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From: phil@sivax.UUCP
Newsgroups: net.micro.mac
Subject: Re: Configuring the SCC chip on the Mac
Message-ID: <257@sivax.UUCP>
Date: Thu, 5-Jun-86 13:12:18 EDT
Article-I.D.: sivax.257
Posted: Thu Jun  5 13:12:18 1986
Date-Received: Sat, 7-Jun-86 08:26:30 EDT
References: <676@ur-helheim.UUCP>
Distribution: net
Organization: System Industries, Milpitas, Ca
Lines: 37

> 
> Hi,
>     I'm engaged in some research in networking and I need to use the
> Mac as an experimental node. My problem is that I have to reconfigure
> the Zilog 8530 SCC chip that controls the printer and modem ports. Here
> are some questions I have, which I would appreciate answers to:
> 	1) How many SCC chips are there in the Mac? Does one chip
> 	handle the printer and modem ports AND the mouse?
> 
> 	2) Are the physical addresses of the various registers on the
> 	chip documented anywhere? Indeed, is there ANY documentation
> 	that will ease my task?!
> 
> 	3) If any of you have attempted/succeeded in programming the
> 	beast and know it's quirks, I'd be grateful for any
> 	information. IM doesn't seem to be much help, as this is
> 	pretty low level assembler stuff.

Yes, I have proigrammed the SCC chips,  we connect a CDROM drive to it at
700K baude external clock.  There is only 1 SCC 8530 chip.  Yes, the mouse
interrupts come in on the chip, causing lots of problems.   The stuff needed
to program the chip is documented in the SYSEQU.TXT file with the MDS system.

There are 2 or 3 equates that let you 'talk' directly to the chip,
ADATA,ACTL,BDATA,BCTL, SCCrd,SCCwrite,  No there is no real docs on how to do
it.  The only real quirk I found about the chip is the 2.2 microsecond wait
between commands sent to the chip.  It requires this delay, which I handle with
a   MOVE.L (SP),(SP)  instruction as a slow NOP.

Any other questions, send me mail

Phil Hunt

Calma!sivax!phil


>