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cbmhardware
Account closed
Registered: Aug 2003
Posts: 19 |
AVR C64-Copro ?
Something first : my English is rusty . :/
I'm just writing a few lines for a first website of the project for the next .... years. ;0)
What did you think about this ? :
The goal of this project is to build an external CPU running for the C64. The development will show the final clocking of the used Atmel AVR. An easier way may be using the C64 dotclock running at 7,88 Mhz.
The Mega32 will listen to the I/O-Port of the C64 Cartridge-Port. If the signal is switched to low, the latched Mega32 will set DMA to low and take over the address-/datalines.
Now the C64 is under control of the VIC and external AVR. The Atmel will listen to BA and R/W to get the right moment to get a grip into the C64-memory.
The Mega32 contains 32kB Flash-Memory. There is enough space for the firmware and many routines for advanced C64-calculations.
There are two ways to transfer the right init for running the external calculations :
1. We store a signature on a fixed place in the C64 memory
2. We store a signature somewhere in the C64 memory and the AVR scans for it.
For example : $C,$O,$A,$V,$R,$routine,$datastart (hi,lo),$dataend (hi,lo),$data_target (hi,lo)
$C,$O,$A,$V,$R,$01,$10,$00,$20,$00,$10,$00
The Mega will get 4kB data from $1000 - $2000 into the own SRAM (64kB bank, take a look at the schematic) and will use calculation-routine $01. The resulting datas will be transfered to C64-Memory $1000 and up.
It may be useful for several applications : 3D-Graphics, Cruncher or doing something weird with bigger datablocks, the C64 can't handle in the needed time.
Hopefully I will be able to create a first prototype within this year.
http://www.cbmhardware.de/avrcopro/c64copro.gif
Michael
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Mace
Registered: May 2002
Posts: 1799 |
Somewhat like the SuperCPU?
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Raf
Registered: Nov 2003
Posts: 343 |
nice that someone catched that idea. in the past I also thought about something like this , but that was only dreaming as I probably don't have enough knowledge and moreover I don't have funds/time to spend on such project.
abyway I about actual coprocessor working in parallel with 6510/8502 rather that replacement (as far as I read - your project seem to be CPU replacemnt like SCPU as Mace mentioned)
www.vulture.c64.org |
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cbmhardware
Account closed
Registered: Aug 2003
Posts: 19 |
It is not a replacement for the S-CPU. The WDC65816 is 6502-compatible.
An AVR with RISC-architecture can only operate with the same data and (many) fixed routines. But this in a very fast way and for low money. Some ttl-logic, misc controllers, some diodes etc., Atmel Mega32 ... something about 20 Euro. Including a fast serial interface (115200bps) with own 64kB RAM-bank. |
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Kenho
Account closed
Registered: Jan 2003
Posts: 26 |
Hi, nice project but i for one think it is a bit strange not to use a 6502 compatible processor like the scpu. Infact making a new scpu which is compatible with the old one would be really good. Just making some improvements to it and so forth. Alot of people want a scpu i think... |
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Raf
Registered: Nov 2003
Posts: 343 |
atmega is much faster than 6502 so clocked doubled dotclock or so it should be able to emulate 65816 at full speed , problem here might be sync ;-)
and I didn't mean your project is replacement for SCPU , rather replacement for 6510/8502 built into C64.
www.vulture.c64.org |
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Oswald
Registered: Apr 2002
Posts: 5086 |
it should be foremost 6510 compatible, and then it might run in native mode too.
the problem with such HW projects is that there is no 'market' for them. the stock HW will be the default forever.
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Raf
Registered: Nov 2003
Posts: 343 |
@Oswald: True , and due to this I only wait for a 1541 electronics-hardware-level-compatible clone using different media to be affordable :)
mmc64 or ide64 amd such aren't replacements for 1541 due to huge amount of software runnable only with 1541, so a hardware 1541 emulator emulating CPU, 2x 6522 and rom/ram like 1541-ulitmate need to be made and spread :)
sorry for offtopic ;-)
www.vulture.c64.org |
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Mace
Registered: May 2002
Posts: 1799 |
Quoting RafI only wait for a 1541 electronics-hardware-level-compatible clone using different media to be affordable
There are currently two promising projects in development, so there's quite a good chance your dreams will come true. |
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insane
Registered: Nov 2006
Posts: 10 |
The Adlib/OPL3 scene is developing an external OPL3 USB-module, which has an eZ80 @ 50MHZ onboard. The eZ80 on the board has a 25pin DB25 port & 2 9pin joystick ports which can be used to interface the board with other computers and to use the eZ80 as coprocessor. |
