Radio Shack TRS-80 PC-4 User manual

LIMITED WARRANTY
r
I.
II.
III.
TERMS AND CONDITIONS OF SALE AND LICENSE OF RADIO SHACK COMPUTER EQUIPMENT AND SOFTWARE
PURCHASED FROM A RADIO SHACK COMPANY-OWNED COMPUTER CENTER, RETAIL STORE OR FROM A
RADIO SHACK FRANCHISEE OR DEALER AT ITS AUTHORIZED LOCATION
CUSTOMER OBLIGATIONS
A. CUSTOMER assumes full responsibility that this Radio Shack computer hardware purchased (the "Equipment"), and any copies of Radio
Shack software included with the Equipment or licensed separately (the "Sottware") meets the specifications, capacity, capabilities,
versatility, and other requirements of CUSTOMER. .
B. CUSTOMER assumes full responsibility for the condition and effectiveness of the operating environment in which the Equipment and Software
are to function, and for its installation
RADIO SHACK LIMITED WARRANTIES AND CONDITIONS OF SALE
A. For a period of ninety (90) calendar days from the date of the Radio Shack sales document received upon purchase of the Equipment, RADIO
SHACK warrants to the original CUSTOMER that the Equipment and the medium upon Which the Software is stored is free from manufacturing
defects THIS WARRANTY IS ONLY APPLICABLE TO PURCHASES OF RADIO SHACK EQUIPMENT BY THE ORIGINAL CUSTOMER FROM
RADIO SHACK COMPANY-OWNED COMPUTER CENTERS, RETAIL STORES AND FROM RADIO SHACK FRANCHISEES AND DEALERS AT ITS
AUTHORiZED LOCATION. The warranty is void if the Equipment's case or cabinet has been opened, or if the Equipment or Sottware has been
sUbjected to improper or abnormal use. If a manufacturing defect is discovered during the stated warranty period, the defective Equipment
must be returned to a Radio Shack Computer Center, a Radio Shack retail store, partiCipating Radio Shack franchisee or Radio Shack dealer
for repair, along with a copy of the sa~es document or lease agreement. The original CUSTOMER'S sale and exclusive remedy in the event of
a defect is limited to the correction of the defect by repair. replacement, or refund of the purchase price, at RADIO SHACK'S election and sole
expense. RADIO SHACK has no obligation to replace or repair expendable Items
B. RADIO SHACK makes no warranty as to the design, capability, capacity, or suitability for use of the Software, except as provided in this
paragraph. Software is licensed on an "AS IS" basis, without warranty. The original CUSTOMER'S exclusive remedy, in the event of a
Software manufacturing defect, is its repair or replacement within thirty (30) calendar days of the date of the Radio Shack sales document
received upon license of the Software. The defective Software shall be returned to a RadiO Shack Computer Center, a Radio Shack retail store,
participating Radio Shack franchisee or Radio Shack dealer along with the sales document
C Except as provided herein no employee, agent, franchisee. dealer or other person is authorized to give any warranties of any nature on behalf
of RADIO SHACK.
D. Except as provided herein, RADIO SHACK MAKES NO WARRANTIES, INCLUDING WARRANTIES OF MERCHANTABILITY DR FITNESS FOR A
PARTICULAR PURPOSE.
E. Some states do not allow limitations on how long an implied warranty lasts, so the above limitation(s) may not apply to CUSTOMER.
LIMITATION OF LIABILITY
A. EXCEPT AS PROVIDED HEREIN, RADIO SHACK SHALL HAVE NO LIABILITY OR RESPONSIBILITY TO CUSTOMER OR ANY OTHER PERSON
OR ENTITY WITH RESPECT TO ANY LIABILITY, LOSS OR DAMAGE CAUSED OR ALLEGED TO BE CAUSED DIRECTLY OR INDIRECTLY BY
"EQUIPMENT" OR "SOFTWARE" SOLD, LEASED. LICENSED OR FURNISHED BY RADIO SHACK. INCLUDING, BUT NOT LIMITED TO. ANY
INTERRUPTION OF SERVICE, LOSS OF BUSINESS OR ANTICIPATORY PROFITS OR CONSEQUENTIAL DAMAGES RESULTING FROM THE
USE OR OPERATION OF THE "EQUIPMENT" OR "SOFTWARE" IN NO EVENT SHALL RADJO SHACK BE LIABLE FOR LOSS OF PROFITS, OR
ANY INDIRECT, SPECIAL, OR CONSEQUENTIAL DAMAGES ARISING OUT OF ANY BREACH OF THIS WARRANTY OR IN ANY MANNER
II ole IW':! nliT n~ no ('n~I~I~(,T~n Ill/ITI.I TI.I~ CIII ~ I ~IIC:J: I Ir~NC:~ IIC:~ ()Q Ap.ITlrIPAn:n IIC.~ ()~ TI.I~ "~()IIIPM~NT" nQ "c.nJ=TWMl:I="

