Sprague.Wbst311@XEROX.COM (10/26/90)
Grumble! This bounced the first time. It's a little late, but still applies. -------------------------------- In reference to the card in Steve's Xerox 820-II, and in the spirit of general information sharing (I saw some incorrect info), I have written the following note. :-) --------- As has been pointed out, the Xerox 820 has NO card edge slots. The 820-II, 16/8's or what have you ... the CPU board is the same for all of them, had two card edge slots near the left side. There were only 4 cards for Xerox 820's made in the USA. Two of them were for the left card connector and two of them were for the right. In all cases, when I say right and left, it will be as if I was looking into the machine from the rear. The left slot is for the drive controller. It will contain either a floppy controller card (works with both 5.25" or 8" drives), a hard drive interface card (8" drives only), or NO board if it's a 16/8 machine with a DEM (Disk Expansion Module). Off the top of my head, the hard drive card is maybe 3" tall, while the floppy controller is maybe 4" tall. NEVER connect the floppy controller card to a hard drive, as you will blow the floppy/hard drive controller board down the line. I do not think connecting a hard drive interface board with floppy's will cause any damage, but I wouldn't chance it. The right slot will contain NO board if it's a standard Xerox 820-II, a 16/8 board if it's a 16/8 (that's an 8086 system on a card, for those of you who do not know), or a DEM buffer board if this is a 16/8 with DEM. Now that I think of it, there was also a 256K memory expansion board for the 16/8, which plugged directly into the 16/8 board. Very hard to find and expensive. I have seen notes where Rank Xerox (in England) may have made some additional cards which went into the DEM. (Note: The DEM has a card cage which can hold 4 or 5 cards, one of which would be the 16/8 card.) There may have been an RX memory expansion card (256K) for the 16/8, and there may have been an RX fancy video graphics board. The most notable incorrect things I saw was that sombody said the 16/8 board contained an 8088, and that the DEM connected up to the 16/8 board. ~ Mike (Sprague.Wbst311@Xerox.Com)
max@mthvax.cs.miami.edu (Max Southall) (10/28/90)
There were a number of third-party controllers for the Xerox 820-II made as well, which used easier to find/cheaper components than Xerox supplied. This arose because of the large number of 820-II boards on the surplus market that needed the controller cards which weren't available. Some of these are still available at reasonable cost or even as build-it-yourself. For the 820-I and 820-II, there are also hard disk SASI adapter cards that plug into the parallel port (Z80-PIO ports) allowing use of a SASI/SCSI hard disk controller and appropriate hard drives - ST506, ESDI etc.
Sprague.WBST311@XEROX.COM (10/30/90)
While my message was not clear on this, I was speaking only of cards made by Xerox, not third party. I am quite interested in hearing about third party cards for the Xerox 820-II computers, especially alternate hard drive controllers! If anyone has information on any of them, especially if they can still be purchased, I would love to hear about it. ~ Mike (Sprague.Wbst311@Xerox.Com)
Sprague.Wbst311@XEROX.COM (11/02/90)
I am forwarding this message for a friend. I too am interested in the answer though. ~ Mike (Sprague.Wbst311@Xerox.Com) ---------------------------------------- > There were a number of third-party controllers for the > Xerox 820-II made as well, which used easier to find/cheaper > components than Xerox supplied....For the 820-I and 820-II, > there are also hard disk SASI adapter cards that plug into > the parallel port (Z80-PIO ports) allowing use of a SASI/SCSI > hard disk controller and appropriate hard drives Could someone enlighten me on this market? I'm currently running a BBS with an 820-II and would love to 'downsize' the rigid (currently 8") and increase capacity (currently 10 meg). Thanx, Tom (TGene.Dloslv300@Xerox.Com) ----------------------------------------