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xerox 16/8

enrico

Experienced Member
Joined
Nov 4, 2007
Messages
121
Location
Pisa - Italy
Hi all,
I was intrigued on the addon board with cpu 8086 and his daughter with memory expansion for the xerox 820-II. Along with the machine 820-II constituted the xerox 16/8. Manual 610P72384_820-II_Technical_Reference_1984.pdf does not include pages from 121 to 150 in which they were described. I found an old review in Italian here http://www.1000bit.it/support/articoli/xerox/xerox16_8.pdf The seventh and eighth page report cards that made up the expansion module and the card with the No. 2 circled seems to be the card with the 8086. There should be a manual "820-II: 16/8 PC Service Manual 600P 86711 Amendments May 1984" but I could not find it on the net. Someone knows best? Have photos more detailed?
thanks
Enrico
www.vintagesbc.it
 
This thread being Xerox 16/8, I am having documentation problems with a recent 16/8 purchase that came with the Expansion Module (EM-II?...Xerox ID metal chassis tag shows product code is F89). I can find little to none in documentation, so detailing in hopes of expanding the knowledge base.

Assembling the system yields "Rom Error", with failure to initialize (no beep at power on, just this printed error message. Located the error message in the 820-II BIOS code, but that's about all. I suspect the switch settings may be wrong on one of the following cards below. There is a 2732 EPROM inside the EM-II chassis, perhaps an option ROM that is not getting read. Disconnecting one of the cables to the EM-II chassis allows the system to initialize and beep "OK".

This EM-II product had a fairly short life cycle before Xerox backed out of the product line. Mine has multiple problems I need some help with. (Did Xerox ever get to the Documentation phase on this project? Did they release it? Maybe RANK Xerox in Italy, France or the UK?)

-There is the interface card that plugs into the smaller expansion connector of the 820-II board (8086 slot).
*there is an 8 position dip switch at U-3 that I need to verify is set correctly, BUT no schematic or documentation on this card. The card number is 140P83074A
DipSw on my card is set with 8=on, all others=OFF
(This is the card that the 2 long cables plug into that interface to the rear of the EM-II chassis. The bus connector on the
main CPU card is the same one that the 8086 card would plug into).

-There is no schematic found of the circuit card inside the EM-II chassis that the cables plug into.
*There is yet another DIP switch on this circuit card that the cables interface to...need to verify settings.
(My DipSw at U14 is set switches 3 and 8 = ON, all the rest=OFF)
(Board number = 140P83147A) This board also contains a PAL or 2, a 2732 EPROM, a 40 pin SASI interface, a 50 pin
header (?), header to interface to a 5 slot bus that the 8086 plugs into.

-My Shugart model 712 ST-506 HD (11Mb) powers up, then powers off squealing.

The disk controller is a stand alone 5.25" form factor WD 1002-05G capable in hardware of supporting 3 st-506 drives and 2-4 floppy drives (probably 2).

I have seen descriptions of 1HD+1FLoppy, but not a 2 Floppy setup (there is only room for 2 half height devices in the alloted space in the drive bay). FYI, My floppy is a Shugart SA455-3AA, DS/DD (verified works on an IBM XT.) (Will verify the WD Disk controller works on a Kaypro 10).

Questions I seek to answer:

-What is that 50 pin header for on the EM-II board?

-Will the BIOS actually support more than one ST-506 device connected to the WD1002-05G controller board?
(Chassis ribbon cable openings on the back of the chassis)

-How many floppies can be supported via the WD controller? 1,2,4?

-What other cards were developed for adding into the 8086 5-slot bus?

-Is the ROM code for the EM-II circuit board archived somewhere so I can check the checksum on the one I have?

-There are 2 10-pin headers on the cable card that plugs into the CPU box 8086 slot (the ribbon cable card). J3 and J4.
What is their purpose?

-With the 5.25" floppy residing in the EM-II chassis, will the standard 820-II floppy controller card with 1797 floppy controller chip driving dual 8" drives still work with the EM-II?


Unrelated to the EM-II (but not totally off topic):
Anyone have an elegant ram upgrade daughter card for the Xerox 8086 CPU card? A Xerox version or an adaptation, or am I looking at wire-wrapping up a plug-in 128K memory card?

Any help or comments are appreciated.
 
