** This is the quasi-official and semi-temporary T13 email list server. **
The problem is in distinguishing line "d" from line "f" in your tables.
All that has ever really needed to happen is to change the signature
display following a reset so that the host can tell whether or not it
is looking at case d or case f. That's all this is supposed to
address.
Tons and tons and tons of atapi devices have been doing that for
years and years and years. It works and it is better than what got
put into ata/4 and 5. In my opinion, ATA-4 and ATA-5 missed the
simple fact that case d and case f are indistinguishable from each
other.
It was at *your* behest Hale, that the register response tables were
changed so that atapi device 0 when answering for device 1 returned
00h for every register read.
Device hardware has always been required in the case of device-0
answering for device-1 to place a 00h on the bus for the status and
alternate status register. I don't know how hard it is to extend this
behavior in hardware for the rest of the taskfile.
Seriously, since I was the one pressing this, as far as I am
concerned an atapi device-0 that answers for device-1 with an invalid
signature in CL or CH for device-1 (to distinguish line d) is doing
what I need for it to do.
The rest of the time, I don't care what it does as long as it doesn't
process commands or set values in the status/alt status registers
when a non-existent device-1 is accessed.
> ** This is the quasi-official and semi-temporary T13 email list server. **
>
>Be careful, there were typos in some versions of these tables. I
>have attempted to correct those typos below. The notation (none,
>none*, RDY, etc) are same as in the email previously posted here
>(also reproduced below the tables).
>
>The following table shows what ATA-1 through ATA/ATAPI-5 specify.
>
># dev0 SC SN CL CH ST ST2 dev1 SC SN CL CH ST ST2
>a ata 01 01 00 00 00 RDY none* 01 01 00 00 00 00
>b ata 01 01 00 00 00 RDY ata 01 01 00 00 00 RDY
>c ata 01 01 00 00 00 RDY atapi 01 01 14 eb 00 00
>d atapi 01 01 14 eb 00 00 none* 01 01 14 eb 00 00
>e atapi 01 01 14 eb 00 00 ata 01 01 00 00 00 RDY
>f atapi 01 01 14 eb 00 00 atapi 01 01 14 eb 00 00
>g none ?? ?? ?? ?? ?? ?? none ?? ?? ?? ?? ?? ??
>h none ?? ?? ?? ?? ?? ?? ata 01 01 00 00 00 RDY
>i none ?? ?? ?? ?? ?? ?? atapi 01 01 14 eb 00 00
>
>The following table is what ATA/ATAPI-6 currently specifies.
>
># dev0 SC SN CL CH ST ST2 dev1 SC SN CL CH ST ST2
>a ata 01 01 00 00 00 RDY none* 01 01 00 00 00 00
>b ata 01 01 00 00 00 RDY ata 01 01 00 00 00 RDY
>c ata 01 01 00 00 00 RDY atapi 01 01 14 eb 00 00
>d atapi 01 01 14 eb 00 00 none* 00 00 00 00 00 00
>e atapi 01 01 14 eb 00 00 ata 01 01 00 00 00 RDY
>f atapi 01 01 14 eb 00 00 atapi 01 01 14 eb 00 00
>g none ?? ?? ?? ?? ?? ?? none ?? ?? ?? ?? ?? ??
>h none ?? ?? ?? ?? ?? ?? ata 01 01 00 00 00 RDY
>i none ?? ?? ?? ?? ?? ?? atapi 01 01 14 eb 00 00
>
>Note that the only difference in the tables is in line d.
>
--
---------------------
"Anything you CAN control you MUST control."
Wendy Carlos
---------------------
Larry Barras
Apple Computer Inc.
1 Infinite Loop
MS: 306-2TC
Cupertino, CA 95014
(408) 974-3220
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