bc338569@longs.LANCE.ColoState.Edu (Brian Catlin) (03/25/91)
I would like to know if an SCSI controller uses the IRQ, DACK, and DRQ lines
to the computer. Please forgive me if this is "Common Knowledge" in this
group (I just joined 2 days ago).
Also, does anyone know if the other lines (Data, Address, MEMW, MEMR, etc)
are wired in parallel between card slots in an XT? Thanks in advance for
any and all replies.
B. J. Catlin
************************************************************
* Brian J. Catlin Electrical Engineering *
* e-mail : bc338569@longs.lance.colostate.edu *
* Compuserve : 73540,17 *
************************************************************neese@adaptx1.UUCP (03/28/91)
>/* ---------- "Signals to SCSI Controller" ---------- */ >I would like to know if an SCSI controller uses the IRQ, DACK, and DRQ lines >to the computer. Please forgive me if this is "Common Knowledge" in this >group (I just joined 2 days ago). Depends on the SCSI adapter. IRQ would certainly be used by all, but the DACK/DRQ lines are only used for DMA. Bus masters would use these signals, but PIO cards would not. Roy Neese Adaptec Senior SCSI Applications Engineer UUCP @ neese@adaptex uunet!cs.utexas.edu!utacfd!merch!adaptex!neese
gerry@zds-ux.UUCP (Gerry Gleason) (04/03/91)
In article <283400086@adaptx1> neese@adaptx1.UUCP writes: >>/* ---------- "Signals to SCSI Controller" ---------- */ >>I would like to know if an SCSI controller uses the IRQ, DACK, and DRQ lines >>to the computer. Please forgive me if this is "Common Knowledge" in this >>group (I just joined 2 days ago). >Depends on the SCSI adapter. IRQ would certainly be used by all, but the >DACK/DRQ lines are only used for DMA. Bus masters would use these signals, >but PIO cards would not. Correct me if I'm wrong, but bus masters would not use these signals, but would use "Bus Request" and "Bus Acknowledge" lines (whatever they are called on the bus). The DACK/DRQ lines are for "native" DMA, that is DMA managed by DMA chips on the system board. Note that this type of DMA is pretty slow, slower than what is possible with bus master DMA. Gerry Gleason