NOTWITHSTANDING THE ABOVE LIMITATIONS AND WARRANTIES. RADlO SHACK'S LIABILITY HEREUNDER FOR DAMAGES INCURRED BY
CUSTOMER OR OTHERS SHALL NOT EXCEED THE AMOUNT PAID BY CUSTOMER FOR THE PARTICULAR "EQUIPMENT" OR "SOFTWARE"
INVOLVED.
B. RADIO SHACK shall not be liable for any damages caused by delay in delivering or furnishing Equipment and/or Software.
C. No action ansing out of any claimed breach of this Warranty or transactions under this Warranty may be brought more than two (2) years
after the cause of action has accrued or more than tour (4) years after the date of the Radio Shack sales document for the Equipment or
Software, whichever first occurs.
D. Some states do not allow the limitation or exclusion of incidental or consequential damages, so the above limitation(s) or exclusion(s) may
not apply to CUSTOMER.
IV. RADIO SHACK SOFTWARE LICENSE
RADIO SHACK grants to CUSTOMER a non-exclusive, paid-up license to use the RADIO SHACK Software on one computer, subject to the following
provisions:
A. Except as otherwise provided in this Software License. applicable copyright laws shall apply to the Software.
B. Title to the medium on which the Software is recorded (cassette and/or diskette) or stored (ROM) is transferred to CUSTOMER, but not title to
the Software.
C. CUSTOMER may use Software on one host compute I and access that Software through one or more terminals if the Software permits this
function.
D. CUSTOMER shall not use, make, manufacture. or reproduce copies of Software except for use on one computer and as is specifically
provided in this Software License. Customer is expressly prohibited from disassembling the Software.
E CUSTOMER is permitted to make additional copies of the Software onlv for backup or archival purposes or if additional copies are required in
the operation of one computer with the Software, but only to the extent the Software allows a backup copy to be made. However, for
TRSDOS Software, CUSTOMER is permitted to make a limited number of additional copies for CUSTOMER'S own use
F. CUSTOMER may resell or distribute unmodified copies of the Software provided CUSTOMER has purchased one copy of the Software for each
one sold or distributed. The provisions of this Software License shall also be applicable to third parties receiving copies of the Software from
CUSTOMER.
G. All copyright notices shall be retained on all copies of the Software.
V. APPLICABILITY OF WARRANTY
A. The terms and conditions 01 this Warranty are applicable as between RADIO SHACK and CUSTOMER to either a sale of the Equipment andior
Software License to CUSTOMER or to a transaction whereby RADIO SHACK sells or conveys such Equipment to a third party for lease to
CUSTOMER.
B. The limitations of liability and Warranty provisions herem shall inure to the benefit of RADIO SHACK, the author. owner and/or licensor of the
Software and any manulacturer 01 the Equipment sold by RADIO SHACK.
VI. STAn LAW RIGHTS
The warranties granted herein give the original CUSTOMER specific legal.rights. and the original CUSTOMER may have other rights which vary
from state to state.

Thank you very much for purchasing the PC-4. This handy, personal computer is
excellent for those who are beginning to learn about computers.
With
the PC-4, you can enter the world of computers and start programming using
BASIC language.
CONTENTS
Prior to Operation ..........................................·3
Use Precautions .........................................•. 3
Power
Supply and Battery Replacement ••.••..•..................... 4
Chapter 1Name and Operation of Each Section 5
1·1 Name of Each Section 5
1-2 How
to Read the Display .•................................. 10
Chapter 2Prior to Ca Icu lati ng 11
2-1 Contrast Adjustment .........................•............ 11
2-2
RAM Expansion Pack . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 11
2-3 Memory Expansion •.•.....•.• " .•.•.••..................... 12
2-4 Auto Power Off '" '" " II • "II II II III '" 13
Chapter 3 How to Ca Icu late 14
3-1 Calculation Priority Sequence 14
3-2 I nput/Output and Operation Number of Positions 14
3-3 How to Perform Fundamental Calculations 15
3-4 Callout of Previous Calculation Result 16
3-5 Error Messages
17
3-6 Key Operation 17
Chapter 4Manual Calculation 20
4-1 What Is Manual Calculation? 20
4-2 Operation Method for Manual Calculation 20
4-3 Manual Calculation Examples
21
4-3-1 How to Perform Fundamental Calculation ................•.•.•... 21
4-3-2 How to Perform Function Calculation 23
4-4 Arrays III II Ii II '" .. '" I- Ii 26

