ahc(4)
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AHC(4) NetBSD Programmer's Manual AHC(4)
NAME
ahc - Adaptec VL/EISA/PCI SCSI host adapter driver
SYNOPSIS
For VL cards:
ahc0 at isa? port ? irq ?
For EISA cards:
ahc* at eisa? slot ?
For PCI cards:
ahc* at pci? dev ? function ?
To enable tagged queueing:
options AHC_TAGENABLE
To enable SCB paging:
options AHC_SCBPAGING_ENABLE
For SCSI busses:
scsibus* at ahc?
DESCRIPTION
This driver provides access to the SCSI bus connected to an Adaptec 274x,
284x, 2940, 3940, or controllers based on the AIC7770, AIC7850, AIC7860,
AIC7870, or AIC7880 host adapter chips. Features include support for
twin and wide busses, ultra SCSI, two active commands at a time per non-
tagged queueing target, tagged queuing, and SCB paging which allows up to
255 active commands on all adapters except those using AIC7770 chips pri-
or to revision E. Tagged queueing is enabled with the ``AHC_TAGENABLE''
configuration option. SCB paging is enabled with the
``AHC_SCBPAGING_ENABLE'' configuration option.
Per target configuration performed in the SCSI-Select menu, accesible at
boot in non-EISA models or through an EISA configuration utility for EISA
models, is honored by this driver with the stipulation that the BIOS must
be enabled for EISA adaptors. This includes synchronous/asynchronous
transfers, maximum synchronous negotiation rate, disconnection, and the
host adapter's SCSI ID.
Note that I/O addresses are determined automatically by the probe rou-
tines, but care should be taken when using a 284x (VESA local bus
controller) in an EISA system. Ensure that the jumpers setting the I/O
area for the 284x match the EISA slot into which the card is inserted to
prevent conflicts with other EISA cards.
BUGS
Some Quantum drives (at least the Empire 2100 and 1080s) will not run on
an AIC7870 Rev B in synchronous mode at 10MHz. Controllers with this
problem have a 42 MHz clock crystal on them and run slightly above 10MHz,
causing the drive much confusion. Setting a maximum synchronous negotia-
tion rate of 8MHz in the SCSI-Select utility will allow normal function.
SCSI residual handling is not complete on NetBSD version of this driver.
SEE ALSO
intro(4), aha(4), ahb(4), cd(4), scsi(4), sd(4), st(4)
AUTHOR
The ahc driver was written by Justin Gibbs. The AIC7xxx sequencer-code
assembler was written by John Aycock. NetBSD porting is done by Stefan
Grefen, Charles M. Hannum, Michael Graff, Jason R. Thorpe, Pete Bentley
and Noriyuki Soda.
HISTORY
The ahc driver appeared in FreeBSD 2.1 and NetBSD 1.1.
NetBSD 1.4 April 20, 1996 2
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