Enrico,

I think those pages you are looking for are in a different archive. It is available at Bitsavers:

search for:
pdf > xerox > 820-II > 9R80758_Xerox_Professional_Computer_Technical_Reference_1984.pdf

Nothing on the EM-II setup, but is does have etch1, etch2 and 8086 CPU card, Floppy and HD/SASI disk drive cards.

This is the latest Technical Reference release I have found to date for Xerox 820-II.
 
Well,
the document 9R80758_Xerox_Professional_Computer_Technical_Reference_1984.pdf seems to be more complete including the schematics of etch1, etch2 and 8086 CPU card, Floppy and HD/SASI disk drive cards.
Thank so much. I haven't it before (something they seems all much similar...)

xBCC_Mechanic : May you attach pics of each card you have?

Thanks
Enrico
 
Well, there was quite a bit of rust scattered about the cabinet and I wanted to take some pictures of the EM-II cabinet, so in the process of taking the pictures I stumbled upon the root cause of the ROM ERROR message I was getting. There was a bent over connection pin of the J1 connector. Not sure what that pin is or does, but probably a data or address line. Upon trying to straighten the pin it broke off, but I happened to have a replacement AMP connector and replaced the 50-pin J1 of the EM-II Board.

All works now...just need to source a replacement ST-506 drive, but using 2 SA455 drives for now. Booted up MSDOS 2.0 and backed up the MSDOS Master diskettes.

First time posting a picture here...Enrico, more pictures to follow. (I am actually surprised at how little information on the 16/8 exists on these forum pages...)

Xerox_EM_II 039.jpg
 
Thanks for the precious pics. it is not easy to have them. I never fiund them before on internet.

I tried to analyze the schematics section in the manual 9R80758_Xerox_Professional_Computer_Technical_Reference_1984 and i wish to try to define it and hoping it will be useful, with the help of more experienced, can be integrated. Maybe that way you will be able to find the missing part of the layout of xerox 16/8 and of its expansion module.

From pages 109 to 116 are the diagrams of the Xerox 820-II first version (I mean for the first version that does NOT contain the chips U101 and U102 on the xerox 820-II mainboard).

From pages 117 to 124 are the diagrams of the Xerox 820-II second version (I mean for the first version that does contain the chips U101 and U102 on the xerox 820-II mainboard).

Pages 125 and 126 show the schematic of the Floppy Disk controller card that was inserted into J12 (72 pin card edge female connector) on the main board when the devices were only floppy disk drive.

Page 127 gives a schematic diagram of the SASI controller card that was inserted into J12 (72 pin card edge female connector) on the main board between devices when there was almost an hard disk with its SASI board.

From page 128 to page 131 shows the layout of the card with the CPU 8086, the eprom 2716, the static RAM, and 64k +64 k DRAM. The card has a card edge connector male 50-pin, a 50-pin IDC connector and a connector with 3 rows of 32 pins of which used only the outer rows (1 to 32 and 65 to 96). The latter seems essential to bring the signals to an expansion card for additional memory, perhaps as a daughter card is inserted?

Page 132 gives a schematic diagram of the memory expansion to 128KB.

I think I read that without the expansion module, the card with the 8086 cpu was inserted directly into J11 the 50-pin slot of the xerox 820-II mainboard and that on this card it was directly insert a memory expansion.

With other supports will be fine to rebuild all possible on these boards and the 16/8 xerox also.

Enrico
 
Enrico, Thanks for the review.

The following link to bitsavers Appears to be the correct WD controller document for the controller used in the Xerox F89 (EM-II) chassis of the Xerox 16/8. The capabilities of the card differ from the one used in the Kaypro 10 in that this one is fully populated with all the floppy chips. This WD 8"x 5" stand alone controller is capable of controlling 3 ST-506 devices and 4 SA450 type 5.25" devices....again, the system BIOS may not be setup to utilize this capability.

http://http://ia801606.us.archive.org/18/items/bitsavers_westernDig030WD100205HDOOEMManualJul83_3035382/61-031050-0030_WD1002-05_HDO_OEM_Manual_Jul83.pdf
 
Enrico,

This is a great asset.

This isn't exactly the Xerox Technical Reference manual I had hoped to locate, but it is a great find and fills in a lot of blank spaces and answers many questions. Note that they only got 3 issues of the Newsletter sent before the project was cancelled...
 
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