Chapter 5Program Ca I cu lation ...............................27
5-1 Program Outline ............••................. ......•... 27
5-2 Program Fundamentals
...............................•.•... 28
5-2-1 Constants and Variables ...•••....•.•.••.......•..........••••. 28
5-2-2
Substitution Statements •.•..•..........•...................... 29
5·3 Program Writing and Execution ...........................••.. 30
5-3-1 Program Writing ...•.••...••.••••.•...............•...• 30
5-3-2 Program
Execution •...•••...••••....................... 32
5·4 Program Editing .................•.....•.•..••.....•..... 34
5-5
Program Debug "" .. .. .. 40
5-6 Program Commands
.............•••.••..•..•.............. 44
5-6-1
5-6-2
5-6-3
5-6-4
&-6-5
5-6-6
5-6-7
5-6-8
5-6-9
5-6-10
5-6-11
5-6-12
5-6-13
5-6-14
5-6-15
5-6·16
5-6-17
Input Command (INPUT, KEY) 44
Output Command (PRINT, CSR) 45
Jump Command (GOTO) .•.•...•••...•.................• 47
Judgement Command
(IF - THEN) ..•....•...•...•••.•.•.... 48
Loop Command (FOR·NEXT) ....•••.•..•..•.............. 49
SUbroutine Command (GOSUB,
RETURN) ................•....• 51
Multistatement .....•.•.•.•.•••..••...•.•.•.....•••.• 54
Stop Command (STOP) •.•••••...•.•.•.............•.... 54
End Command (END) ...•...•.•...............•.•.•••.. 54
Execute Command (R UN) .•...•.............•.•.•....•.•• 54
List Command (LIST) .........................••••.•... 55
Mode Designation (MODE)
•••.•.................••.•••.•. 55
Output Format (SET) .......•...............•••.•...... 56
Character Functions (LEN, MID, VAL) ...............••••..... 56
Memory Clear (V AC) ..................•.....•....•...•. 57
Program Clear
(CLEAR, CLEAR A) .............•.••.•...•.•. 57
Option Specifications .................................•• 58
Cassette Magnetic Tape
(SAVE, LOAD, SAVE A, LOAD A, PUT, GET, VER). 58
Printer ...................................•••.•• 60
Error Message List It 61
Program Command List I ................................................... •'62
Function Digit Capacity 64
Specifications 65
-2-

This computer is delivered to you through our strict testing process, high-level
electronics technology and rigid
quality control.
In order to ensure the longevity of the computer, please be sure to note the following
precautions.
•Use Precautions
•Since the computer is constructed using precision electronics parts, never attempt to
take it apart. Also, do not subject the computer to shock such as throwing or drop-
ping
it and avoid extreme temperature variations. Be especially careful to avoid high
temperature locations where there
is also high humidity or a lot of dust. However,
if the ambient temperature is too low, the display response speed may be slow or
there may be no display. When normal temperature conditions are resumed, the
computer
will operate normally_
•Do
not attempt to connect any equipment to the adapter socket other than our
exel usive optional equipment.
•While the
computer is operating, a "_" (dash) will be displayed. At this time, key
operation
will be ineffective except for one section. Therefore, always be sure to
press the keys while confirming the display.
•
Be sure to replace the batteries every 2years regardless of the amount of use.
Worn out batteries may leak and cause a malfunction. Therefore, never leave old
batteries inside the computer.
•
To keep the computer clean, wipe off surface with a soft, dry cloth or one which
has been dampened with aneutral detergent.
•In
case of malfunction, contact the Radio Shack store where it was purchased.
•Prior
to seeking service, please read this manual agaip and check the power supply
as well as the program. Also, an operational error may be the cause of an apparent
malfunction.
-3-

•Power Supply and Battery Replacement
This instrument uses two lithium batteries (CR2032 Cat. No.23-162) for a power supply.
If the display contrast is weak even when the contrast control is adjusted for maximum,
(refer to page 11)Ithe batteries should be replaced at the earliest opportunity.
Be sure to replace the batteries every 2years.
SCrews
I
• How to Replace the Batteries
(1) After turning the power sWitch off, loosen the two
screws on the back and then remove the rear panel.
I
.. -:t.
I
°1
[Q]]
I
ALL RESET button
(2) While pressing on ® ' slide the battery compart-
ment lid in the direction of the arrow and remove it.
(3) Remove the old batteries.
(This
will be easier if you tap the unit lightly
with the battery compartment facing down.)
~Oi
o0
®
(4) Using a dry cloth, wipe off the new batteries and
insert
them with the EEl (positive) side facing up.
(5) Slide
the battery compartment lid closed while
pressing down on the batteries.
(6) Replace the rear panel and tighten the screws.
After turning the power switch on, press the ALL
RESET button with a pointed object.
-4-

