Xref: utzoo unix-pc.general:1949 comp.sys.att:5031 Path: utzoo!utgpu!watmath!clyde!att!osu-cis!n8emr!uncle!jbm From: jbm@uncle.UUCP (John B. Milton) Newsgroups: unix-pc.general,comp.sys.att Subject: Re: Second Hard Drive for UNIX-pc; HwNote10 Keywords: unix-pc hard-disk upgrade toes crunch ouch HwNote Message-ID: <450@uncle.UUCP> Date: 29 Dec 88 07:24:12 GMT References: <413@limbic.UUCP> Reply-To: jbm@uncle.UUCP (John B. Milton) Organization: U.N.C.L.E. Lines: 103 In article <413@limbic.UUCP> gil@limbic.UUCP (Gil Kloepfer Jr.) writes: [describes merciless feet stomping and how he got the 2nd hard drive going] I'm glad to see the schematic you got worked ok. Yeah, yeah, I've been slackin' lately. My design is now complete except for some board layout details. Now for the grubby details... Unlike the P5.1 upgrade, this upgrade CAN NOT be passive. Some wires just HAVE TO BE CUT FOR IT TO WORK! For older mother boards: 13N-1 must be clipped loose and connected to grounded. 13N-2 must be clipped loose and connected to 14M-3. This is actually an upgrade done by Convergent on later mother boards. For all mother boards: 13K-3 must be clipped loose from the board. Parts list so far: 1 double sided PC board 1 26LS31 differential line driver 1 26LS32 differential line receiver 1 16R8 PAL 2 16 pin sockets 1 20 pin socket 4 20 pin headers 2 34 pin headers 3 bypass caps 4 100 ohm resistors Other parts needed: 1 long 34 pin daisy chain cable with one header connector and at least two drive connectors 1 an internal 34 pin cable to go from the mother board header to the header on my board ? 20 pin data cables for each hard drive 1 external box and power supply Connections inside the UNIXpc: 1. Data bus line D1 2. Data bus line D2 3. Data bus line D3 4. The register select line MCR2SEL* 5. volts. 6. The hard disk read data line to the hard disk data separator PAL, 14M-3 7. The hard disk write data line, 16M-6 8. Maybe the RST* line. It will: 1. Add select lines for 3 more drives to the 34 pin cable. (total of 4 drives) 2. Provide a 34 pin header. 3. Provide active data connectors (20 pin) for 4 drives. 4. Work no matter how you mount it. (within reason) 5. Make you the envy of all your friends. It will not: 1. Provide P5.1 board version feedback. 2. Provide additional 4th head select bit. 3. Provide floppy tape support. 4. Provide a watch dog circuit. 5. Force you to take out your fan if you don't want to. 6. Cost too much. A price of $50.00 is what I'm shooting for now. 7. Affect the price of tea in China. Since the 3 drive selects have to be added to the 34 pin cable, the ground and DDRIVE0* line will be picked off of the 34 pin cable from the mother board. This will save two patch wires. I am assuming that your machine will have the "P5.1 FIELD UPGRADE" already installed. I will make that available as a SEPARATE kit. As I have mentioned in the HwNotes, you do not HAVE to have the P5.1 to use two drives. You DO have to have the P5.1 to format the second drive without swapping cables around. I plan to have a patch for the diag disk (3.5 and 3.51) by the time I start selling. The reason I am not providing the P5.1 on my board is that a lot of people already have the P5.1 installed. I also wanted to keep the number of wires going to my board down. The P5.1 part can be installed and tested separately, thus easing the upgrade process. I will be providing: the board, schematics, parts list, board layout, background, theory of operation, patch wiring instructions, formatting instructions, and probably a disk with HwNotes and other stuff. The text part of the instructions will be posted for review. Work is progressing on modifying the hard disk driver to USE all four hard drives. It will not be available with the initial release of the board, but will be posted in source form if and when I get it done. Until that is available, you will be restricted to only two hard drives. As far as the fan wars go, I have designed the board so that the cable headers will match up with the fan grates. I will recommend in my instructions that the fan be removed, the board be placed in that space, and that the existing internal hard drive be mounted in the external enclosure with the second drive. There will, of course be a melt down disclamer :) As always, it's never too late to get your opinions and advice in on the design of this board. If there are bugs found later, I would expect at least 50% of them fixable with a PAL change. Any of what I have described here may change between now and when I get evrything working. John -- John Bly Milton IV, jbm@uncle.UUCP, n8emr!uncle!jbm@osu-cis.cis.ohio-state.edu (614) h:294-4823, w:764-2933; Got any good 74LS503 circuits?