Xerox 820-II User manual

This equipment (except the rigid disk drive unit) has been certified to comply with the limits for Class B Computing
Device, pursuant to Subpart J of Part
15 of FCC rules. Only peripherals (computer input/output devices, terminals,
printers, etc.) certified to complywith the Class B limits maybe attached to this computer. Operationwith non-certified
perpherals is likely to result in interference to radio and TV reception.
The Xerox
820-11 generates and uses radio frequency and if not installed and used properly, i.e., in strict accordance
with the manufacturer's instructions, maycause interference to radio and television reception. It has been type tested
and found to complywith the limits for a Class B Computing Device in accordance with the specifications in SubpartJ
ofPart 15 of FCC rules, which are designedto provide reasonable protection against such interferencein a residential
installation.
If this equipment does cause interference to radio or television reception, which can be determined by turning the
equipmentoffand on, you are encouragedtotryto correctthe interference byone
or moreofthe following measures:
• Reorient the receiving antenna.
• Relocate the computer with respect to the receiver.
• Plug the computer into a different outlet so that computer and receiver are on different branch circuits.
Ifnecessary, you may consultXeroxoran experienced radio televisiontechnician foradditional suggestions. You may
find the following booklet prepared by the Federal Communications Commission helpful: "How to Identify and
Resolve Radio-TV Interference Problems". This booklet is available from the U.S. Government Printing Office,
Washington, D.C. 20402, Stock No. 004-000-00345-4.
The rigid diskdrive generates and uses radio frequency energy. If not installed or used properly (in strict accordance
with the instructions provided), this equipment may cause interference to radio communications. It has been tested
andfound to complywith the limitsforClassA computing devicespursuantto SubpartJ ofPart 15 ofFCC Rules, which
are designed to provide reasonable protection against such interference.
Operation of this equipment in a residential area is likely to cause interference, in which case, the user at his own
expense will be required to take whatever measures necessary to correct the interference.
Copyright© 1982, XEROX Corporation. All rights reserved. Xerox® and 820-WM are trademarks of XEROX Corpora-
tion.

TABLE OF CONTENTS
1. Overview ............................................................................... 1
2. Hardware .............................................................................. 5
System Capabilities
Keyboard
Display
Disk Drives
Printers
3. Operation ............................................................................. 18
Installation
Getting Started
Using Software
Diagnostic
Test
4. Technical Aspects ..................................................................... 28
Specifications
Memory Map
Serial and Parallel Interface
System Monitor
Appendix .............................................................................. 34
A-Disk Care
8-Software
C-Non-Xerox Printers
D-Glossary of Terms

ii

1
___________________________________________________ OVERVIEW
THE 820-11 PERSONAL COMPUTER IS THE SOLUTION!
A LOW-COST AFFORDABLE SYSTEM
As your business processing needs increase, so
do your requirements for additional equipment.
The
820-11 Personal Computer gives you an
alternative to single function office equipment. In
one complete package you'll find all the capabili-
ties required to effectively automate your office
routines.
~ ~
TYPEWRITER '" 0 '. .,JI COMPUTER
~~·i-.
~
WORD
PROCESSOR
DATA
TERMINAL
$8000
$6000
$4000
$2000
r[=lil
~
~
I FROM $3000 I
ELECTRONIC DATA DESK TOP WORD
TYPEWRITER TERMINAL COMPUTER PROCESSING
SYSTEM
A MULTI-PURPOSE WORK-STATION
The 820-11 was designed to be multifunctional. It
combines a solid hardware design with a wide
selection of software, thus handling not only your
word processing and typing needs, but also your
information and data processing tasks.
Whether you're a manager or a secretary, the
820-11 has productivityincreasing features that can
work for
yOU!

