[comp.music] HELP! My Mac IIfx modem port can't be un-MIDI'ed!

midkiff@portia.Stanford.EDU (Neil Midkiff) (01/13/91)

I have a problem with the modem port on my Mac IIfx.  After running
the MIDI sequencer program EZVision from Opcode Systems, the port
appears to be "damaged" for normal data-modem use.  Specifically, I
can send ASCII to the modem (proved by the fact that it will accept
Hayes dialing commands, etc.) but no ASCII data comes back from the
modem (no command echoes or OK's).
The modem itself is working, since I can use it perfectly well from
the printer port, when I set the communications program (Quick Link
II) to use the printer port.

The modem port works for both input and output in MIDI mode using
Opcode's MIDI Translator interface with my keyboard and tone
generator.

The software seems to work "as advertised"...that is, upon exiting
EZVision, the ports are freed up for other programs now.
	[This was not initially the case; at first, EZVision had to be
	["helped" by manually disabling MIDI for the serial port
	[before quitting the program.  Then I found a copy of Apple's 
	[MIDI Manager (on the Lime distribution from U of Illinois)
	[and installing that fixed the problem.  Alternatively,
	[Opcode's MIDI Init will also make the port-freeing automatic.

However, nothing I can do (including zapping the PRAM) seems to fix
the one-way data modem problem.  Can anyone explain to me whether some
strange sort of hardware defect can allow MIDI to work on input and
output but RS-422 ASCII only on output?

Additional info: System 6.0.5 (recently reinstalled from distribution
disks), IIfx Serial Switch cdev set to "Compatible" mode.

Does anyone know where I can find documentation for the MIDI Manager?

Immense, heartfelt thanks to anyone who can provide any help at all.
I can still function by using the modem from the printer port, but
that involves unplugging the printer and disabling AppleTalk every
time I want to log in to the mainframe I'm using now, and reversing
the process for printing.  I didn't expect to have to devote one
serial port permanently to MIDI.

-Neil

dbell@cup.portal.com (David J Bell) (01/13/91)

Neil:

>I have a problem with the modem port on my Mac IIfx.  After running
>the MIDI sequencer program EZVision from Opcode Systems, the port
>appears to be "damaged" for normal data-modem use.  Specifically, I
>can send ASCII to the modem (proved by the fact that it will accept
>Hayes dialing commands, etc.) but no ASCII data comes back from the
>modem (no command echoes or OK's).
>The modem itself is working, since I can use it perfectly well from
>the printer port, when I set the communications program (Quick Link
>II) to use the printer port.

>The modem port works for both input and output in MIDI mode using
>Opcode's MIDI Translator interface with my keyboard and tone
>generator.

I'm not familiar with the interface you're using, nor with the
software, but this sounds an awful lot as if something (a still-
resident MIDI driver, for instance) is trapping received data
interrupts on the COM port. Properly behaved software should not
service interrupts from a device that it is not currently using,
but this type of error is not uncommon between different programs
co-residing in the O.S...

Maybe someone with more MAC MIDI experience can tell you more.

Dave