Redrumola,
The last 3 paragraphs are for you. You probably know more than I have forgotten, this is an issue that needs correction. Luckily, I downloaded almost 90% of National Amiga's Tech info. So, although they do not exist. I give them credit for the file content. (PS: this is 2 files, condensed).
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. [Editor's note: ROM revisions for the on-board ROM include 40.9 and 40.13.]
The board is theoretically capable of 10 megabytes per second transfer rates.
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.
The RAMSEY and DMAC chips are important A3000 custom chips that, among other things, implement part of the A3000's onboard DMA SCSI host adapter. Nearly all A3000 were delivered with the revision combination of DMAC-02 and RAMSEY-04.
The problem is in the DMAC, not in the RAMSEY and a RAMSEY-07 together with a DMAC-02 does not work at all. You need either both chips in the old revisions, or both in the new revisions.
The BUSTER chip (or more exactly Super-Buster), is important for the Zorro-III slots in your A3000. The revision
11 BUSTER implements Zorro-III DMA, so you can use the Fastlane Z3 or A4091 boards, which is not possible with older BUSTERs. The rev. 11 BUSTER is also faster than previous versions and more compatible with different plug in cards.
There is a BUSTER rev. 09 available, too. Do not buy this one, it also tries to implement Zorro-III DMA but has a bug in this. The rev. 11 part also is the only one, which has an extra hack to fix a bug in a different A3000 chip.
NVRAM
The A3000 has a small amount of nonvolatile RAM, that is used to store the settings for the onboard SCSI host adapter. Christian Just (just@zfn.uni-bremen.de) reported, that he heard of several cases where the contents of this RAM were lost when an A3640 was installed. This resulted in SCSI problems, that vanished when the settings were restored with the SetBatt
utility. It is available as util/wb/SetBatt-1.2.lha on Aminet. As I can not confirm this and have no exact knowledge what is happening here, I would appreciate any further information about this battmem problem.
NATIONAL AMIGA TECHNICAL INFO
