website/content/museum/xerox-8-16.md

---
title: Xerox 8 / 16
categories:
- Computers
types:
- Professional Computer
origins:
- U.S.A.
years:
- '1983'
cpus:
- Zilog Z80A @ 4 Mhz
params:
  name: 8 / 16
  image: /media/museum/photos/xerox_8-16_2.jpg
  company: /companies/xerox
  company_name: Xerox
  specs:
  - label: NAME
    value: 8 / 16
  - label: MANUFACTURER
    value: Xerox
  - label: TYPE
    value: Professional Computer
  - label: ORIGIN
    value: U.S.A.
  - label: YEAR
    value: '1983'
  - label: END OF PRODUCTION
    value: '1985'
  - label: KEYBOARD
    value: Full-stroke keyboard with numeric and editing keypads, arrow keys, 12 function keys
  - label: CPU
    value: |-
      Zilog Z80A @ 4 Mhz (8-bit)\
      8086 @ 4,77 Mhz (16-bit)
  - label: SPEED
    value: 4 Mhz (Z80A) and 4,77 Mhz (8086)
  - label: RAM
    value: 64 KB (Z80) + 128 KB (8086)
  - label: ROM
    value: 4 KB Bootstrap
  - label: TEXT MODES
    value: 80 x 25 / 40 x 25
  - label: GRAPHIC MODES
    value: 640 x 256
  - label: COLORS
    value: Unknown
  - label: SOUND
    value: Beeper
  - label: I/O PORTS
    value: Serial 9600 bauds, Internal Expansion Slot, External Floppy Connector
  - label: BUILT IN MEDIA
    value: One or Two 5.25'' or 8'' disk-drives
  - label: OS
    value: CP/M (8bit), CP/M 86 (16bit, MSDOS optional)
  - label: POWER SUPPLY
    value: PSU built-in
  - label: PERIPHERALS
    value: Memory expansion, Graphical board, printer, hard-disk, mouse
  - label: PRICE
    value: from 4575 to 8390 (France, 1984)
  tabs:
  - photos
  - adverts
  photos:
  - title: COMPLETE SYSTEM
    subtitle: ''
    text: ''
    image: /media/museum/photos/xerox_16-8_1.jpg
  - title: BOOT SCREENSHOT
    subtitle: ''
    text: Thanks to chrism3667 for the picture
    image: /media/museum/photos/xerox_8-16_boot.jpg
  adverts:
  - title: FRENCH ADVERT
    subtitle: ''
    text: |-
      "You hesitate between two standards."\
      "Rank Xerox doesn't."
    image: /media/museum/pubs/xerox_16-8_pub_1.jpg
  comments:
  - author: Kyle Count (New Hampshire, USA)
    date: Sunday 9th April 2023
    text: We had one of these when I was a kid growing up. Don''t remember much, except the keyboard that came with it was awful! Very, very flat, mushy keys...
  - author: Jay (Washington State USA)
    date: Tuesday 22nd September 2020
    text: |-
      I am looking for one of these at a cheap price, I will pay up to 100$ including shipping if I have to pay for it\
      Email is jaya.buckwheat@gmail.com
  - author: Colin Barker (United Kingdom)
    date: Sunday 17th November 2019
    text: As a working technology journalist I got a 16/8 to test and then write about. The ability to be able to swap between MSDOS and CP/M at will was great. It as an elegant system and came with a cool Xerox printer. I gave it an OK review but argued that people would use either CP/M or MSDOS but not both. The nice people at Xerox never asked for it back so I wrote all my copy on it for the next four years - lucky me!
  - author: James Bell (Austin, Texas)
    date: Sunday 23rd July 2017
    text: |-
      Worked for Balcones Computer Corporation with Robert Burns (the MicroManiac) and brother Jay Bell.\
      Balcones Consulted for Xerox and took the Xerox 820 from I to Xerox 820-II. If you look through the BIOS code documentation you''ll see references to Balcones. Balcones drove adding the expansion connector and developed the 16/8 CPU card for Xerox. The expansion chassis used a WD1002 controller to interface the external floppy and hard disk (same type of controller used in the Kaypro 10)...both Kaypro and Xerox 820 were derived from the "Big Board". Our first prototypes of the 16/8 CPU card was created using a "multiwire" connection method, but production versions were multilayer printed circuit boards. I still have at least one of the multiwire prototypes. Jay Bell always said that the weak link in the 8086 card design was the use of many PAL chips whose timing did not always meet spec and thus created an instability sometimes.\
      Balcones also sold their Accounting System (The Boss System) which was sold by Xerox and Rank Xerox worldwide. A lawsuit relating to Xerox royalties for various projects ended up taking Balcones down. Many of Balcones employees transitioned to PC''s Ltd (later called Dell) where Jay Bell and Robert Burns designed the first 286 system for PC''s Ltd which was Michael Dell''s first in house Computer design.
  - author: Pete Martin (UK)
    date: Saturday 30th May 2015
    text: |-
      I worked for Xerox in the UK during the eighties and sold loads of the 820 and 16 / 8 machines. The way the 16 bit part worked was to convert everything to 8 bit, do the processing, and convert it back. I remember a customer buying 820''s and later on the PA wanting her own machine, so I sold her a 16 / 8 with 16 bit programs. Compared with the 8 bit systems it ran at half the speed!\
      The main advantage of the Xerox system was the software, which in reality was the predecessor of microsoft office - spreadsheets, word processing, database. It was this that customers bought - the actual computer was mostly irrelevant - as long as it was reliable.\
      The 16 / 8 was due to be replaced with the a new computer which was a re-branded Olivetti, code named M24 I think. I remember being on a course training on it and it was fabulous. At the end of the course HQ sent word out that it had been cancelled! It was thought that desktop computers were the wrong direction to take.\
      Xerox invented the mouse, laser printers, network software, office software, and much more 15 years before anyone else and totally failed to see the potential!
  - author: Arun Baheti (Los Angeles, CA, USA)
    date: Wednesday 23rd October 2013
    text: I still miss my 16/8. The low profile keyboard is still the best I''ve ever used. I ran a BBS for several years, and used mine all the way through college (I started with an 820-I, upgraded the board to -II, then to 16/8, all with 8" drives and rigid drive, and eventually to the slimmed down 16/8 which was 5.25"). I had some add-on hardware such as a mouse and Ethernet adapter "box" that was nearly the size of the slim-16/8 main box. The machine taught me everything about computers, networking, and programming. Reliable and sturdy, a real friend. I still have the original manuals, tech manuals, and boxes of disks that I couldn''t bring myself to part with. $Arun Baheti
  - author: enrico lazzerini (pisa (italy))
    date: Sunday 28th April 2013
    text: 'i was studying xerox 820-II interface cards, so i met xerox 16/8 description in my italian language with those important pictures of the EM. These are here : http://www.1000bit.it/support/articoli/xerox/xerox16_8.pdf it would be so nice to find almost its schematics on Internet. Regards Enrico - Pisa (Italy)'
  - author: Joe K
    date: Saturday 3rd July 2010
    text: 16/8 got me through college, though I almost missed deadline on a final when my diabolo 630 crashed with only 20 minutes before the deadline. Got it up and running 10 minutes before the deadline but had to print 11 pages - and it printed a page per minute! Ran in with my paper 5 minutes after the deadline, but the proctors let it slide!
  - author: Mnem (Canada)
    date: Friday 16th December 2005
    text: Heh, I always wondered which system these disk drives matched. I have two of the external dual-8" floppy units. They're heavy as heck, but they make good foot stools.
  oc_id: 14
  source:
    url: https://web.archive.org/web/20230413210528/http://www.old-computers.com/museum/computer.asp?c=14
    date: '2023-04-13'
---