1
OVERVIEW ________________________ _
A VEHICLE FOR PRODUCTIVITY INCREASE
intoday's hightechnologymarketplace, yourfirm's
productivity is a direct function of your computing
and word processing capability.
LARGE COMPANY ... WITH LARGE OPERATING BUDGET
THE TRADITIONAL WAY
THE "820-11" WAY
One Computer for Individual Computer for
Large Number of Personnel Each Decision-Making Employee
SMALL BUSINESS ... WITH SMALL OPERATING BUDGET
2
THE TRADITIONAL WAY
Desktop Computer
$4,000
Data Terminal
$2,500
Word Processor
$7,500
Typewriter
$ 900
Each System Is Too
Expensive
To Own
THE "820-11" WAY
• Desk Top Computer
• Data Terminal
• Word Processor
• Typewriter .---~
MUlti-Function Capability
At an Affordable Price

1
____________________________________________________ OVERVIEW
A GROWTH ORIENTED SYSTEM
EXTENSIVE SOFTWARE LIBRARY
AVAILABLE
1
I
I
J COMMUNICATIONS
I DATA BASE MANAGEMENT
I FINANCIAL ANALYSIS
LETTER WRITING
As a desktop computer, the 820-11 gives you a cost
effective wayto automate yourdaily
work routines and
manual tasks. The 820-11 uses the popular CP/M® 2.2
Operating System which opens the door to a virtual
warehouse of software packages. You can purchase
software directlyfrom Xerox orfrom othervendors and
software clearing houses. Your sales representative
can provide you with specific information.
©C)
t--
APPLICATIONS ARE USER ORIENTED
Because the 820-11 is a multifunction machine, it can
be used by a multitude of people
in a variety of ways.
The versatility of the
820-11 becomes apparent as you
explore the available system features. The inherent
system capabilities, coupled with the powerful CP/M®
2.2 Operating System, provide the capability to per-
form many tasks previously handled only by relatively
expensive minicomputers. Thus, anyone associated
with the processing of information can find
an applica-
tion and a use for the 820-11.
~
-
~
-
-
SECRETARIAL 7 •
WORD PROCESSOR
~~
• ELECTRONIC TYPEWRITER
• TEXT EDITOR
FINANCIAL /,:~
• ELECTRONIC SPREAD SHEET
rf:';S ) •
AUTOMATED PAYROLL
cm0';
• ACCOUNTS RECEIVABLE
ENGI~~:9
.• ANALYSIS TOOL
• DATA TERMINAL
• DATA BASE SYSTEMS
---
MANAGEMENT:/nil;nn I •
AUTOMATED FORECASTS
• LONG RANGE PLANNING
~,~J
• EXPENSE ACCOUNTS
"~
LAW
m •
OFFICE BILLING
• AUTOMATED FORM
PREPARATION
• LEGAL DATA BASE
ARCHITECTURE
• JOB COSTING
~l"l~=
• CASH RECEIPTS
-•
CASH DISBURSEMENTS
MEDICAL
'f'
• AUTOMATED BILLING
• GENERAL LEDGER
• PATIENT HISTORIES
ETC.
·
·
-----
-
-
CP/M® is a registered trademark of Digital Research Incorporated, Pacific Grove, California.
3

1
OVERVIEW ________________________ _
AMAZINGLY VERSATILE
TAILOR THE SYSTEM TO YOUR NEEDS
Achoice of five diskdrive units and two printers allows you to choose (and pay for) onlythe capabilities you
need. And, you don't need to worry about outgrowing your system! The 820-11 has been carefully designed
to allow
you to increase its capabilites by adding additional software, disk storage and internal memory. An
expansion slot is also provided in the processor for future customization.
CAPABILITY TO CREATE YOUR OWN SOFTWARE
In addition to the extensive library of CP/M programs, the 820-11 has several programming languages
available. The variety of available languages allows
you to choose the most efficient way to write your own
software.
Some of the most common programs written
by business people are forms fill-in and customized reports.
Below is a partial list of the 820-II's programming features. Your sales representative can give a more
complete listing.
CP/M
BASIC
CBASIC
IITM
All of the features and facilities of the CP/M® 2.2 Operating System are available to
you. The CP/M manual provides
all the specific details.The implementation of CP/M
on the 820-11 makes it one of the fastest and most flexible systems available.
Several versions of BASIC are available. BASIC-80, from Microsoft, may
be pur-
chased directly from Xerox.
It meets the ANSI subset standard for BASIC and has
many features not found
in other BASICs. It's available on 51
/4"
and 8" disks.
CBASIC is the Compiler Systems version of BASIC. It's available through Xerox on
5V4" and 8" disks.
CBASIC II ™ is a trademark of Digital Research, Incorporated, Pacific Grove, California.
4

