Radio Shack TRS-80 III User manual

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lIa«llo/haeK
TRS-SO @) ModelII
Operation Manual
A Guide to Using the Computer:
Connection, Power-Up and Operation
CUSTOM MANUFACTURED IN THE U.S.A. BY RADIO SHACK ~ ADIVISION OF TANDY CORPORATION

-.-
Contents
1. Brief description of basic system 5
2. Installation , 8
3. Operation , .. , 10
Turning the Computer on
Using the RESET switch
Inserting aDiskette
Removing aDiskette
Loading the Operating System
Keyboard Operation
Video Display Adjustment
4. Power-Up Diagnostic Messages 17
5. Care and Maintenance , 19
Care of Diskettes
Tips on Labeling Diskettes
6. Add-Ons , 21
Additional RAM
Additional drives
Peripherals
Other boards
7. Specifications , .. , .. , , 25
Display Character Set
Power Supply
Floppy Disk Drive
Serial Interface Signals and Levels
Parallel Interface Signals and Levels
3

.--.. .. ,.-
j1/ Brief Description of ,System
The Radio ShackTRS-80 Model II is adisk-based computer system
consisting
of two majorcomponents:
• a Display Console with built-in disk drive
• a separate Keyboard Enclosure
The Operating System software is loaded from diskette by abuilt-in
"bootstrap" program.
Here is abriefdescription of the functional elements of the Computer.
Processor
At the heart of the Computer is aZ-80A microprocessor operating at its
maximum design speed (4 million machine-cycles per second).
The processor receives power-up and reset instructions from read-only
memory (ROM). After the TRSDOS initialization program is loaded from
disk, this
ROM is electronicallyswitchedout of thesystem and replaced with
random access memory (RAM).
Random Access Memory (RAM)
The basicsystemincludes 32K bytes of randomaccess memory. (lK =1024.)
An additional32Kbytescanbeadded, for atotal of 64K bytes of addressable
RAM.
Video Display
The Video Display has its own LSI controller chip, to free the Z-80A
processor from display refresh and related tasks.
The Displayofferstwo modes: 80 charactersby24 lines, and40 charactersby
24 lines.
The displayable character set includes the full ASCII set (upper and
lower case alphabet, numbers, and special symbols), plus
32 graphics
characters.
Each charactercan be displayed as white on black or black on
white. SeeDisplayable Characters in Section 7.
5

MODEL II OPERATION
Keyboard
The ModelIIKeyboard has its ownLSI controllertofree the Z-80A processor
from keyboardscan and related tasks.
The Keyboard is in aseparatecase and
is connectedto
the DisplayConsolevia abuilt-incable atthebottomfront of
the Console.
The Model II has the standard typewriter keys (letters, numbers and
punctuation symbols); however, each
ofthese keys can output several
different codes to the Computer, depending on which mode the Keyboard
is
in: Unshift, Shift, Caps, or Control. In addition, the Keyboard features a
Repeat key and two programmable "function" keys. (See Keyboard
Operation.)
Floppy Disk Drive
The Model II includes abuilt-in 8" disk drive. Up to 3more drives can be
added in an externalExpansion Unit. (See Section6, Add-Oos.) Because of a
special high-density recording technique, each diskette can contain 509,184
bytes
of information, which is more than 5times the capacity of a5-1/4"
diskette.
(It wouldtake a 70 wpm typist24 hours of typing atspeedto fill an 8"
diskette.)
Note: Actual space available to user is determined by the Operating System.
The "SystemDrive" (the one that's built-in) must always contain an Operating
System diskette.
The other optional drives can de devoted exclusively to the
storage
of user programs and data. (See the Disk Operating System Manual
for actual diskette space allocation.)
Peripheral Interfaces
There are four interface connections on the back of the Display Console:
•Two serial (RS-232-C) Input/Output (I/O) channels
• A parallel
I/O channel, e.g., for connection to TRS-80 standard
parallel-interface line printers
•Floppy-disk
I/O channelfor connection of theModel II Disk Expansion
Unit
The DisplayConsolealso providesconnectorsand slots for future expansion.
(See Section 6, Add-Oos.)
6