The "best of both worlds". The Xerox 8 / 16 belongs to a family which appeared at the end of the 8 bit era, when MS-DOS began to be a standard for the 16-bit systems. It has two CPUs, the Z80 allows the use of CP/M and the 8086 is for MS DOS and CP/M 86. This computer was actually two computers sharing certain resources, like the display, the power supply and the floppies but essentially seperate.\
This computer was one of the first, if not the first PC-sized computer that had concurrent processing (not time share, but real honest to goodness concurrent processing). One could start a task on either operating system, say a spread sheet, and then hot key over to the other processor and perform another task, all while the other "side" was working at full speed at it's task. Because the 16/8 was actually two computers in one, both sides worked at full capacity and did not share ram or other system resources required for processing data: they worked at full speed regardless of whether or not the other side was in use. Only the "active side" had access to the video, floppies and the hard drive (if avaialble), but with dual floppies, one floppy could be assigned for the 8 bit side and one for the 16 bit side. In that instance, each side would access the its assigned floppy when brought to the active side.

The 16/8 is made of four units :\
\- a 12'' monochrom monitor, housing the whole hardware of the system, like in the Apple Macintosh,\
\- the keyboard, very complete,\
\- the disks (two 5''1/4 disks, a hard-disk (5 MB, later 10 MB) was optional),\
\- an expansion box meant to house the different expansion boards.

There was also a Diablo printer in option. The whole system thus took quite some room on your desktop!

After the presentation of the first 16/8 in 1983, Xerox launched a new version in 1984, faster, more compact and sold with a hard-disk.

Unfortunately the 16/8 was a bit obsolete as the 8-bit professional systems were dying slowly and the 16/8 wasn't offering much more than an IBM PC launched a few years before. The price of the system wasn't even attractive.\
Xerox stopped the production of all its micro-computers at the start of the year 1985.

This computer is the direct successor of the [Xerox 820 series](/museum/xerox-820/), which could be almost converted into a Xerox 8/16 with a special 8086 board.

**Dale Carpenter** adds:\
Several things, an 820-II has an extra expansion slot on the motherboard. if you put the 16-bit card into that slot your 820-II is now a 16/8.\
Your picture shows a rectangular box called an EM-II (expansion module - II) to add it to a 16/8 you remove the 16-bit card and install it in the card cage in the center of the EM-II then install the card with 2 wide ribbon cables attached(coming from the EM-II) into the expansion slot on the motherboard.\
The EM-II has either 1 hard drive, 1 floppy or 1 of each. The system supported the external drives also, the dual 5.25" and 8" boxes.\
One final note not mentioned: all of the 8" drive boxes had an expansion plug on the back you could daisey chain up to 4 drive units onto any of the 820, 820-II and 16/8 machines.

---

Thanks to chrism3667 for the picture