Re: C64 music player source

From: Richard Atkinson (
Date: 2000-02-01 01:09:35

Thanks for all your help with players - I now have more than enough to
test my protocol. Initially I am using it to sync two machines together
playing the same sid tune. When I have the data transfers working, I can
even use it to issue commands from the master C64 to the slave C64. I've
decided that the master will be the only machine that uses the disk drive
- one of the commands tells the slave to go to sleep while the bus is used
for Commodore's normal disk drive routines. When the data is loaded, the
master then has to transfer it to the slave using 'load data' transfer
commands. The format is a one byte command word with variable length data
fields after that depending on the command.

All this means that the slave has to be able to wake up at some point
after all disk transfers have finished, and I am also using the 'slave
wakeup' protocol to establish master / slave identification on first
running the program. Both machines load the same program, the difference
being that the first machine executes the 'wakeup slave' method and gets
no response (being the only machine on the bus) so it assumes the role of
slave and goes to sleep. Then the master computer is added to the bus, the
program loaded and it does get a reply from the slave device using the
'wakeup slave' protocol, hence it assumes the role of master.

What I need to know is how to send out a 'wakeup slave' message that won't
be confused for standard serial bus data transfers. I am only using CLK
and DATA in all of these protocols (since C64s can't read ATN), so I think
the drive will ignore them, and I think pulling both CLK and DATA low for
a long time will not be confused for drive traffic, but how long is
necessary? After the slave has been woken up, the two machines talk to
each other using my own protocol and whenever it is necessary to perform
drive transfers, the master sends the slave back to sleep again. What
would be long enough to not be confused with disk drive signals?


This message was sent through the cbm-hackers mailing list.
To unsubscribe: echo unsubscribe | mail

Archive generated by hypermail 2.1.1.