BRIEF DESCRIPTION
Keyboard Case
Display Console
Figure 1: TRS-80 Model 11
Power Switch for -
Entire System
Reset -
Press up
to reset
computer
Drive Release bar
Drive Select -
LED-
Lights up
during disk
operation
Floppy Disk
Drive
Keyboard Connector
Cable
(not shown)
7

MODEL II OPERATION
2/Installation
Carefully unpacktheSystem. Remove all packingmaterial andsave it in case
you
ever need to transport the System. Be sure you locate all cables, papers,
diskettes, etc.
Place
the DisplayConsole on thesurfacewhere you'llbeusing theComputer.
The Computer should be near a120 V AC outlet, so that extension cables
won't be necessary. (See Notes on AC Power Sources.)
Notice the cableatthe bottomright
of theDisplayConsole. Plug this into the
jack
on the right rear of the Keyboard Case. (See Figure 2.)
Once connected, the Keyboard Case can be pushed back into the recessed
area at the base of the Display Console, or moved to any convenient place
within 2- 2 1/2 feet
of the Console.
(For connection of additional peripheral equipment, see Section 6, Add-
Ons.)
Connect the female plug on the Power Cord to the back of the Display
Console.
Connect the other end to asource of 120 VAC, 60 Hz. (See
Figure 3.)
Figure 3. Power Cord connectzd to Dis-
play Console Figure
2. Display Console connected to
keyboard.
Note: The powercord has athree-prong safety plug to provide areliable
ground for the system. This ground is very important to the System. If at all
possible, plug it directly into athree-prong socket. Otherwise use a3-to-2
prong adapter and ground the adapter.
8

Notes on AC Power Sources
Computers aresensitive tofluctuations in the powersupply at the wall socket,
from very short-duration (millionths
of asecond) voltage spikes, to
prolongeddrops in current
or voltage. This is rarely aproblemunless you are
operatingin thevicinity
of heavy electricalmachinery. The powersupply may
also
be unstable if some appliance or office machine in the vicinity has a
defective switch which arcs when turned on
or off.
Your TRS-80Model IIcontainsaspecially designed, built-in AC line filter. It
should eliminate all but the most severe interference problems. Should you
still experience power-line interference, you should take some
or all of the
following steps:
•Install bypass/isolation devices to the noisy appliance
•Fix the defective switch
•Install aseparate power line
•Install aspecial line filter designed for use with computers and other
electronic equipment
In severe conditions, all actions may be required.
Power line problems are rare and many times can be prevented by proper
choice
of installation location. The more complex the system and the more
serious
the application, the more consideration you should give to providing
an ideal power-source for your Computer.
9

-MODEL II OPERATION
3/Operation
1. Be sure all drives in the System are empty, and all
components are turned off. If no Disk Expansion
System is present, be sure to connect the Disk
Terminator plug to the Computer.
2. Turn on the Computer (Display Console). Wait until
the message "INSERT DISKEITE" appears on the
display.
Ifthe message fails to appear within 10
seconds, press RESET. If it stilI fails to appear, turn
the Computer off and check all connections. Wait at
least 15 seconds before starting over at step 1.
3. When "INSERT DISKETTE" is displayed, turn on
the Disk Expansion System (if connected) and all
other peripherals.
4. Insert the System diskette into drive 0 and close the
drive door. The Computer will load the operating
system
and prompt you to enter the date and time.
5.
Before turning the Computer off, remove alI
diskettes from alI drives. Then turn off the entire
system.
6.
After any power-down, wait at least 15 seconds
before turning the System on again. Start at step 1.
Using the RESET Switch
If you should ever lose Keyboard control of theSystem, or you simply want to
re-initialize, press
RESET upmomentarily and release it. The Computer will
repeat the power-up sequence, but the contents of user memory will not be
affected.
Note:
You do not need to remove the diskette during this Reset sequence.
10

