Xref: utzoo comp.sys.mac.programmer:8739 comp.sys.mac:37303 rec.music.synth:8809 Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!cornell!uw-beaver!ubc-cs!alberta!calgary!amc-vlsi!green From: green (Brian Green) Newsgroups: comp.sys.mac.programmer,comp.sys.mac,rec.music.synth Subject: Mac SCC madness (Multifinder deranged?) Keywords: MIDI, Multifinder, Mac Message-ID: <832@amc-vlsi.UUCP> Date: 29 Aug 89 22:14:02 GMT Sender: news@amc-vlsi.UUCP Distribution: na Lines: 30 I have a Mac SE/30 for which I am (GASP!) writing my own SCC (serial controller) interrupt service routines so that I can develop some MIDI utilities (yes, yes, I know that there is a toolkit available...). So far, I have had great sucess intercepting, buffering, and re-transmitting the MIDI stream from my keyboard under FINDER, but when I run the application under MULTIFINDER, I am plagued by seemingly random losses of MIDI data, along with occasional total lock-ups of the Mac (requiring power down to reset). Can anybody suggest what I may be doing wrong? I have tried to follow the compatibility guidelines in Inside Macintosh I-V which include: - not using the user stack pointer in assembler routines - not changing interrupt status - not making assumptions about the location of the application or system heaps - not doing anything to the status register. I suspect that the problem has something to do with Multifinder periodically taking over for so long that a receiver overrun occurs. Any suggestions? Sorry to the rec.music.synth group if this posting doesn't belong there, but I have on occasion read some excellent technical discussions there. Please reply via e-mail and I will summarize to the net if responses warrant it. green@amc-vlsi.uucp (Brian Green)