On Mon, Jan 25, 1999 at 12:42:31PM -0000, David Laundon wrote: > At the moment I'm working on the interrupt routines that drive the MIDI > output, so that when a MIDI interrupt occurs at the same time as a FRAME or > LINE interrupt it doesn't get missed. This has been made more difficult by > the fact that the MIDI interrupt signal only seems to last about half the > length of time as the others do (is this normal, or just my machine?)!
I don't think that's true, but anyway the MIDI interrupts are not essential, and their usefulness is somewhat reduced if you have to handle other kinds of interrupts going on at the same time. Unless your program needs to multitask I would ignore the MIDI output interrupt entirely and just code a busy loop before each output. There was a discussion of this last year (1998-06b, archive fans) in which I discovered the correct way to use the MIDI input interrupt, and posted the following pseudo-code for outputting a byte. putbyte: wait until in(248)&2 = 0 then output to port 253 imc
