Radio Shack TRS-80 4P Gate Array Reference manual

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Custom Manufactured in USA By RADIO SHACK. ADivision ol TANDY CORPORATION

Tb Our Customers *.,
Congratulations on purchasing the Model 4P
Disk System. This computer, aportable version
of the Model 4, is botn powerful and efficient.
Using your 4R you can am acomplete line of
application prog rams, including programs for;
•Business
Education
*Personal finance
Programming
Frtlprlflinrnf*nt
This includes all Radio Shack Model ill and
Model 4programs.

How to use this Manual
This manual explains the important things you
need to know about the Model 4P:
*How to set up the Model 4P
*How to use important commands
*How to run application programs
How to Store information
*What to do in case of trouble
After you finish reading this manual, you can
immediately begin running any Radio Shack
Model III or Model 4application programs you
have purchased.
Later, when yuu become comfortable with ine
Model aR you may want to use more est its fea-
tures. You can then read the Disk System Own-
er'sManuei which gives complete details on the
Model 4P commands and BASIC-

Contents
Chapter )How Computers Work I
Chapter 2Getting to Know Your
Model 4P 5
Chapter 3Using TRSDOS to Prepare
Diskettes 15
Chapter 4Runnino. Application Programs 21
Cfjgpfer 5Learning to Proa ram
with BASIC ,27
Chapter 6In Case of Trouble
,
31
Chapter 7And That sJust irie
8eg inning „,..,,. 35
iii

Chapter 1
How Computers Work
Ynur disk system consists ni hwtlwarp. flnrl
software, TTie equipment is the hardware. Tlie
instructions that lei Ithe hardware what to do
aie progiauis or systems, Wtr retei lu these
programs, and systems as software, As you cart
see, hardware and software are dependent on
each other.
Computer Hardware
This picture siiuws Lfm (jails yf Ihe bardwaiy
and how they relate to one another
Keyboard, For "entering" information into the
computer.
Screen and Printer, For receiving information
from the computer
Memory, For storing information and software
inside the computer. The two kinds of memory
•Random access memory (RAM} —for tem-
po rary storage of information and software
that you enter. When you turn off the com-
pi iter, thR mnlents nf HAM disappear
•Read-only memory (ROM) --for permanent
storage of essential, built-in software, such as
the software that telts the computer what to do
when you turn it on. You cannot change the
contents of ROM.
1

Diskette. For permanently storing information
and software outside the computer. Adiskette
has amagnetic coating that stores infonnation
in much the same way an audio tape stores
sound.
Processor Forgathering, manipulating, and
sending information within Ihe computer The
processor ties together all other parts of
the hardware.
Computer Software
This picture shows the kinds of software and
how they itjialtj lu ll ie hardware;
lungutgn
ico lc:1irxi
Rragrimi
Application Programs. To get the computer to
do something practical, such as compile amail-
ing list, you need an application program. Radci
Shack has manv aoolicalion programs (or such
tasks as accounting, educating, and word
processing.
Languages. Aprogramming language, such as
BASIC, is one kind of application program. It
has aset ol codes you can use to write other
application programs, The Model 4Pcomes
with BASIC,
Disk Operating System. An application pro-
gram seldom talks to the hardware directly. It
talks through adisk operating system. The
Model 4P's disk operating system is TRSDOS
Version 6.1.1 (or any later version of TRSDOS
e.1 ). This is called simply TRSDOS'' C"Trias
Doss"3 throughout Ihis manual. TRSDOS is on
the diskette that comes with your Model 4R

To accompisti anything with your system, you
need TRSDOS. Far example, assume you want
the computer to prim afist of your checking
transactions. Ybur application program decides
what to print. It then logvw the operation of the
printer to TRSDOS,
Tfhe rest of this manual shows you how to set up
your Model 4P and how to store information,
using the Model 4R TRSOOS, and an applica-
tion program.

