Re: IDE CD-ROMs

[jwt@example.com (Jim Tittsler)]

In article <m0szuSW-0004NeC@example.com>,
turnbull@example.com (Stephen J. Turnbull) wrote:
> >>>>> "Jim" == Jim Tittsler <jwt@example.com> writes:
> 
>     >> disk.  Works good.  Ran into trouble when it didn't have a
>     >> driver for my IDE NEC cd-rom (hah, teaches me to buy IDE stuff ;)
>     >> ), anyways, I wasn't
> 
>     Jim> SCSI is definitely out-dated.  Linux works fine with the NEC
>     Jim> IDE CD-ROM that came with my Gateway machine and with the
>     Jim> much better ones from Creative Technology that I designed.  :-)
> 
> Uh-huh.

I meant my posting partly in jest, given the source of the original joking
criticism.  I was trying to point out that ATAPI CD-ROMs are well-defined
and well-supported (DOS, Linux, OS/2, NT).

> I have 8 devices hanging off my AMI SCSI host (2 floppies, a

True.  Each IDE bus can support only two devices.  The first two IDE
host adapters are at well-defined locations/interrupts, the third and
forth adapters have become "defacto" standards thanks to Novell.

> Scanjet).  Even though it was a slow (50Mhx '486) processor on a slow
> (EISA) bus, it still blew the typical early Pentia with EIDE drives at
> the OSU Econ department out of the water on disk I/O.  (The 4MB cache
> had a lot to do with that, of course.)  There may be more stuff coming

It depends a lot on the host adapters (and SCSI variety) being compared.
IDE is only a 16-bit wide data path.

> follow the hardware wars, though.  I had the vague impression that the
> new IDE stuff was basically a bag on a kludge on a wart on a frog on a
> bump on a log in a hole in the bottom of the sea.

ATA (IDE) has been significantly better codified in the past 2 or 3
years with the ratification of an ANSI standard. ATAPI is an almost
SCSI-esque packet protocol that uses some of the previously unused
ATA op-codes.  ATAPI is used by CD-ROMs and tape drives (and soon CD-R).
It was defined early enough that it quickly replaced a variety of competing
incompatible ways of reusing the ATA bus for non-hard-disk devices.

> This is not so?  What architectures are IDE hosts available for
> besides iAPX + *ISA/PCI bus (are we really all going to move up to '686
> and '786, or are we going to do Alphas and PowerPCs, ne)?  Are those

PCI is a mezzanine bus.  It does not presume the x86 architecture.
It is appearing in PPC and Alpha machines.  ATA (IDE) is also not
tied to the x86.  ATA drives have been used in Atari and Amiga 68xxx
machines.

>     Jim> Kernels after about 1.1.8x have included native support for
>     Jim> IDE CD-ROMs.
> 
> Which ones?  Or is there an IDE standard that means something, ie,
> that essentially all reputable manufacturers implement correctly?

The vast majority of ATAPI CD-ROMs implement the ATAPI standard
reasonably correctly.  We are beaten into line by Microsoft and 
IBM so that we work with their device drivers.

Jim