cmv@ihuxz.ATT.COM (Craig Votava) (01/20/88)
This is my 3rd try, again excuse duplicates... ------ I (re)posted all of this stuff last week, but our machine lost all of the articles, so I don't know who got it and who didn't. Please excuse all duplicates. All the articles that I talk about reposting, will appear in unix-pc.general and att.sys.unixpc ONLY. If you cannot get these groups, let me know what groups you do get, and I'll try and get you a copy somehow... ----- News saved at 5 Jan 88 21:29:26 GMT Many people have asked me to repost a number of upgrades that I've done to my unix-pc to make it do more than it originally could. I will try to summarize some of the upgrades that I've done, here in this article and then repost the original articles as well. I started with a used 7300 (0.5MBytes RAM, 20Mbyte Disk) in February of 1987 (bought just before the blowout sale... darn!) and have ended up with what is really a 3b1 I guess, 2.5MBytes RAM, 86Mbyte Hard Disk (I could have gone up to a 191Mbyte Disk, but didn't have the money!), DOS-73 board, and a Voice Power Board (These are really neat, I'd recommend them to anyone!). In order to get my machine to this point, I had to learn a lot about a wide variety of upgrades. EXPANSION MEMORY BOARD UPGRADE: The first problem I tried to solve with my system was to increase the amount of main memory I had in order to speed up the response time. I bought a used 0.5MB memory expansion board (thanks Gary!) which increased my total memory to 1 Meg. Then I found out that the exact same board populated with 256k chips instead of 64K chips (as mine was) could provide 2.0 Mbytes of memory! So, after some research into how to accomplish this, and screwing up my courage to do some hardware hacking, I ripped out all of the old memory chips, installed sockets and populated them with the higher density memory chips. Then I changed some jumpers on the board, installed it in my machine, and I ended up with a total of 2.5 Mbytes in my machine. I will re-post the original description of this upgrade. MOTHERBOARD MEMORY UPGRADE: During the course of my research into the above upgrade, I found out that the motherboard can be upgraded to hold a maximum of 2.0 Mbytes as well (that's a grand total of 4.0Mbytes in the machine). Early machines (like mine) were shipped with 0.5Mbytes of memory where all the available memory chip locations were populated with 64K chips. Later versions were shipped with 1.0Mbytes of memory where only half of the available memory chip locations were populated with 256K chips (the rest of the locations were left blank). For me to upgrade my machine, I'd need to rip out all of the 64K chips, and re-populate with 256K chips. This I was too scared to do initially, but am feeling better about it now, maybe someday I'll do this. To modify one of the later 1.0 Mbyte versions, all you have to do is add in the rest of the 256K chips. There are also jumper changes on any of these modifications. I will re-post the original description of this upgrade. EIA-RS232 RAM MEMORY EXPANSION BOARD UPGRADE: The eia-rs232 ram memory expansion board can be purchased in a number of different memory configurations from 0K memory, up to 1.5Mbytes of memory. It is also possible to upgrade a board on your own from any configuration up to 1.5Mbytes. I don't have any "official" upgrades on this, but I put together what I think would help to upgrade it. Back in August, ethos!fubar!cliff was trying to upgrade a 0K board (howze it going, Cliff?) I don't have a recent status on this. I will re-post the original description of this upgrade. 7300 TO 3B1 POWER SUPPLY UPGRADE: The second problem that I attacked in order to speed up response time, was to get a new Hard Disk. I decided to go with the Full-Height CDC WrenII 86Mbyte (9 heads, 925 cylinders) mainly for price reasons (thanks again, Gary!). I was worried about the power supply, since I'd heard rumors that the 7300 power supply was different than the 3b1 power supply, so I did some investigation to see what was what. According to the technician that I talked to, the 7300 and 3b1 power supplies are the same in every way except in how they deliver the power to the Hard Disk. On the 7300, all power is routed through the motherboard, so you have cables from the power supply circuit board to the motherboard, then other cables from the motherboard to the hard disk (as well as the floppy). On the 3b1, power for the hard disk comes off of a cable on the power supply circuit board directly into the hard disk, bypassing the motherboard totally. So I took my machine apart and looked at the power supply circuit board, and found that the holes for the cable to the hard disk are there and labeled! All you'd need to do is to remove the HD power supply cable from the motherboard and install it on the power CB, and you'd be all set! I decided to keep this as a last resort though, and simply connected my HD to the existing cable from the motherboard. I've had no problems, or unusual behavior, so never needed to perform this upgrade. HARD DISK CYLINDER CAPACITY UPGRADE: One limitation of the machine that can become a problem with all of the different sizes of ST-506 hard disks available now, is the maximum number of cylinders it can access. The hard disk controller chip originally installed in most unix-pc's was the Western Digital 1010 hard disk controller (WD1010). This chip physically cannot access more than 1024 cylinders on a hard disk. After talking with WD I found that they had a new chip that can replace the WD1010 and access more than 1024 cylinders - the WD2010. So, what this means is that if I went out and bought, say the MAXTOR XT2190 hard disk, installed it and tried to format it following the manufacturer's specifications (which indicate the drive has 1224 cylinders), the format program on the diagnostic disk would bomb out since the hard disk controller chip cannot access cylinders greater than 1024. The solution is to go to your friendly neighborhood electronics shop, and buy a WD2010 hard disk controller chip ($40.00), bring it home and replace your existing WD1010 chip with the new WD2010 chip. Since my hard disk has only 925 cylinders, I did not do this upgrade. I did however, try is out in a stock 7300 with the 20Mbyte hard disk, and everything worked properly - but that test didn't try formatting cylinders above 1024. I will re-post the original description of this upgrade. HARD DISK HEAD SELECT CAPACITY UPGRADE: Another limitation of the machine, that can be solved, is it's inability to access more than 8 heads on a hard disk. This problem hit me where I live, since the hard disk I installed in my machine had 9 heads; for a couple of months I had about 10Mbytes that I couldn't access! This upgrade took the most work to drag out of Convergent, and the most work to implement. Basically it involves installing a pre-programmed PAL chip in an unused location on the motherboard, and running jumper wires from the new chip to various locations on the motherboard. Since the upgrade fairly involved, and the equations to program the PAL chip with are proprietary to Convergent, I can/will not provide the upgrade via the net, but the upgrade instructions are not hard to acquire if you're persistent enough, and is not difficult to do, if you know your way around a soldering station. I will re-post the original description of this upgrade. BATTERY BACK UP REPLACEMENT: There have been a bunch of articles on how to do this, so I won't go into it in detail, but it involves going to Radio Shack and buying some re-chargable batteries and a battery holder and replacing the existing battery on the motherboard. Total cost is about $6.00 (Thanks Steve!) 2-WAY DATAKIT PORTS: A lot of very smart folks (thanks summit!) did a good deal of work to get 2-way datakit ports working on many AT&T machines (3b1,3b2,3b20,etc.). There are no hardware modifications, but I wanted to mention this because of the many questions I've seen on the net concerning this topic. The software is now available, for the 7300/3b1 through THE STORE (nice job Jonathan!). ******************************* Some other projects that I'm looking at are: ******************************* STREAMER TAPE UPGRADE: While talking with a buddy of mine, I found out that the streamer tape designed for the unix-pc has an interface that makes it look like a floppy disk drive. When you spend the megabucks to buy the streamer tape backup system from AT&T, you get the free standing streamer tape (with box and power supply) and a circuit board to connect it to. This circuit board must simply supply the unix-pc with another set of floppy disk connections, which we connect the streamer tape to and use the streamer tape software to drive the device. In theory then, I could rip out the floppy drive, and substitute a streamer tape, install the streamer tape software, create the /dev files with the appropriate major and minor numbers (if the software was written correctly) and be able to backup my hard disk to the streamer tape! If this assumption is true, what I'd like to do is to get the "Black Box Corp." to fabricate a switch box for me that will switch both the power, and the ribbon cable between 2 devices. Then I'll buy the streamer tape itself and connect it to one side of the switch, connect the internal floppy disk drive to the other side of the switch, and connect the cables from the motherboard to the "common" part of the switch. With this arrangement, I can select the floppy when I want to use it, or select the streamer tape when I want to do backups! Feel free to send me comments if you have any comments that could help me. 1200-2400 BAUD MODEM UPGRADE: I'm looking for a 2400 baud pin compatible modem chip to replace the 1200 baud modem we have in the unix-pc. This would be nice, but I don't know if it's feasable. Help here would be appreciated. That's all I have for now, feel free to send me questions, or send me help at [ihnp4!]looney!cmv or [ihnp4!]ihlpm!cmv Craig "looking-for-a-new-job" Votava IH 4G-324 x2542
richard@islenet.UUCP (Richard Foulk) (01/20/88)
> If this assumption is true, what I'd like to do is to get the "Black Box > Corp." to fabricate a switch box for me that will switch both the power, > and the ribbon cable between 2 devices. Then I'll buy the streamer tape itself > and connect it to one side of the switch, connect the internal floppy disk > drive to the other side of the switch, and connect the cables from the > motherboard to the "common" part of the switch. With this arrangement, I can > select the floppy when I want to use it, or select the streamer tape when I > want to do backups! Feel free to send me comments if you have any comments > that could help me. Floppy drives are designed to be bussed together. They normally have a couple of lines for drive-enable which is probably all you need to switch. That's why most multi-floppy systems connect the drives together via the same ribbon cable. So the job is much easier than it seems at first. -- Richard Foulk ...{dual,vortex,ihnp4}!islenet!richard Honolulu, Hawaii -- Richard Foulk ...{dual,vortex,ihnp4}!islenet!richard Honolulu, Hawaii