people underestimate what a 24mhz (and we can overclock it) arm can do. The gba's arm runs slower and it's only advantage (that I know of) is that it has thumb mode.

[Christuserloeser]

I have a feeling it hasn't been tried because of the "it's impossible" sentiment.

I thought the same. :)


I also think people underestimate what a 24mhz (and we can overclock it) arm can do. The gba's arm runs slower and it's only advantage (that I know of) is that it has thumb mode.

Yup. Btw, did you notice my thoughts I've posted at the DCEmulation Forums (http://dcemulation.com/phpBB/viewtopic.php?t=83409&postdays=0&postorder=asc&start=260) ?


Now I wonder if the Dreamcast's ARM7 could be used for anything ?

I know it only has 24Mhz/32bit but what if there would be a Z80 emu in ARM assembly ? or what if CZ80 would be compiled for running on the ARM7 ? I remember reading that the Z80 could be underclocked to the lowest possible speed and still would work:



I wonder if FAZE (once it's finished) could provide at least a little speed boost...

Maybe, but it won't be very much.

If you remember back when the original GP/DC was released, it had an option to adjust the Z80 clock. Changing the clock to the lowest possible speed sped things up significantly. That option is no longer there, because it makes no noticeable difference anymore.

So maybe when CZ80 would be compiled for the ARM7, and then underclocked - would that... work ?


Then I posted some links. I don't know if the ones I posted are any faster or more accurate than DrZ80.


At Jeff Frohwein's GBA dev site, I found some ARM compilers:
http://www.devrs.com/gba/software.php


Even two ARM Z80 emulators:


2002/06/30 - Peter's Z80 Emulator (http://www.peter-teichmann.de/asoft.html) - Posted by: Jeff Frohwein
This z80 core emulator was written to run on a StrongARM processor but it might can be adapted to the GBA's ARM7 processor. Here are some other CPU cores for ARM processors:
Foon (http://foon.pocketheaven.com/) - z80 core

[quzar]

Since this has never been done before I am first looking into how it would be done at all (logistically). I am 100% sure it is technically possible, I simply don't know how to go about working it out in code.

I've been writing an emulator from scratch to test out something like this (not z80, not genesis, or anything. something small).

In the next year or so we'll see what happens.

[HardHat]

Well, I know that the Coleco Adam emulator AdamEm works fairly well on a 33 MHz 386 (the Adam is a 3.77MHz Z80-A based system), but to get full speed you'd need at 386-66. On the otherhand, I'd bet that the bottle neck was also emulating the video display. Considering the power of the ARM7 instruction set, I think that 24MHz ARM7 assembly implementation has potiential. Especially if the rest of the hardware were emulated on another CPU. Have fun.