On 6/28/2014 12:12 PM, Gerrit Heitsch wrote: > On 06/27/2014 02:15 AM, Kajtár Zsolt wrote: >> -----BEGIN PGP SIGNED MESSAGE----- >> Hash: SHA1 >> >>> As before, I still don't have a clear picture of how exactly is this >>> supposed to work. Either this or the (presumably simpler) approach with >>> an EPROM and a 4040. I think I am not alone in this and that is one of >>> the reasons nobody (including myself) haven't done it yet. >> >> It works the same way as the EPROW+counter approach. Except that the >> external >> 6502 is the "counter" for addressing the EPROM. Which has the benefit of >> inserting dummy fetches automatically to the bus when needed. This >> way you >> could use any assembler/monitor to produce the code for the EPROM, >> without >> tricks. And this 6502 could be used for the communication with the >> 6500/1 to >> dump it's content too. > > An idea worth thinking about. You still have that clock divided by 2 > problem though and have to make sure somehow that the two 6502 are not > off by half a cycle. > > Gerrit > > > > Message was sent through the cbm-hackers mailing list I have sitting on the bench, a 6500/1 I pulled from a 1520 here, and a ATMEGA644P. Not sure I have a 20MHz crystal, but i have a 16MHz one. I am happy to whip up some code to try here, but any help would be appreciated. I'll set up a 250kHz square wave on one of the OC outputs. global var will track first or second cycle. one pin will set RESET to 10V or 5V. Still working out how to create the voltage difference at the RESET pin. I can tie RESET to 5V through a IO pin and a diode, and then put a transistor on 10V PSU output, but then that will be 9.3V. I am not sure I have a 10.7V PSU output. PORTC will be tied to a port on the AVR PORTB will be tied to a different port. What I'd like help with is a sequence of bytes (including any dummy bytes needed) to sending to portC once I release RESET and drive it to 10V. At first, I'd like to start with something that will accomplish something on portb as quickly/simply as possible, like driving all pins to 1 or 0 or something. I figured maybe I could tweak things until it works, and then I might be able to do something more complex. Jim -- Jim Brain brain@jbrain.com www.jbrain.com Message was sent through the cbm-hackers mailing listReceived on 2014-06-29 08:00:03
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