Subject: Re: Accelerator cards and mice...
To: None <port-mac68k@netbsd.org>
From: Michael G. Schabert <mikeride@prez.org>
List: port-mac68k
Date: 10/28/1998 16:31:23
>>
>> would that be done by a PDS slot card or by board exchange? A simple
>>processor
>> exchange would not work - at least IMHO . . .
>>
>> If by pds slot card, I remember there are some creating problems with
>>NetBSD (Carrera?).
>>
>> Best regards,
>>
>> Ulrich
>>
>Dear Ulrich,
>
>I think the board exchange path w/ IIci is with a Quadra 700, so
>I'm surprised the clock speed is not 50 Mhz.  As for using the PDS
>slot, currently, I actually have a custom kernel that boots NetBSD
>('040 @ 90 Mhz), but unfortunately something within the SCSI driver
>disagrees with the accelerator, so reads work, but writes do not.
>It's as close as I have gotten.  There have been fixes to SCSI drivers,
>so I'm waiting for the next release of the source to try again.

The 25 Mhz versus 50 Mhz is not a different speed issue. It's a semantics
issue. Until the very last year of 68k Macs, Apple never advertised the
internal clock speed of the machines, but rather gave out the external
speed (how fast it computes versus how fast it talks to the bus). Intel
jumped out of the gate with the DX2 and DX4 by advertising the internal
speed (double & triple-speed respectively. That's why 68k Macs are
generally considered to be about twice as fast per clock speed as their 486
counterparts. Apple advertised the Q700 as a 25 Mhz machine.

On a similar note, did you clock-chip the '040 in your PDS? I've never seen
an '040 accelerator advertised even as fast as the 840AV's 80 Mhz (Apple
advertised it as 40 Mhz). The fastest acelerator I knew of was the quad
doubler.

Mike
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