SCSI BLUES ~~~~~~~~~~ by Chris Searle ~~~~~~~~~~~~~~~ Ed: More enlightenment on the black art of SCSI termination and other arcane matters - Chris has done it the hard way so that you may have it easy, so read on! 37 :*: 37 :*: 37 :*: 37 :*: 37 :*: 37 :*: 37 :*: 37  Biopic ------ I am a middle-aged grandfather with an interest in home computing which took off when I purchased a Commodore 64 in 1984. I have been a Government lawyer for the last 9 years. Before commencing to practice law I was a survey and engineering draftsman for 20 years. My present computer system comprises an Amiga 1000 fitted with a Phoenix motherboard, Kickstart and disk drive swap switches, 1 MB ECS, ATOnce MSDos emulator board, 3MB Fast RAM (2MB External), external floppy disk drive, 52Mb internal and 121Mb external SCSI hard drives, 1081 monitor and Star NX1000 printer. I also have (and still use) a Commodore 128 and 1571 disk drive (fitted with Jiffy Dos). The Commodore 128 shares the 1081 monitor and also the printer (via a printer switch box and Zetec Super Graphix Gold Interface). Sound output from the C128 is through the mono speaker in the 1081 monitor, whilst the stereo output from the A1000 is connected direcly to a small Realistic amplifier and desktop speakers beside the 1081 monitor. The two computers and peripheral equipment are all housed neatly in a corner cabinet made by me specially for this purpose. On MegaDisc 32B there is a very helpful article by Randall King on SCSI termination problems. The article is appropriately titled 'The mysteries of SCSI Termination'. If you are having any difficulties with your SCSI hard drive or other SCSI device you should read Randall's article. If you are about to add another SCSI hard drive or other SCSI device to your system I strongly suggest you read what Randall has to say about correctly terminating SCSI devices. It might just save you the trouble I experienced when adding a second SCSI hard drive to my system. I have an Amiga 1000 which I purchased in 1987 (Goodness! - was it that long ago). In 1991 I upgraded the A1000 by installing a Phoenix motherboard and a SCSI Quantum 52 Mb hard drive, all from Phoenix Microtechnologies in South Australia. That was the start of my SCSI blues. The Phoenix Board I purchased originally came fitted with Phoenix Microtechnologies' proprietary SCSI device controller version 'E' EPROM on the motherboard. Everything worked fine until I installed an ATOnce Classic MSDos Emulator Board and formatted and partitioned the hard drive as DH0 (25 Mb Amiga partition) and DH1 (25 Mb MSDos partition). Although the Amiga booted correctly at start-up from the Amiga partition, I simply could not get ATOnce to boot MSDos directly from the DOS partition of the hard drive (DH1). This was despite assurances from John Fonhoff (the distributor for ATOnce in Australia) and Phoenix that the ATOnce board should work Ok with my system. After making repeated checks that I had installed everything correctly and trying various changes to my mountlists and installation configuration, I resigned myself to the fact that I would have to boot ATOnce from floppy disk. Some months later I purchased from Phoenix and installed their Version 'I' release of the Phoenix Board SCSI driver so I could do away with mountlists to mount the DH0 and DH1 partitions of the hard drive. This version of the Phoenix SCSI driver implements Commodore's Rigid Disk Block standard for boot-time mounting of partitions. As far as I can tell, it is also completely compatible with HDToolBox after the Tool Type for HDToolBox is changed to 'SCSI_DEVICE_NAME=pbscsi.device'. SURPRISE, SURPRISE! AtOnce now booted directly from the MSDOS partition of the internally fitted hard drive. The fault all along must have been with the version 'E' of the Phoenix Board SCSI controller. I can only advise that if you have an Amiga 1000 with a Phoenix Board fitted with a SCSI controller earlier than version 'I', you should upgrade immediately (although 'upgrade' isn't really the right word - it is more a case of paying Phoenix for the privilege of getting a bug-free SCSI controller which is what you should have got when you purchased the Phoenix Board in the first place). After that little glitch in my computing fun, everything went along fine until I started to run out of memory storage on both partitions of the hard drive. What to do!. I seemed to have two choices. Replace the 52 Mb Quantum with a larger capacity drive or keep it as an internal hard drive and buy an additional SCSI hard drive to be connected externally to the A1000. I opted for