OPERATION
Notes on Diskettes
Diskettesare precision recording media. Handle them carefully, as described
under Section5, CareandMaintenance. Be sure you don'ttouch theexposed
diskette surfaces.
Before inserting the diskette, check the write protect notch. (See
illustration.)
If you do not want to write to that diskette, it is agood idea to
leave it "write-protected". This way, the Operating System will
notlet you
accidentally write to that diskette. To write-protect adiskette, just leave the
write-protect notch UNcovered.
(See Figure 4.)
If you do want to write to the diskette, cover the write protect notch with
gummed-foil tape provided with the diskette.
Leave Uncovered
for Write-Protection
Read/Write
Notch
Figure 4. Adiskette and awrite-protected diskette.
Note: Any alteration of the data on the diskette -even the deletion of data
or programs, requires that the diskette not be write-protected. (Cover the
notch with gummed foil tape.)
Inserting aDiskette
1. If the drive door is closed, openit by pressing the release baruntil the door
springs open. (Refer toFigure 5.)
2. Remove the Operating System diskette from its storage envelope. Grasp
the labelsidewith the labelfacing away from the Display and insertit into
the drive slot (see photo).
3.
Gently push the diskette all the way into the slot.
4. Close the door by moving it toward the left until it clicks into place. Some
pressure may be required.
11

MODEL II OPERATION
Removing adiskette
Never remove adiskette while the Drive Select light is on, or while adisk file
is Open.
PresstheDrive Release Bar.The door will openandthe diskette will bepartly
ejected. Carefully remove it, taking care that the shiny diskette surface
doesn't touch the chassis or drive door on the way out.
Note: Once adiskette has been seated in the drive, you must shut the drive
door before you can remove the diskette.
Figure 5. Inserting adiskette (Label might extend vertically across the diskette).
Loading the Operating System
When the Computer promptsyou to INSERTDISKETIE, carefullyinsert the
Operating System diskette into the drive.
As soon as you close the drive door, the Computer will begin the Operating
System bootstrap.
(If nothing happens when you close the drive door, the diskette is probably
inserted incorrectly. Remove it and re-insert it correctly.)
The Computer will then execute adignostic program before starting the
Operating System. This lets you verify that the entire system is in working
order -before you attempt any data processing.
After Completing the Diagnostic Program, the Computer will load the
Operating System. See theOperating System Manual for details.
12
~\

MODEL II OPERATION
Keyboard Operation
The Keys can be divided into four functional groups: Alphanumerics, Mode-
Select, Numeric Keypad, and Control Keys, as illustrated below:
Alphanumeric -
just like a
typewriter
Figure 6. Functionalgroups of Model II keyboard.
Repeat Key Numeric Keypad -
for skilled
1O-key operators
You use the alphanumeric keys just as you would on anormal typewriter.
However, each of these keys cansendmore than one character or codeto the
Computer, depending on which mode you've selected.
13

MODEL II OPERATION
Keyboard Modes
The table below describes the typical use of the various modes. This use is
determined by the Operating System or by the program currently in
execution.
Unsmft -Lets you input lower case letters, numbers
and unshift punctuation symbols.
Shift -Lets you input capital letters and shift punctua-
tion symbols. Hold down while pressing the
desired key, or press the key once so the red
light comes on; while that light is on the Keyboard will
output only Shifted characters. To return to the Unshift
mode, press again.
Caps-Press the key once and the red light will
come on. Typically, in the Caps mode, the alphabet keys
A-Z send capital-lettercodes only, and all otherkeys are
unaffected. To return to the Unshift mode press ~
once so the red light goes off.
Control - Hold down the key while pressing
one of the alphanumerics; this will output the "control"
code assigned to that key.
Note: The Shift mode over-rides the Caps mode. So if both 1![~::;l!1~~
lights are on, the Keyboard is in the Shift mode.
Control Keys
and
1;'here are 13 Control Keys. Each key outputs asingle control code -
regardless
of what mode the keyboard is in. How the Computer interprets
these control codes depends on the Operating System, but here's a
description
of the typicalfunction of each Control Key:
Escape -Usually used to-exit for asubcommand,
ignoring preceding characters in the current line.
Tab -Advances the cursor to the next tab position. The
software typically sets Tab positionsat 8, 16,24,32, etc.
14