2
__________________________________________________ HARDWARE
THE 820-11 SYSTEM
The 820-11 system is acollection offourcomponentsworking in unison. The componentstructure givesyou
flexibility
in placement and system capability.
KEYBOARD
DISPLAY (CRT)
The keyboard is used to communicatewith the system. The keys are organized
in
standard typewriter style.
Similar to a TV screen, the CRT provides clear readable viewing of the material
being entered. Thedisplaydevice also housesthe computer, which is the heart of
the system.
MEMORY (Disk Drives) Disk drives allow the fastest and most convenient means for storing large
amounts of information.
PRINTER (Optional) The printer provides hard copy output of the information on the screen or disk.
5

2
HARDWARE __________________________________________________ _
6
HARDWARE CAPABILITIES FOR
MOST COMPUTING APPLICATIONS
COMPONENT
...-t.~~~~ '~\
'D~~~~- -:~~~-~c --~I '
111,---- ------....
I :
~~ - ~
DESCRIPTION/CAPACITY
DISPLAY SCREEN
• 24 line display
• 80 characters per line
• Flicker free screen
• White characters on black
screen
• Exceeds industry standards
• Brightness adjustment
PROCESSOR
KEYBOARD
• Standard typewriter key layout
•
10 key numeric pad
• Automatic repeat of most
common characters
TECHNICAL DESCRIPTION
CRT
• 7 x 10 dot matrix for characters
• Software selectable character
attributes
· Inverse video
· Blinking
· Low intensity
· Graphics with 4 x4 Pixel
resolution
• High speed character display
• Single board
Z80A®
Microprocessor
• 4 Mhz clock
• 64K RAM, 6K ROM
• Softloaded
• 820-11 system Bus access
• 2K ROM or RAM expansion
capacity
• 32K RAM expansion capability
via system Bus
• Dual parallel ports
• Dual serial ports
DATA ENTRY CONSOLE
• Standard 96 character ASCII
keyboard
• 4 key cursor control
• Alpha shift lock
• Erasing backspace key
• 32 software definable keys
Z80A is a trademark of Zilog, Inc., with whom the publisher is not associated.

2
____________________________________________________ HARDWARE
DISK DRIVE OPTIONS
COMPONENT DATA STORAGE CAPACITY
51 /4" Single Sided Dual Floppy Single Density Disk holds 40
Disk Drives pages
Double Density Disk holds 70
, 1\1111\\1\\1\\\\ pages
ti I ~ R
u ~[U
\1 '
5V4" Double Sided Dual Floppy Single Density Disk holds 80
Disk Drives pages
\ Double Density Disk holds
140
\ \1\\\\1\1\\\\\\\ pages
@ I ~ ~
U ;~U
\[ I[
8" Single Sided Dual Floppy
Disk Drives
8" Double Sided Dual Floppy
Disk Drives
i
f
\-IT
n1
I
I
8" Rigid Disk Drive
Single Density Disk holds 120
pages
Double Density Disk holds 240
pages
Single Density Disk holds 240
pages
Double Density Disk holds 480
pages
The Rigid Disk holds
up to
4000 pages of material.
DISK PARAMETERS
SINGLE DOUBLE
DENSITY DENSITY
128 256
18 17
40 40
3 3
81K 155K
SINGLE DOUBLE
DENSITY DENSITY
128 256
18 17
80 80
3 3
172K 322K
SINGLE DOUBLE
DENSITY DENSITY
128 256
26
26
77 77
2 2
241 K 482K
SINGLE DOUBLE
DENSITY DENSITY
128 256
26 26
154 154
2 2
490K 980K
Bytes/Sector
SectorslTrack
Tracks/Disk
#Tracks reserved
for system use
Disk capacity
for user
Bytes/Sector
SectorslTrack
Tracks/Disk
#Tracks reserved
for system use
Disk capacity
for user
Bytes/Sector
SectorslTrack
Tracks/Disk
#Tracks reserved
for system use
Disk capacity
for user
Bytes/Sector
SectorslTrack
Tracks/Disk
#Tracks reserved
for system use
Disk capacity
for user
Rigid Disk Parameters
256 Bytes/Sector
32 SectorslTrack
1024 Tracks/Drive
8.19 M-Byte Usable Capacity
f
\- A Double Sided 8" Floppy Disk
Drive
is provided with the 8"
fixed disc drive. Double Sided 8" Floppy DiskDrive
provided for back-up and transfer
Each K of disk capacity
is equal to 1024 characters (bytes).
Each M-Byte of disk capacity
is equal to 1,024,000 characters.
7

