Subject: Re: Linux on CD

From: Andy Armstrong <[email-masked]>
Date: Tue, 19 Aug 97 16:55:14 +0100

There are a number of products:

8 bit SCSI regular podule, 8 bit SCSI micropodule, 8 bit SCSI minipodule, 
SCSI hardcard, 16 bit SCSI.

8 bit IDE minipodule, 16 bit IDE podule, 8 bit IDE Ultimate.

The 8 bit SCSI cards use a DP8490 controller (Nat Semi, 40 pin DIL 
package) in that chip's DMA mode. The micropodule version provides a 
memory mapped status register so you can poll DRQ. The other 8 bit cards 
have a horrid state machine which stalls the MEMC cycle while waiting for 
DRQ.

The 16 bit card has a NCR 53C94 or equivalent. The hardware of that card 
is involved...

The IDE cards work about the same way as everyone else's bog standard 
memory mapped IDE cards I expect :-) Only the addresses will be different.

The SCSI cards provide the standard Acorn SCSIDriver API and so work fine 
with CDFS. The IDE cards don't support CDROMs although I do have some 
working ATAPI code which never got released.

I would hazard a guess that it would be very easy to support the IDE 
interfaces and reasonably tricky to support the SCSI ones. The simplest 
SCSI interface to program is probably the 8 bit Micropodule.

-- 
http://www.wonderworks.co.uk --> Free RISC OS software
Andy Armstrong

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From: Alan Cox <[email-masked]>
Date: Tue, 19 Aug 1997 19:02:41 +0100 (BST)

> The 16 bit card has a NCR 53C94 or equivalent. The hardware of that card 

How involved - there is generic NCR5380/9x/400 support in the Linux kernel
that you basically provide the low level bits too

Alan

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From: Andy Fawcett <[email-masked]>
Date: Thu, 28 Aug 1997 14:02:37 +0000

In message <[email-masked]>
          Andy Armstrong <[email-masked]> wrote:

[HCCS cards]
> interfaces and reasonably tricky to support the SCSI ones. The
> simplest  SCSI interface to program is probably the 8 bit Micropodule.

:-)

Guess which SCSI interface I have?

-- 
Andy Fawcett                       a.f.p. recipes ([email-masked])
http://www.afawcett.demon.co.uk/       send mail with subject 'send index'
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