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®
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PAT OM
PAT OFF
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GOTO
PC-4
WRT TRACE ON IJlTAACEOFF
ON
'NS
~<-
-EXT -MODE
!i
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®
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>
POWER 1I
ummo
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1[[1] -ON (g) I ¢= I 19> ]m SHFT - P4 PS P6 ,. '-
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-.1 "-.-$-l-I-?-:-;-~ II g II a
[~) ~ ep (~I cp cp up CD (Q] I ~ I P1 P2 .3 '"
CPCPcjJCPciJ@cpcpcp~~~1J1l
r~j qJ (E~] (7!,l~' I~T) [~) (SPCI (;) I ciJ ma Em
1T
CD Adapter connector
®Display window
® Shift key
@Power switch
@Mode key
®Display contrast control
(j)Calculation instruction keys
@Execute key
®Numerical keys and decimal point key
@Alphabet keys
Each key has 1or 2operations. The operations can be divided by using the Shift Out
mode, whereby the keys are pressed directly, and the Shift In mode, whereby keys are
pressed after pressing the ~ (SH IFT) Key.
Example:
GOSUB .~~ Sh ift In mode
OD~-Shift Out mode
-5-

Key operation in the Shift Out mode
IM@@]~[]]
C2JlRJ[[)OO[!J[Y][illO]@][E]
0[[]~[[]@](]JQ][[]w~
000[]JCYJ[[)ffi](MJ~§]OO
Key operation in the Shift In mode
.I .. 1* $ ( ) ? : ; •
C=:lc:::::Jc:::::J~~c:Jc:Jc:lc:lc::::J
GOSUB FOR TO STEP NEXT GOTO IF THEN PRINT (ANsi
c:Jc:lc:Jc:::Jc:::Jc:::Jc:J~c:J
RETURN STOP END DEFM RUN LIST INPUT (SPC) 4: 7r
~c:JC::>c:Jc:Jc::Jc:J c:=lc:J
ma JOEll [STOP] a
[2][aJ~D
~@(§Ja
C1J~@)D
~8[ EXE I
P7 P8 P9 >
c::::J c:=l c:J c:::>
P4 P5 P6 .::S
c:::::J c:Jc:J c:::::J
P1 P2 P3 ::::-
c:::::J c:J c:J c:J
8cSl EXE )
*. In the Shift In mode, the alphabet keys become one-key commands and the
numerical keys become program
area designation keys.
•In addition, using the Extension Mode
(press ~c:::J and "EXT" shows on display),
while in the
Shift In mode results in special symbols displayed for each alphabet
key
that is pressed. Lower case letters will be displayed, however, if the Extension
mode
is used while in the Shift Out mode.
Shift In mode using the extension mode
c=Jc=Jc:=Jc::Jc:::Jc:::Jc=Jc:::Jc:::JD
oD ~ x+ • • • •
c:::Jc:::Jc:::Jc=Jc:::Jc:::Jc:::JDDD
• • 0 - ~ n ft
Shift Out mode using the extension mode
[I]800[!]lIJ0OJ~~
00(]JITJ[]][E]OJ[I)OJD
0000~~8DDD
-6-

WSHIFT Shift Key (Symbolized by ~ hereafter)
If this key is pressed, the Shift In mode is selected (" W" is displayed) and the Shift In
functions on the keyboard can be used. Do not confuse m(red key) with the regular
(]J (letter "S").
1111I1 Mode Key
This is pressed in conjunction with GJ and (el through ~ Keys to designate the
computer's
condition or angular unit in advance.
~8 "EXT" is displayed. The Extension mode is designated and lower case
letters or special symbols can be used, depending on whether the Shift In
or Shift Out modes have been previously selected. To release the Exten-
sion mode
press ~8 again.
I!!!lIDl "R UN" is displayed. Manual calculation and program execution can be
performed.
~lIJ "WRT" is displayed. Program write-in and checking/editing can be per-
formed.
~~ ....... "TR" is displayed. Execution trace can be performed. (See page 43 for
details.)
~~ "TR" disappears from display. This mode disables the execution trace
function( ~~ ).
~~ "DEG" is displayed. The angular unit will be designated as "degree".
1!!!lU2] "RAD" is displayed. The angular unit will be designated as "radian".
~~ "GRA" is displayed. The angular unit will be designated as "gradient".
~l2J "PRT" is displayed. If a printer is connected, printout can be performed.
~(S) -... "PRT" disappears from display. This mode disables the printout function
(~l21 ).
[¢::'Hc:;>! Cursor Keys
Press to move the cursor left or right. If pressed once, cursor moves one character
space. If kept pressed the cursor continues to move automatically.
ON
• All Clear/ON Key
• Press to clear the entire display.
•
If pressed during program execution, program execution will stop.
•When
an error message is displayed, press to clear the error message display.
•When auto power
off is in operation (automatic energy saving function, refer to page
13). and the display is off, press to turn power back on.
INS
IOELI Delete/Insert Key
•Deletes one character at the position of the bl inking cursor.
•In the
Shift In mode, press to open up one character space for character insertion.
-7-