OPERATION
Control Keys (cont.)
Cancels the last character typed and moves the cursor
back
one space.
Interrupts anything in progress in the machine and
returns to the command level.
Pauses execution of the current program. Press
asecond time to continue execution.
Signifies the end
of the current line. The Display Cursor
will
drop to the beginning of the next line. Note that the
two
IMUsil keys are identical. The rightmost
l§lm3;] is for convenient use with the numeric
keypad.
Enters aspace (blank) character and moves the cursor
one space forward.
Cursor Control -Moves cursor back one space without
cancelling previous character.
CursorControl -Moves cursor forward one space with-
out entering ablank-space character.
Cursor Control -In some programs, moves cursor up
one line without erasing previously entered characters.
Cursor Control -In some programs, moves cursor
down one line without erasing previously entered charac-
ters; does not signify end-of-line.
Function Keys -Software Programmable. Outputs a
control codewhich can be used by the Operating System
or Applications Software for special functions.
15

MODEL II OPERATION
Numeric Keypad
Clustered at the right of the Keyboard is aset
of number keys, arrow keys and asecond
key.
The arrow keys and [3IiEil
keys are described above. The number keys
are identical to the
number keys on the top
row
of the main key cluster-except that
these
number keys numeric character
codes only. ,
~ and
keys do not affect the
output from the
numeric key cluster.
These keys are convenient for data entry by
skilled lO-key.operators.
Repeat Key
This special convenience key works in con-
junction with any key combination
in any
mode. Simply hold down
1i;J#l:J::rJiill while
you press the desired key(s). While you hold
down these keys, the keyboard will output a
steady stream
of the desired characters.
Video Display Adjustment
Brightness and Contrast controls are located in the recessed area at the
bottom left of the Display Console. Adjust as necessary for acomfortable
display quality.
B
16

4/ Power-Up Diagnostic Messages
Whenever the Computer is turned on or Reset, it executes abuilt-in
diagnosticprogramto help insure thatthe system
is in goodworkingorder. If
the Computer detects ahardware fault or other problem, it will display an
error message and thenstop. This checkout program reduces thechance that
you will lose time
or data by using adefective system without knowing it.
If one of these error messages is displayed, the first thing you should do is
Reset the Computer, and attempt to duplicate the error. If the message
re-appears, consult the table below.
Note: Thisprogramdoes notcheck for multiplefaults; as soonas asingle fault
is found,
the Computer displays the appropriate message and stops.
DO
Drive not Ready. Improperly inserted diskette
-Re-insert and reset.
Defective diskette -Try another.
Defective Drive.
RS Non Radio Shack diskette. Diskette is not
Radio Shack Model II Operating System for-
mat -Remove, insert proper diskette, and
reset.
(Continued on nextpage)
17

ODEL II OPERATION
ROM (~he(;ksum E~rro]r. Defec:tive ROM.
address range
PI PIO Chip Failure.
OM
MB RAM Fault. Defective RAM in address range
X'OOOO' -X 'OFFF ,
MH RAM Fault (on 64K systems only). Defective
RAM in address range X'8000'-X'FFFF'
81 SIO Chip Failure.
Before you ask for help ...
Try the operation several times. Try using other diskettes. Recheck to see
that all power and interconnections are right.
18

