Path: utzoo!attcan!uunet!samsung!brutus.cs.uiuc.edu!apple!carl
From: carl@Apple.COM (Carl C. Hewitt)
Newsgroups: comp.sys.mac.hardware
Subject: Re: Apple Announces High Performance Products
Message-ID: <7338@goofy.Apple.COM>
Date: 21 Mar 90 22:08:05 GMT
References: <39637@apple.Apple.COM> <1990Mar20.161729.9549@chaos.cs.brandeis.edu> <7307@goofy.Apple.COM> <39692@apple.Apple.COM>
Organization: Apple Computer Inc., Cupertino, CA
Lines: 33

In article <39692@apple.Apple.COM> anderson@Apple.COM (Clark Anderson) writes:
>From: dwb@archer.apple.com (David W. Berry)
>>There are to IOP's, each is a modified 6502, including 32K of
>>memory.  One is attached to the serial chip and the other to ADB and
>>who knows what-all-else.  
>....
>Not exactly. One IOP (identified as a PIC on the motherboard,
>"Peripheral Interface Chip") controls the two serial ports, the
>other is dedicated to the floppy I/O. The ADB circuitry is
>essentially unchanged from the Mac II.
>                                            --clark
>
>-----------------------------------------------------------
>Clark Anderson                  InterNet:  anderson@apple.com
>CPU Engineering                 AppleLink: C.ANDERSON
>Apple Computer, Inc             BellNet:   408-974-4593
>
>"I speak only for myself, much to my employer's relief..."
>-------------------------------------------------------------

No, David is correct about ADB being handled by the other IOP.  The
SWIM PIC handles floppy i/o _and_ ADB.  It gives ADB priority, so the
mouse doesn't jerk most of the time, but it still can jerk during
floppy format verifies.

-- Carl


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