2
HARDWARE __________________________________________________ __
PRINTER
Xerox 20 CPS printer
Xerox 40 CPS printer
\'w
( "
Ii
f --
J 0 ow 0\ []I =:l\ J
*P.S. is optional
8
PRINTER OPTIONS
DESCRIPTION/CAPACITY
• 10, 12 or 15 pitch
• 25 characters per second print
speed
• Self homing printwheel
• "Drop-In" print wheel for easy
print wheel changes
• Interchangeable print wheels
• Interchangeable ribbons
• 10, 12 or 15 pitch
• 40 characters per second print
speed
• Interchangeable print wheels
• Interchangeable ribbons
TECHNICAL DESCRIPTION
• Bidirectional printing
• 13 inch line width
• Daisy wheel print element
• 98 character print wheel
• Self test diagnositc print
• Graphics capability
• Bidirectional printing
,.
13 inch line width
• Daisy wheel print element
• Choice of tractor or friction
feed
• Graphics capability
• 98 character character set

2
___________________________________________________ HARDWARE
GENERAL
PROCESSOR
RANDOM ACCESS
MEMORY (RAM)
VIDEO DISPLAY
KEYBOARD
DISK DRIVES
A TECHNICAL VIEW
The modulardesign ofthe 820-11 system enhancesthe flexibility provided by
the CP/M Operating System. The combination ofoperations provided bythe
system makes it one of the most adaptable on the market. This flexibility
allows the system to be tailored to the needs of each user.
The processor is softloaded and uses a Z80-A based microprocessoroper-
ating on a 4 megahertz clock, with 64K RAM and 6K ROM memory. The
system monitorcontrols the essential functions of initializing and controlling
all system input/output resources, and also provides commands that can be
used to assist in programming. (Details on page 32.)
Three undedicated ports are standard on the
820-11: two serial ports are
located at the back of the display unit, and an additional dual parallel port is
located inside thedisplayunit. These allowprinters, communication devices
and otherperipheral equipmentto be interfaced with the system. (Details on
page 30 and 31.)
The
820-11 system comes complete with 64K RAM. Up to 56K is user
definable resulting in a great range of possible applications, from writing a
letter to complex scientific calculations. (Details on page 29.)
The 24 line, 80 character display exceeds industry standards for desk top
computers, and equals industry standards for small word processing sys-
tems. Easy viewing of the 7 x1 0 dot matrix white on black characters is
enhanced by an adjustable brightness and high quality flicker free display
screen. A 4 x 4 pixel resolution graphics capability allows graphics displays.
The Xerox
820-11 uses a standard 96 character ASCII keyboard. Additional
keys are conveniently located to the right of the keyboard. A cursor control
provideseasyaccessto anypointon the screen. A
10 keynumerickey pad is
included for convenience and speed in typing statistical material. The 820-11
provides for 32 of the keys to be software definable.
The choice of five disk drive options allows you to configure the system to
your needs. The
5114" Dual Floppy Disk Drives can store up to 81 K oftyped
material per side at single density, or twice that at double density. The 8"
Dual Floppy Disk Drives can store 241 K of typed material per side at single
density, or twice that at double density.
Thefloppydisks aresoftsectored and when initializedwill have40 tracks per
side on the 5114" diskand 77 tracks perdisk on the 8"disk. For large amounts
of data storage, the 8" rigid disk drive offers 8.2 M-bytes of usable storage,
with a double sided floppy 8" disk for back up and data portability.
9

2
HARDWARE ____________________________________________ ~ __ ___
THE 820-11 KEYBOARD
CONVENIENT BY DESIGN
The 820-11 keyboard has been designed for operator convenience. The keyboard is divided into two
sections, a standard typewriter style section, and a special functions section.
The standard typewriter keyboard allows those with previous typing experienceto rapidly become familiar
with the
820-11 system. Standard typing key functions are maintained (space, return, etc.) while other keys
are enhanced or added to provide access to special features.
•
IMkl'
10
The HELP key is a uniquefeature ofthe 820-11 system, and it's appearance on the
keyboard demonstrates Xerox's commitment to making this a truly "friendly"
system. Pressing the HELP keytells the 820-11 word processorthatyou would like
more information.
A
TAB key is provided to allow easy formatting of documents and tables.
The ALPHA LOCK key locks only the alphabetical keys thus allowing you to type
upper case letters and numbers at the same time.
Type
in a wrong character? Just press BACKSPACE and it's gone! Then press
the desired character.
The CTRL keys located on eitherside ofthe space bar allow almost every
keyon
the board to have a second or even a third meaning. The CTRL key is used in
conjunction with the alphabetic keys to input standard ASCII codes.