5/Careand Maintenance
Care of Diskettes
In general, handle diskettes carefully, using the same precautions you use
with
tape cassettes and high-fidelity records. Asmall indentation, dust
particle,
or scratch can render all or part of adiskette unreadable-
permanently.
• Keep the diskettein its storage envelopewheneverit is not in one of the
drives.
•
Do not place adiskette in the drive while you are turning the system on
or off.
•
Keep diskettes away from magnetic fields (transformers, AC motors,
magnets, TVs, radios, etc.). Strongmagnetic fields will erasedata stored
on adiskette.
•
Handle diskettes by the jacket only. Do not touch any of the exposed
surfaces. Don't try to wipe or clean the diskette surface; it scratches
easily.
•
Keep diskettes out of direct sunlight and away from heat.
• Avoid contamination
of diskettes with cigarette ashes, dust or other
particles.
•
Do not writedirectly on the diskette jacketwith ahard pointdevice such
as aball point
pen or lead pencil; use afelt tip pen only.
•Storediskettesin avertical file folder
on ashelfwhere they are protected
from pressure to their sides (just
as phono records are stored).
•
In very dusty environments, you may need to provide filtered air to the
Computer room.
Tips on LabelingDiskettes
Each diskette has apermanent label on its jacket. This label is for "vital
statistics" that will never change.
For example, to help keep track of
diskettes, it's agood idea to assign aunique number to each diskette. Write
such a
number on thepermanentlabel. You might also putyour name on the
diskette,
and record the date when the diskette was first put into use.
Remember, use only afelt tip pen for marking.
This
"permanent" label is not agood place to record the contents of the
diskette -since that will change, and you
don't want to be erasing or
scratching out information from this label.
19

MODEL II OPERATION
CustomMfd. inUSAfot.Radio ShackMA Division of Tandy Corporation, Ft. Worth, TX 76102
1"10 Ibaek
n-L_~r.
ModelD:
Microcomputer
Keep such directory information on the storage box or in aseparate
record
book, using the diskette number as akey to all record-keeping.
.. d O\S\{ett
e
NO.
'
baell certd\e
a,ad,e 26.4906
_'--_, cat. No.
lr~~D@(QJ [M]@cQ]@G IOI
certified
Diskette
Figure 7. Labeled diskette.
20

6/ Add-Ons
Inside the Display Console are slots for eight printed circuit boards. Four of
these slots are taken up by the boards required by the basic system -
Processor,
Video Display, Floppy Disk Controller, and Random Access
Memory (RAM).
Adding RAM
If your system has 32K of RAM, you can add another 32K by returning the
unit
to Radio Shack. Another 32K board will be added to the card-cage,
leaving
three slots still open for future enhancement of your system.
Systemsshippedwith64K
of RAM have four slotsopenfor future additions,
since asingle 64K board
is used in place of two 32K boards.
Decimal Address r-~------------.....,
oHexadecimal Address X'OOOO'
32767
32768
65535
32KRAM STOPS HERE X'7FFF'
X'8000'
X'FFFF'
RANDOM ACCESS MEMORYCONFIGURATION AFTER SYSTEM IS INITIALIZED
21

MODEL II OPERATION
Adding DiskDrives
Each drive you add will increase the on-line storage of your system by 509,184
bytes (roughly equivalent to 300 double-spaced typewritten pages).
Connection
of additionalDiskDrives is quite simple. Theconnector is on the
back
of the Display console, and aconnector cable will be supplied with the
Disk Expansion Unit.
Note: When the Disk Expansion Unit is not connected to the Model II, a
special terminatormust be connected to the Disk Expansion connectoron the
back
of the Display Console. This terminator is included with the Computer;
connect it to the
DISK EXPANSION jack.
Further instructionsare provided with theExpansion Unit, and can be added
at the end of this Operation Manual.
Figure 8. Disk Expansion Unit with three additionalDiskDrives.
22