the latter. I decided I would be loyal to our editor and purchase the additional hard drive in external case from him, sight unseen. I haven't regretted this decision. Tim gives excellent service, he can be trusted not to sell you a lemon and his hardware prices are competitive (a deserved plug for Megadisc). The hard drive unit Tim supplied is a 121 Mb SCSI Quantum in a sturdy metal case with the brand name 'Maxima' and came with a separate SCSI cable connected to a SCSI terminator plug. Software was included for using the hard drive with a Macintosh, but not for an Amiga. There were no instructions for connecting the hard drive to a computer or other SCSI device and nothing about how to terminate it. I asked Tim whether there was anything I should do when connecting the hard drive unit to my Amiga to ensure it was correctly terminated. Tim's reply was to the effect that SCSI termination was a bit of a black art! However, he did confirm that I should unplug the SCSI terminator plug from the SCSI cable, plug the cable into any one of the two DB25 sockets at the back of the hard drive unit and plug the terminator plug into the other socket if no other SCSI devices were to be connected to the hard drive unit. So far, so good! But before I could connect it all up I had to install an external DB25 socket in the back of the A1000 case and connect this socket internally to the additional SCSI controller socket on the Phoenix motherboard. As Phoenix Microtechnologies supply the cable and sockets for this purpose already made up (and being too lazy to do it myself - though if you want to save a couple of dollars, even blind freddy could do it from parts purchased from ACAR or another electronics supplier), I ordered the necessary part from Phoenix. While waiting for Phoenix to send me the cable (they always seem to take two weeks from date of order to date of delivery - Megadisc had the hard drive delivered in 48 hours!), I decided I would install Kickstart and Workbench 2.04 at the same time. I have lost track of the number of times I have had to open up the A1000. I reckon I could do it in my sleep by now. I purchased the 2.04 Kickstart/Workbench upgrade from Microcomputer Spot (good manuals for a change!) and waited for the SCSI cable from Phoenix. When it arrived I put it all together and connected the external SCSI hard drive. HORRORS of HORRORS - nothing worked!. What to do? I am always careful about properly earthing myself before opening up and mucking about inside the A1000 case so I was reasonably confident that I had not accidentally fried the 68000 processor or some other chip. No solution came immediately to mind, other than rushing off to the nearest Commodore Service Centre, so I slept on the problem. The next day I opened up the A1000 case to have a look (though I had no idea what I was supposed to be looking for). The AtOnce board seemed to be slightly askew in the 68000 socket. I pushed it firmly back home and switched on the computer with the monitor connected but with the lid and RF shield still off and the internal hard drive and other peripherals disconnected. Problem solved - the ATOnce board had become dislodged! I put everything back together, reformatted and configured both hard drives to use the Fast File System, created an MSDOS partition on the external hard drive for ATOnce, installed Workbench 2.04 on the internal hard drive and restored all Amiga files to the internal hard drive and all MSDOS files to the MSDOS partition (now DH2) on the external hard drive. Hallelujah!. Everything worked and Workbench 2.04 looks so much better than 1.3. Well almost! - when I tried to boot ATOnce from the MSDos partition of the external hard drive the dreaded GURU appeared and the A1000 crashed. Thank God (or whoever) for the Kickstart swap switch I purchased and installed as an option with the Phoenix Board. AtOnce will still boot from the hard drive if I use Kickstart 1.3 but not if I switch to Kickstart 2.04 and try to use Workbench 2.04. John Fonhoff reckoned the ATOnce Classic Board should work with Kickstart and Workbench 2.xx., but I reckon he is wrong (yet again). I purchased an upgrade to the ATOnce Classic software from him but this made no difference. The latest version of this software is supposed to have been released into the public domain and Megadisc (our editor) has it on disk number VT364 - but his disk has a read/write error so don't waste your time ordering it from him (I did - twice!). Sorry Tim, but you stuffed up on this one. Has any one out there been able to get ATOnce Classic or ATOnce Plus to work under Kickstart/Workbench 2.xx or 3.xx? Everything then went along fine until I started to fill up the external hard disk. The whole system became very flaky. Sometimes the external hard disk would be recognised and mounted on boot-up, sometimes not. Occasionally the external hard drive would lock-up when reading or writing to the drive. Very frustrating, though fortunately the integrity of the data on both hard drives remained intact.  