2
---------------------------------------- ____________ HARDWARE
SPECIAL FUNCTION KEYS
The special function key pad to the right of the standard keyboard provides additional keys for special
applications, without cluttering up the standard typewriter layout.
•••••
------ •• g~.
,..------- ••• ~ •
••• iiI.
'-------~--~,
Several special function keys have been grouped in this section for your convenience.
•
•
••
• &1
••
Similar to the backspace key in nature, the DELete key erases while moving the
cursor to the right. This feature makes corrections
in the word processor mode
very simple.
The ESCape key is used forsending special commandsto the system in both the
word processor and CP/M modes.
The LINE FEED keyis used to advancethe paperwithouttyping a carrierreturn. It
also performs specific functions
in some programming languages.
These keys are primarily used with the numeric key pad while entering statistical
data. Many accounting packages allow you to use these keys as debitand credit
keys.
Cursor control keys allow the cursor to be positioned at any point on the display
screen, so you can go directly to the point at which a revision is to be made.
11

2
HARDWARE ________________________________________________ __
FLICKER FREE DISPLAY
Thequalityflicker free screen selected forthe 820-11 provides easyviewing forthe operator. The 24 line, 80
characterdisplay is equal to the industry standard for low cost word processors, and exceeds the industry
standardsfordesktopcomputers. Thedisplayunitforthe XEROX
820-11 alsocontainsthe processorforthe
systemwhich issoftloaded and usestheZ80Abased microprocessorwith 64K RAM memoryand
6K ROM.
BRIGHTNESS
CONTROL
ON/OFF SWITCH
BRIGHTNESS CONTROL
RESET BUTTON
12
RESET BUTTON
Conveniently located out of the way under the edge of the right side
panel, this switch controls power for the display and the central
processor. Its location prevents accidental power turn off.
The intensityof the displaycan be adjusted bythe brightness control
located underthe edge of the left side panel. The control allows you
to adjust screen intensity for maximum clarity and comfort.
The reset button, positioned at the rear of the unit is used for reini-
tializing the softloaded operating system when changing operating
modes. Pressing this button tells the
820-11 you want to start over
(boot).

2
__________________________________________________ HARDWARE
VERSATILE INPUT/OUTPUT PORTS
The standard 820-11 system is equipped with six ports for input and output. Four ofthe ports are located on
the backofthe display unit, as shown below.
Two ofthe four ports are used for the standard keyboard and
disk drive system components. The fifth and sixth ports are located inside the display unit. (Detailed
information on port assignments is given on pages 30 and 31.)
DISK DRIVE
KEYBOARD
PRINTER
COMM
PARALLEL PORTS
EXPANSION SLOT
DISC DRIVES
KEYBOARD PRINTER
COMM
DISC DRIVES
KEYBOARD PRINTER
OISC ~IYU ... n.o .... o ''''NHII co....
DISC DI"'IU IIl(Y'OAIIlO PIIIINTI" • co ....
Used for connection of either the 8" or the 5V4" Dual Floppy disk drives, or
the 8" Rigid Disk Drive.
Used for connection of the keyboard, which is where data is input.
A serial printer can be connected to this standard RS-232 port.
This port can be used forstandard RS-232 communications input/outputvia
a modem.
The dual parallel port inside the display cabinet is provided for the conveni-
ence of users who wish to use a parallel printerorother parallel input/output
devices. '
The expansion slot inside the display cabinet provides all of the Z80-A
control signals for connection to custom devices for future expansion.
13