Chapter 2
Getting to Know Your
Model 4P
This chapter tells you rww to set up the Mode1
4R start up your computer, and toad TRSDOS.
It also helps familiarize you with the Mortal 4P
keyboard.
Setting Up the Model 4P
The Model 4P comes with the screen cover on
so you can easily move the computer wherever
you want. To lift the computer, press down on
one end of The handle, then grasp the raised

part of the handle with the other hand as shown
here:
Set the computer where you'll be using it, near
aGrounded, 120 VAC, 3-crong outlet Be sure
the vents on the computer face up. Loosen the
cover from the screen by pushing the latches
back as shown here:
Carefully remote and set aside ihe cover. Then
reach under the main part of the computer and
pul! out the Keyboard, Be careful; the Iseyboard
is perrranenlly connected.
6

Drive 1
urrw Lalches
Drfv* Lights.
Open tha panel on the back of the computer
Connectors for the power cord and additional
equipment are stxjwn below:
Ptiwr
RS232C IOBus Parallel Printer
Connect the power cord to the power connec-
tor, Then plug the other end into the grounded,
120 VAC, 3-prong outlet. Because electrical
mtorfengnccQ and aurgos can dcslroy data, do
not use an outlet that powers other heavy
equipment.
For the best protection against electrical
surges, we suggest you use agrounded power
si rip. agood one to use is Radio Shack's Auto
Control Power Strip and Surge Protector. Cat-
aloa #26-1429.

Installing Other Equipment
If you purchased additional equipment (such as
aprinter), connect it to the appropriate connec-
lur um Lid; bajk uf youi Model 4P Be aura In
refer also to the manual that comes with the
equipment.
ftS-232C Connector Use to connect equ ir>
ment such as amodem or aserial printer.
ParaWp/ Printer Connector—Use to conned
aparallel printer. Connect the cable so it exits
to the bottom of the computer
I!Q Bus Connector —Use to connect one or
more hard disks or other devices. Connect the
cable so it exits to the bottom of the: computer.
Handling Diskettes
Ydu are almost ready to start up your computer,
insert adiskette, and start up TRSDOS. Before
you do. however, take aminute to read about
how to handle diskettes.
Uiskettes are sensitive, lo avoid losing infor-
mation, harxlle them with care.
!T.elO|X:

Dos and Don'ts oi
Diskette Care
Never touch adiskette's exposed shiny
surfaces.
Never turn the computer on or off while adisk-
ette is in adrive. Doing so can destroy data.
Never insert or remove adiskette while the
drive light Is on.
Never leave adiskette inserted in adrive —
either fully or partially— when The computer is
off.
Keep diskettes away from heat, direct sunlight.
dust, cigarette ashes, other particles, and mag-
netic fields Csuch as transformers, AC motors.
magnets. TVs, radios, and the comptJtfir's dis-
play console).
Do not bend diskettes.
Do not write on the diskette label with aball
point pen or lead pencil, Use afelt-tep pen only.
Always put the diskette back in its protective
envelope after use,
Store diskettes in an upright position, never in a
stack. Never place anything on adiskette.
We recommend that you keep your diskettes
either in the manual in which they came or in a
diskette storage box. such as those available
from Radio Shack.
Write Protecting aDiskette
Inside your Disk Sy&tem Owner's Manual is a
diskette labeled "TRSDOS and BASIC Inter-
preter; You 11find atoil, adhesive tab with tne
diskette. Cover the diskette's write-protect

notch" with the foil tab. (Do not pinch the tab
into the notch. 1
When the wiitt)-|jruttHj[ nutuli ia covered, you
cannot change the contents of this "master"
diskette. In the next chapter, well have you
ma« copies of the master diskette.
Starting Up the Model 4P
Turn on any additional equipment first. Then
press the Model 4P's power switch to turn on
the computer. The. switch illuminates 1o indicate
the power is on.
Mote: If you have apower strip, you
can turn all equipment on at Hie same
time by pressing the power switch on
the strip.
Starting Up TRSDOS
In afew seconds, one ofthc messages listed in
Appendix Ais displayed. (Usually, the message
is 'The Floppy Disk Drive is Not Ready"). When
tne drive lights go out, insert the TRSDOS and
BASIC Interpreter diskette (TRSDOS System
HiskflitRt intn Drivs (1 as shnwn below. Be sure
the label laces the screen and the read/wrile
window points into the drive. After fully inserting
the diskette, dose the drive latch.
10

