A4091 Reference
by Bob Emery
-----------------------------------------------------------------------------
The A4091 is a full-length Zorro-III DMA Fast SCSI-2 hard drive controller
designed for the A4000. It is based on the NCR 53C710 chip. (Editor's note:
this is the same Fast SCSI controller chip used in the Warp Engine.)
Unlike some similar products, it is only a Fast SCSI-2 controller; it has
no sockets for additional RAM. The A4091 package includes an active
terminator and a custom ribbon cable, which is nicely folded to accommodate
up to five internal drives, one on-board and a pair in each of the front
and rear bays.
The A4091 requires a revision 11 Buster, which Commodore supplied loose
with the card. It works with A3640 3.1 and 3.2 revisions, but not 3.0.
The board is theoretically capable of 10 Megabytes per second transfer
rates.
Board Layout
_________________________________________________________________
| ... ... LED ::::::::::::::: |___
| 50-Pin SCSI |
| ||| ||| ||| Connector |
| ||| ||| ||| ||| |#
| ||| |||||| |# External
| ||| ||| ||| ||| |||||| |# HiDensity
| ||| ||| ||| ||| |||||| |# SCSI-2
| |||||| |# Connector
| ||| ||| |#
| ||| ||| ||| |=sw 8
| ||| . Power |= :
| : Connector |= :
|_________________________________________________________________|=sw 1
|||||||||||||||||||||||||||||| |
LED Connectors
To DSPLY To MB
CN351 CN308
-------------------------
| o o o o o o
|
| N R B B R N
| C e l l e C
| d a a d
| c c
| k k
|
Unplug the Front Panel LED cable from the connector on the motherboard and
plug it into the CN351. To make the LED operate for IDE drives as well, use
the extra cable supplied with the A4091 to connect CN308 to the
motherboard.
Rear Connector View
---------------------------------------------------------------
| |
| DIP Switch External SCSI-2 Connector |
| _________________ |
| ON | | 1 25 |
| | 1 2 3 4 5 6 7 8 | {}:::::::::::::::::::::::::{} |
| OFF |_________________| 26 50 |
| |
---------------------------------------------------------------
DIP Switch Settings, defaults are all OFF
SCSI Address of Card
0 1 2 3 4 5 6 7
SW1 ON OFF ON OFF ON OFF ON OFF
SW2 ON ON OFF OFF ON ON OFF OFF
SW3 ON ON ON ON OFF OFF OFF OFF
SCSI Fast Bus
SW4 OFF indicates that the SCSI Fast Bus feature is enabled.
Set this switch to ON if none of your SCSI devices
support SCSI Fast Bus.
Short/Long Spinup
SW5 OFF indicates that your system uses the standard spinup
(booting) time. Set this switch to ON to request a longer
booting period. If one of your SCSI devices has a long
power-on cycle, the Amiga may not recognise it during the
standard booting period.
Synchronous Mode
SW6 OFF indicates that the synchronous mode feature is enabled.
Set this switch to ON to disable synchronous mode. Synchronous
mode does not require acknowledgement for every byte transmitted,
which can mean improved response time with most SCSI devices.
External SCSI Termination
SW7 OFF indicates that you do not have any external devices.
This activates the terminator on the board since this is
one end of the SCSI bus. Set this switch to ON when you
install an external device. This disables the termination
on the board since it is now in the middle of the SCSI bus
(not at the end).
Logical Unit (LUN) Enable
SW8 OFF indicates that unit 0 is the only unit recognized. Set
this switch to on to enable the system to recognize 1-6 as
LUNs.
Converted on 10 Aug 1996 with RexxDoesAmigaGuide2HTML by Michael Ranner.