2
HARDWARE __________________________________________________ _
CHOICE OF DISK DRIVES
The 820-11 systemcomesoptionallyconfigured with 5V4" or8" Dual Floppy, or8" Rigid Disk Drives. Thedisk
drives offer high data storage capacity, fast data retrieval, and allow datato be accessed in random order.
(See page
17 for more information.)
8" Dual Floppy Disk
Drive 8" Rigid
5V4" Dual Floppy
Disk Drive
~
1\
~
~
~
1\
' ..
~~
n n
~~
B
~
-
~
J
~
~
The floppy disk drives are very similar in operation, but differ in physical appearance. The following
paragraphs describe how disks are inserted into the drives.
• The 5V4" drive is opened by pulling on the left edge of the latch which is over the drive
opening. Once adiskis inserted into the drive, the latch is closed by pushing the leftside of
the latch until it clicks into place.
• The 8" floppy disk drive is opened by pressing on the oblong button
be·side the diskdoor.
There is a small red light on the oblong button.
To close the door, pull the doorto the left
until it latches. This procedure is the same for the 8" floppy diskdrive which accompanies
the 8" rigid disk drive.
When purchasing disks, specify:
5V4" 40 track, soft sectored floppy disk, double density certified
8" 77 track, soft sectored floppy disk, double density certified
If your 820-11 disk drive is double-sided, be sure you purchase disks that are certified for use in double-
sided drives.
14
J

2
____________________________________________________ HARDWARE
FLOPPY DISK STORAGE
The disks are similar in looks and operation to a phonograph
record. They are thin and flexible (hence the name Floppy
Disks) and are sealed in astiffpaperjacket. The paperjacket
covering the disks permit them to be handled with relatively
few precautions.
The disks have a write protect tape which can be used to
protect against accidental loss of data by overwriting.
The disks are placed
in the disk drives, and as information is
to be stored or retrieved, they are rotated at high speed. A
read/write head (similarto a tape recorder) is moved radially
along the head access slot, and can be positioned over any
portion of the rotating disk.
Index
Hole
Head Access Slot
Paper Jacket
Tracks
Write Protect
Tape
Sector
Before the 820-11 can use a disk, it must format (initialize) it. The format of the disk allows the 820-11 to
quickly find and retrieve data from the disk.
When a disk is formatted (initialized), it
is partitioned into tracks as illustrated above. Each track is divided
into pie shaped wedges, called sectors. Thisarrangementallows each segment ofthe diskto be referred to
by sector and track. Just like the needle and tone arm of a phonograph turntable, the read/write head can
be placed over any track, without having to read (play) intermediate tracks. This random access feature
allows rapid access to the data stored on the disk.
Double sided disk drives allow information to be stored on both sides of the disk, just like the two sides of a
phonograph record.
Double densitydisk storage refers to a means by which the drive may store up to twice the information on
the same amount of space on a disk.
15

2
HARDWARE ________________________________________________ ___
RIGID DISK STORAGE
A rigiQ disk can store much larger volumes of information
than noppy disks. And physical structure and speed of the
rigid disk gives you significantly faster data transfer rates.
The recording ofdata onto and retrieval of information from a
rigid disk is very similar to the process for a floppy disk. The
maindifferences arethatthe rigid diskis made
up oftwo hard
surfaceplattersand hasfour read/write
heads-one for each
side of the two platters, as shown
in the illustration to the
right.
An
8" floppy disk drive is included with the rigid disk drive unit to provide compatability (read a disk from
another
820-11 and read software programs purchased on floppy disks). In addition, the 8" floppy disk can
be usedto makebackup copies ofthe information stored on the rigid to guard against accidental dataloss.
When the rigid disk is initialized (formatted), it is divided into
sectors and tracks much like the floppy disk. Each platter of
the rigid diskwill have
256 tracks and each trackwill have 32
sectors. Each of the sectors can hold 256 characters, so the
entire disk can hold over 8 million characters.
You could usethe diskas onebig 8 million character disk. Oryou could dividethediskinto segments sothat
you can store letters in one segment, a lengthy database
in anothersegment, all your programs in a third,
etc.
The 820-11 will automatically divide the disk into four segments (called partitions) containing 4 million
characters, 2 million characters and two segments of 1million characters each. If this partitioning does not
meet your needs (perhaps you have a data base larger than 4 million characters), you can change the
partitions using the CONFIGUR program provided by Xerox. See your Reference Manual for details.
The four positions are referred
to as
E, F, G and H.
16