Host* WYiK Window
-> UNI
Wfl1*-P»0tMl *
1H>
To start up TRSDOS, press the RESET switch,
then release it. iNota: Never press (SHIFT) ,
caps),or tfjHU dunnq startup,) The screen dis-
plays the TRSDDS starti ip massage, wtiicti is
simitar to this:
rn-smj* m_c„ ,nphi lag] l«111i>1uu Jbl
.
fl IJ«i ih iBf ptt,mt .ijcm trd i(rltd rCj rMHI Lin
11

Whenever you press RESET the system
returns to Ihis startup message-
Note: If the screen shows a"No sys-
tem' or Not aSYSTEM disk" messanp.
the diskette in Drive does not contain
the operating system. Remove the
diskette and insert asystem diskette,
then press RESET.
At trie bottom 01 tne startup message, TRSDOS
asks:
Dtit iw/dd/yyv
Enter todays date in the format specified. For
example, fur June 14, 19194, type;
D6/14/e4
TRSDOS displays the date in expanded lorm
and Ihen displays the TRSDOS prompt:
TREDQS Ready
Your Model 4P is now under the control of
TRSDOS and is ready for use.
The Model 4P keyboard is much ilke atype-
wri ler keyboard ,except tor atew different keys.
Now's the time to find out vrfiat some of these
keysdo.
At 'TRSDOS Ready,' type anything you ILke.
When you reach the end of the line, press
(SHIFT it) to erase the isne.
12

Continue typing, noting the uses of the tallow-
ing keys;
(X1—Backspaces and erases.
CU —Moves the cursor to the next tab position,
much like atypewriter's CHE key .Tab posi-
tions are at 0. 8. 16. 24, and so on.
(MPS —Lacks the alphabet Keys so you can
enter them in upper-case only for unlocks
Th*n so you can enter them in either upper
or tower-case).
Some keys have afunction only wrier* you are
using an application program, If so, the appli-
cation manual explains how to use the keys.
When finished, press (inter).This moves the
cursor to the beginning of the next line. It also
executes acommand or program, as we'll sftuw
in the fallowing chapters. At this time. Ignore
any messages, suGh as "Program not found."
TflSDOS Ready" shguirj be the last line on
your screen.
Turning Off the Model 4P
Before continuing to the next chapter, please
note the proper way to turn off your Model 4P:
1. To avoid losing any information, make sure
TRSDOS Ready" is the last message
displayed.
2. Carefully remove any diskettes from the
dhves,
3. Then turn off any additional equipment.
4. Now turn off the Model 4P
Note: If you have all ttie equipment
connected to apower strip, then you
can turn it all off at the same time, using
the switch on the power strip.
13

Chapter 3
Using TRSDOS
to Prepare Diskettes
TRSDOSs major role is that of afile cterk. It
organizes each diskette like afilR nahinet and
stores your information in 'disk files; similar to
fife folders.
TRSDOS stores the disk files wherever there i§
space. Files and even parrs of files may be
stored almost anywhere on Hie diskette. The
key to where the files are located is the direc-
tory, which TRSDOS also puts on the diskette.
The DIE and FREE Commands
If you turned off your Mode) 4P at the end of
Chapter 2, turn it on again. Then insert your
master TRSDOS System Diskette as before,
To lei you see what riles are on your diskette,
TRSDOS has adirectory (DIR) command- Start
up TRSDOS and at "TRSDOS Ready.' type:
Dlft SSTEKI
TnSDOG displays the names of all "visible,"
non -system files lhat are stored on your disk-
ette. Now type:
dir (SfU (BQEE
TRSDOS displays the names of qll files on the
diskette, including system files and invisible
files.
Study these files for amoment. In particular,
note the BACKUP and FORMAT fifes. You will
use them later in this chapter.
TRSDOS also has aFREE command, which
shows haw much "froe" (available) space you
have on adiskette.
At' TRSDOS Ready!' lype;
FREE fflEE)
15