Dave Park wrote, on 19/Feb/11 17:31 | Feb19:
Could you educate us a little on how the 8049 (which is a standard Intel
microcontroller) gets its program? How is an 8749 different from an 8049?
Does it run the same program the 8049 runs but better, or a different
program provided by the *Hermes?
I've often thought of 8049 and 8749 as not interchangeable, but I don't
remember why. I vaguely recall the 8749 had more functions and internal
memory, and could clock faster than the 8049's 11MHz, but I do not trust my
memory on this. Will look it up later.
Anything you say may be taken and used to improve the wiki ;)
Laurence is the real guru here. He did an amazing job simply re-writing
the code for the *same* environment - the 8749 is identical in
operation, and is simply an eprom version.
Not only did he get the code working but he also made some improvements
to the sound. I almost said 'sound improvements' which is also true but
not the same thing (8-)#
The most important change though was to get serial input handshaking
working.
There was a chip sold for the Schoen keyboard to get rid of keybounce.
It certainly did that but killed the serial port!
I reminded him of this and literally at the 11th hour, added code to
stop keybounce, almost as an afterthought.
I hope the lurking(?) Laurence can add to this.
Tony
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