›7mCommodore A4091 SCSI Host Adaptor ›0m ----------------------------------------------------------------------------- Commodore A4091 SCSI Adaptor ----------------------------------------------------------------------------- This page was added specifically because so many people appear not to actually have any documentation on the 4091. I know, because I'm the one who had to answer all the queries in #amiga on IRC :) The 4091 was licensed to DKB who built it for a while as well. This documentation refers specifically to the Commodore version as I'm not sure what changes DKB made to the design (if any.) I'm trying not to break any copyright with Commodore's original documentation, but I do need to try to get the information across, so give me some leeway if I stray :) ----------------------------------------------------------------------------- ›7mAvailable topics are: ›0m ›7mFeatures ›0m ›7mDipswitch Settings ›0m ›7mPin Outs ›0m ›7mFirmware Revisions ›0m ›7mGeneral Questions ›0m ›7mTrouble shooting ›0m ›7mWho Designed it? ›0m ----------------------------------------------------------------------------- ›7mFeatures ›0m Full Zorro III support SCSI-2 support Internal 50 pin SCSI connection External High density SCSI Connector (aka Mini-D 50) Direct Memory Access (DMA) for fast transfers Mounting support for 3.5" harddrive on the card ›7mDipswitch Settings ›0m Board's SCSI Address (Switches 1,2,3) ID 0 -- 1 ON ; 2 ON ; 3 ON ID 1 -- 1 OFF; 2 ON ; 3 ON ID 2 -- 1 ON ; 2 OFF; 3 ON ID 3 -- 1 OFF; 2 OFF; 3 ON ID 4 -- 1 ON ; 2 ON ; 3 OFF ID 5 -- 1 OFF; 2 ON ; 3 OFF ID 6 -- 1 ON ; 2 OFF; 3 OFF ID 7 -- 1 OFF; 2 OFF; 3 OFF (Default) SCSI Fast Bus (Switch 4) OFF = SCSI Fast Bus enabled. ON = SCSI Fast Bus disabled. Set this if none of the devices on the SCSI chain support SCSI Fast Bus. Short/Long Spinup (Switch 5) OFF = System uses standard spinup booting time ON = System uses longer booting period. Set this if one of the SCSI devices is not recognised under a shorter booting period. Syncronous Mode (Switch 6) OFF = Mode is enabled. This means that not evey byte sent over the SCSI bus is acknowledged leading to improved response times. ON = Mode is disabled. External Termination (Switch 7) OFF = Termination is turned ON. This means you do not have any external SCSI devices. ON = Termination off. This means you do have external devices and the last one must be terminated. Logical Unit (LUN) Enable (Switch 8) OFF = Unit 0 is the only unit recognised. ON = Units 1-6 are now recognised. This is essential is you have a multiple unit device in your SCSI bus such as a CD-ROM jukebox. Otherwise only the first CD will be recognised. ›7mPin outs ›0m 1 Ground 26 /DB(0) 2 Ground 27 /DB(1) 3 Ground 28 /DB(2) 4 Ground 29 /DB(3) 5 Ground 30 /DB(4) 6 Ground 31 /DB(5) 7 Ground 32 /DB(6) 8 Ground 33 /DB(7) 9 Ground 34 /DB(P) 10 Ground 35 Ground 11 Ground 36 Ground 12 Reserved 37 Reserved 13 Open 38 TERMPWR 14 Reserved 39 Reserved 15 Ground 40 Ground 16 Ground 41 /ATN 17 Ground 42 Ground 18 Ground 43 /BSY 19 Ground 44 /ACK 20 Ground 45 /RST 21 Ground 46 /MSG 22 Ground 47 /SEL 23 Ground 48 /C/D 24 Ground 49 /REQ 25 Ground 50 /I/O ›7mFirmware Revisions ›0m The most recent ROM is 40.13. Thanks to ›7mPaul Reeves ›0m of ›7m Asimware Innovations ›0m for that. ›7mGeneral Questions ›0m What's the device name for the 4091? 2nd.scsi.device -- Make sure you type it exactly. Why isn't it in DEVS:? It's ROM based. This means that the machine can boot off a drive installed on the 4091. If it was a disk file, you'd have to load it from disk first. But since you don't have a harddisk since the 4091 isn't recognised yet, you'd have to boot from floppy (or the internal IDE drive...if you still have one!) Which way in does the external connector go? Sensibly enough, there's only one way it will fit physically, and that's the correct way. But for those who really want to know, looking from the back on the 4000, pin 1 is on the top left corner where the housing is widest. Pin 25 is on the top right, pin 26 in on the bottom left, and pin 50 is on the bottom right. ›7mTroubleshooting ›0m System has a nasty habit of hanging on disk accesses. You've not terminated the bus correctly. Check to see if you have used either the internal terminator supplied with the 4091 or that the last internal device has its own termination set. Then check the external termination. Check your cabling. Bad cabling causes more SCSI problems than just about any other cause and it's a pain to track down until you realise that. Ensure that you don't have any SCSI ID conflicts. You have more than one Zorro 3 DMA device (such as a Cybervision 64). If possible, put that other device into a slow mode. The 4091 doesn't like my machine. You are using an Amiga 4000 aren't you? Using the 4091 with the 3000 is possible, but not recommended. Make sure you have the Rev 11 Buster chip (if you're facing the 4000 from the front, it's to the left of the slots about half way to the back of the machine. The suffix should be -11. If it isn't, try to find a replacement from one of the parts companies. ›7mDesigners ›0m Data not available. I've not opened up the 4000 recently to look at the names on the PCB :) ----------------------------------------------------------------------------- This page was last updated on the 20th of June. For comments, corrections and additions, please send email to ›7m adamh@spots.ab.ca ›0m