From: Jim Brain (brain_at_jbrain.com)
Date: 2004-05-25 23:50:08
firstname.lastname@example.org wrote: >Hi Jim, > > > >>Why send UNTALK over the wire? Can;t the peripheral just assume that >>when it completes sending data? I figure the answer has something to do >>with FILE reads, but I have not gotten there. >> >> > >In most cases the peripheral does know when it finishes, afterall it sends >an EOI (tells the C64 the next byte is the last). In this case the UNTALK is >almost a confirmation. More importantly however, imagine this. You are >"loading" a program, then press RUN/STOP. The C64 has to tell the drive to >stop sending data. It signals ATN, with an UNTALK. > >- Nick > > > That's fine. My code switches back into IDLE state when ATN goes low. I just wanted to make sure that switching to IEC_CMD_STATE_IDLE after a successful data transfer would not cause issues. Now, I am stumped for a good RS-232 protocol to support data transfers. Obviously, the serial port doesn;t really have an ATN line (I gave some thought ot using DTR, but that won't work on all environments, cannot be read by all OS's (without IOCTLs and such)), so I need to way to deliniate commands, data, and EOI on the serial port... (Yes, I could write a higher level set of code in the controller, and I will, but I assume some people will want essentially RAW data.... I came up with this, but it's just a stab at something, comments are appreciated: (all data in hex) FF is "command" char. If it appears in data stream, replace with FF FE FF 00 reset interface FF 01 X listen as device X FF 02 X unlisten as device X FF 03 X <data> configure virtual device X FF 04 end of cmd/sync FF 10 reset IEC bus FF 11 IEC CMD FF 12 IEC Data FF 13 IEC EOI FF 14 X Turn ON error LED (if just one device, X is unimportant, just discard it.) FF 15 X Turn OFF error LED I have some other higher level commands, but wondered what folks thought of these. I tried to decipher Marko's format, but I can;t figure it out... Jim -- Jim Brain, Brain Innovations email@example.com http://www.jbrain.com Dabbling in WWW, Embedded Systems, Old CBM computers, and Good Times! Message was sent through the cbm-hackers mailing list
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