Re: Triton DMA

Gerard Roudier (
Sun, 30 Nov 1997 18:12:46 +0100 (MET)

On 30 Nov 1997, Linus Torvalds wrote:

> In article <65q0g9$6nu$>,
> H. Peter Anvin <> wrote:
> >
> >I guess I don't really understand the quest to turn IDE into SCSI,
> >especially since SCSI is *still* very much more versatile than IDE; I
> >have yet to see an IDE scanner...
> Well, SCSI may be more versatile, but I have yet to get a single report
> about problems with IDE because of bad termination.

If we turn SCSI versatility into IDE non-versatility by doing the

- Solder a terminator on every SCSI controller.
- Change 'Terminator enabled' jumper to 'Secondary'
'Terminator disabled then means 'Primary'
- Allow 2 devices max per controller.
- Use a different connector at controller connection cable end.
- Donnot provide an external connector.

Then I am pretty sure we will not get more reports about SCSI than
about IDE.

IMO, the more something is versatile, the more the risk to use a bad
configuration exists.
Btw, I have far less problems using my pocket calculator than using
Linux, but I am quite happy of Linux. ;-)

> The fact is that neither IDE not SCSI is perfect. IDE wins hands down
> in price and ease of use, while SCSI wins on high-end performance and
> flexibility. Which one you consider to be more important depends on the
> use.

About prices I have recently observed in France these ones:

IBM DCAS 4.3 GB UW SCSI 256K cache 2400 FF
IBM DAQA 4.3 GB Ultra DMA 128K cache 1690 FF

Seems we get what we pay nowadays.

> There are lots of people who think that SCSI is inherently better.

I am one of them.

> Personally I consider that to be a very limited view of the situation.


> As to IDE scanners - a few years ago the selling point of SCSI oevr IDE
> (at least according to SCSI proponents) was that you could buy CD-ROM
> drives etc for SCSI without having to buy an extra card. Anybody who
> buys a SCSI CD-ROM these days has too much money and too little sense..

Very cheap IDE CD-ROM drives use bad quality mechanical components.
They generally are not available with an SCSI interface.
For good quality CD-ROM drives the difference between IDE and SCSI is not
that high. But I agree that the IDE interface is most of the time enough
for systems that need only 1 CD-ROM drive. And when hard disks are SCSI,
this will spare SCSI BUS bandwitch since CD-ROM drives generally
negotiate only 5MB/sec or less on SCSI.

Lots of SCSI Scanners provided with a SCSI controller have lousy firmware.
So, it is often recommended not to share this SCSI controller with other
SCSI devices.

> IDE has had a _lot_ of development due to mass market issues. Many
> technical people look at technical specifications rather than at market
> issues, and that's not necessarily the best thing to do.
> Linus