Path: utzoo!utgpu!watserv1!watmath!att!bellcore!rutgers!cbmvax!valentin
From: valentin@cbmvax.commodore.com (Valentin Pepelea)
Newsgroups: comp.sys.amiga.tech
Subject: Re: Diskperf with A3000
Keywords: Strange behavior of Diskperf
Message-ID: <12763@cbmvax.commodore.com>
Date: 16 Jun 90 01:59:12 GMT
References: <1512@ramz.UUCP> <12526@cbmvax.commodore.com> <404@nyit.UUCP>
Reply-To: valentin@cbmvax (Valentin Pepelea)
Organization: Commodore, West Chester, PA
Lines: 31

In article <404@nyit.UUCP> aca@nyit.UUCP (Al Arthur) writes:
>In article <12526@cbmvax.commodore.com> jesup@cbmvax (Randell Jesup) writes:
>>
>>	Check to make sure the mask for the partition is 0xfffffffc.  If it's
>> 0xfffffe, then it's set up wrong.
>
> I never did figure-out what the mask was really used for,  nor what it
> should be set to on my machine.  Can you explain it to me? (Thanks)

The mask value specifies to what addresses a DMA device may DMA into. A mask
value of 0xfffffe means that DMA transfers are restricted to the lower
16Meg address space, word-long transfers please. A value of 0xfffffffc means
that DMA transfers may be made to the entire 4 Gigabyte address space,
long-word transfers please.

Randell was talking about the mask value suggested for A3000's. On these
computers, since fast memory resides above the 16Meg boudare, the 0xfffffe
mask value effectively restricts DMA transfers to CHIP memory. 

> I have a 2090A, and early docs on it that don't seem to contain complete
> information about the Mountlist entries. My machine has a 2630, 2090A,
> 1)2052, 2) SCSI Disks, 1)TapeDrive

On other computers, leave the mask value to the factory preset.

Valentin
-- 
The Goddess of democracy? "The tyrants     Name:    Valentin Pepelea
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