Megadisc to the rescue! I had remembered reading Randall King's article about SCSI termination problems so I read it again - this time more carefully. Could it be that the comb-like resistors that Randall mentioned in his article were still plugged into the internal Quantum drive. When I thought about it, that seemed to be likely. After all, when I only had the internal hard drive (and at that time, the only device in the SCSI bus chain apart from the controller on the Phoenix board) how else could it have been terminated as the last device in the chain? I opened up the A1000 (yet again), disconnected the internal hard drive and had a look. Sure enough, underneath the 50 pin dual-row socket (header) at the back of the drive were the offending black comb-like resistors (terminators) still plugged in. I removed these resistors (there were two or three of them in-line) and put everything back together again. Needless to say, that cured my SCSI blues. I now have two SCSI devices connected in daisy-chain fashion which are properly terminated at each end of the chain. I have encountered no more problems with my system. Because the external hard drive case has both a power-in and power-out socket (a la IBM), I have the A1000 powered via the power-out socket on the external hard drive case. This ensures that the external hard drive is switched on before or at the same time as the A1000 and is always recognised and mounted at system start-up. After solving my problems I looked back in the documentation supplied by Phoenix to see if any advice was given about adding more SCSI devices. There was nothing in the manual originally supplied with the Phoenix board. But the following comment does appear in a chapter4.doc file on an upgrade disk from Phoenix that came with the revision I of the SCSI EPROM and the disk-based pbscsi.device: "External devices each have two DB25 ports so that they can be connected in daisy-chain fashion. Make sure their IDs do not conflict with each other or the internal drive. The terminators (usually resistor packs) on SCSI devices NOT at the extreme ends of the bus should also be removed." Just a bit cryptic, don't you think? I now understand what Phoenix is saying but I probably didn't when I first read the file (if I read it at all!). As I often remark to others - When all else fails...Read the Instructions! About the Maxima Hard Drive Unit: -------------------------------- It is a well built strong unit that looks at home with the A1000. The case styles and colours are similar. The Quantum hard drive installed in the case has a respectable seek and read speed and works very well (it will sequentially seek and read one sector in 7.77 milliseconds, compared to a time of 7.70 milliseconds by the internal 52Mb Quantum drive I purchased with the Phoenix motherboard). There are two DB25 sockets at the back of the case so you can connect another SCSI device in daisy-chain fashion to the unit, such as a CDROM drive. And the power-out socket at the back of the case is great for keeping all those connecting power cables to a minimum and simplifying switching on the system. I really only have three complaints about the Maxima unit. The power-on and drive activity lights are respectively green and red - the opposite of the A1000 and external floppy drive (very confusing); the case is dimensioned to fit neatly under a Macintosh but because of this it is a little bulky in size; and the internal fan is very noisy. I should be able to fix the LEDs by swapping them but this will require some cutting and resoldering of the connecting wires. I haven't bothered to do this yet. I solved the case size problem by making a neat timber stand the same width as the base of my 1081 monitor. The hard drive unit sits underneath with easy access to switch and sockets on the back and the monitor sits on top - very stylish! The timber stand has also reduced some of the fan noise. For a more drastic solution to this problem see the Noisy-Fan-Fix article by Warren Bell on Megadisc 32B.  That's all Folks! Chris Searle, P.O. Box 197 Merrylands NSW Australia 2160 37 :*: 37 :*: 37 :*: 37 :*: 37 :*: 37 :*: 37 :*: 37