Subject: Re: SCSI questions
To: Greg Cronau <>
From: Michael L. VanLoon -- Iowa State University <>
List: current-users
Date: 05/13/1994 22:33:43
>I am currently running Netbsd current from the Aprill 6th sources.
>My machine is as follows:
>	AMI Enterprise III EISA 486-66 with 12meg.
>	Bustek 747S EISA Fast-SCSI at 0x330, int-11, DMA-5
>	Adaptec 1542B ISA SCSI at 0x334, int-12, DMA-6
>2 days ago I opened the machine up to make 2 addtions: I added an additional
>8 meg of memory to bring the total to 20megs,

>5.) Does Netbsd properly handle DMA to ISA devices from memory beyond the
>    16mem boundary?

No.  It has been posted repeatedly that it doesn't.  The ISA bus
doesn't address more than 16 meg, and NetBSD doesn't yet do anything
to compensate for that.  Your EISA BusLogic card should work fine in
20 meg, but the ISA-bus Adaptec will only work if you have less than
16 meg.

>Weird question: Now that I have added the extra memory, I notice a couple
>of operations in X that actually seem alittle *slower*.

It's possible that your caching hardware is poorly designed.  There
are some cheap caches out there that will only cache the first 16 meg
of RAM.  Your last 4 meg might not be getting cached.


 Michael L. VanLoon                 Iowa State University Computation Center                    Project Vincent Systems Staff
  Free your mind and your machine -- NetBSD free Un*x for PC/Mac/Amiga/etc.