Radio Shack System 80 User manual

mAnuAL

This manual is aguide that helps you to get familiar with the System 80 in the
quickest manner. It helps you to set up the system and to operate it efficiently. An overview
of the System 80 is provided so that you will find no difficulty in understanding and
expanding your system. Moreover, higher level computer users will find the technical
information mthe APPENDIX very useful. In case you have any problem or any suggestion
don thesitate to contact your local dealers. Welcome to the exciting world of personal
computing. ^
PREFACE
You are welcome !

yx:.: x:
:::::::... .; :x<• :. •. •:: :x:::.-> ;:::>y :::. .x
CONTENTS Pa* JflBLE QpCOnTEflTT
1. Introduction 3
2. Power On Preparation 5
3. Video Display format 6
4. Keyboard and Cassette 7
5. Program loading g
6. Program Saving . . . ..10
7. Second Cassette Recorder ..,,....,,.,, 11
8. System Reset 12
9. Software ,12
APPENDIX
A. Technical specifications
B. Memory map and I/O map
C. ASCI Itable

The design philosophy of the System 80 Is like that of most other general
purpose computer systems, and has great expansion capability. The main unit (EG3003/4)
contains aCentral Processing Unit, I/O devices and amass storage device. These are the Z80
CPU, akeyboard, avideo interface and aresident cassette recorder. The EG 3003 has
resident 16 Kilobytes of RAM (Random Access Memory) for user's program storage, while
the EG3004 has only 4K. The system has avideo interface and an RF modulator to
display the information on aVDU or aTV,
inTRODUCTIOn
Fig, 1.1

Beside the hardware configuration described, the System 80 has apowerful
resident EXTENDED BASIC Interpreter which is compatible with that of TRS-80 Level II
BASIC.
An optional S-100 bus expansion box is designed to be connected to
main unit. More peripherals can then be linked to the system by plugging their standard
interface cards into the S-100 bus mother-board. S-100 bus is now astandard in the micro
computer industry, especially for computers using 8080 or Z-80 CPUs,
TV OR VDU
TELEPHONE MODEM
EXPANDER
/
r
.. ,/
LiUJj/
ADDITIONAL
RAM
RS-232-C
SERIAL PORT &> ^
This is my family I
4

The System 80 is ready to operate rrriedietely after unpacking from the
carton box. However, the user shouid adhere to the following procedures.
aEnsure that the power switch is in the 'off position.
bCheck whether the AC voltage labelled on the power supply unit is the same as that of
your country.
CConnect the power plug to apower line socket.
dConnect aVoeo Display Unit to the system. The Unit can either be an ordinary TV
set or avideo monitor.
eE-nwe that the 'Video Cut' switch at the back panel sat the out position. The
display format wil be 64 characters/line.
Turn on the power of the display unit *irst, then the System 80.
gAmessage 'READY?' will be displayed on the top left corner of the display.
hI* no '9E- ADY' message is displayed, go to step (a) and check again.
iAfter the READY?' message appears, the user should hit the NEW LINE key, then
another 'READY' message should appear on tie bottom left corr-er of tne display
jNow, the System is at the Active Command level. You can type in commands to get
the computer to work for you. Please refer to the Programming Manual for all the
Active Commands available.
kIf you want to have another display *ormat, please read the next section.
NOTE: If the power switch is turned off for any reason, the user shouid wait at least 15
seconds before turning the power switch on again,
power on
PREPARATIOD
OFF
~~^
TV
or X
N4DISHTQPI
OfSJ
NEW LINE
*«»—*!
r
hi
b

3.1 FORMAT SELECTION
The System 80 allows two kinds of display formats, that Is, (1), 64 characters
per line; (2) 32 characters per line. The purpose of the latter is to permit an enlarged
and clear character display when atelevision set is used,
3.2 64 CHARACTERS/LINE FORMAT
The 64 characters per line format is selected whenever the computer is turned on and
the VIDEO CUT button is off. The user may select 32 characters per line by pressing
the VIDEO CUT button,
3.3 32 CHARACTERS/LINE FORMAT
a) Press the VIDEO CUT button on the back panel.
b) Press the PAGE button on the front panel to read either the left half or the right
half of the text on the display.
3.4 SPACE INSERTION
Aspace can be inserted automatically between characters by typing in
PRINT CHR$(23) This mode will be reset by NEW or CLS command.
VIDEO DI/PLflY
FORfTlfiT
64 characters
per fine
VIDEO CUT
32 characters
per line
i
VIDEO
'That's better !'
ON
rPAGE CUT
i)

The keyboard acts as aman-machine interface, while the cassette is used for mass
storage of programs and data.
4.1 Special Function Keys
PAGE -select page for display (refer to previous section).
Fl —isolate the cassette from the control of the computer during winding and rewind-
ing and allow manual cassette motor control.
BREAK -break arunning program and return to the Active Command Level.
NEWLINE -enter aline of command or data into the computer.
BACKSPACE —cancel the character previously typed.
ESC -the display echoes afsign which is an exponent sign used by the System.
CTL -move the cursor to the beginning of the next line.
SH IFT/CTL/I -tab function; move the cursor 8spaces to the right.
SHIFT/CTL/Y -same as print CHR${23). See section 3.4
SHIFT/BACKSPACE -delete line,
4.2 Cassette Recorder
The cassette recorder is ahigh fidelity audio recorder. It has six piano keys and a
3-digtt counter. The keys function the same as those of anormal recorder. The user should
take the advantage of the counter for fast program locating.
Program loading and saving will be discussed in detail in next section.
KEVBOflRD 6
CPJ/ETTE
PACE Fl CASSETTE RECORDER
POWER
CONTROL
SHIFT
TAPE COUNTER
SPACEBAR BREAK. BACKSPACE NEWLINE SHIFT RECORD REWIND fF PLAY STOP/EJECT PAUSE COVER

Programs are stored on the cassette tapes in the form of magnetic signals. If the user
wants his Computer to do acertain job, he should write the program, save it onto acassette
tape and then reload the program into the system at any time he wants. He may also buy
any TRS80 Level II Basic compatible tapes from the computer market, then load and run
them. The cassette interface is designed to accept awide range of input signal levels,
therefore, no volume adjustment is required.
Now, please follow the procedures below and try to load the demonstration programs
supplied with your System.
5.1 Loading aprogram from the resident cassette (cassette no. 1)
a. Insert acassette into the recorder.
b. CIose thecover of therecorder.
C. Rewind the tape if necessary, (see section 5.2)
d. If you know where is the program located, wind the tape until the counter
indicates the position of the program's beginning.
e. Type in CLOAD# -1 r"N" (where Nrepresents the name of the program) or, type
in CLOAD. The former command tells the computer to search for the suitably
named file, while the second command will only load the first file encountered.
f. Press the PLAY key on the cassette drive.
g. HittheNEWLINEkey.
At this point, the computer starts searching for the program mentioned in the CLOAD
command; once it is found, two asterisks will appear at the top right corner of the display,
the one on the right will be flashing from time to time indicating the program is loading, A
READY message will appear once the loading has been completed.
5.2 Rewinding Procedure
a) Check if the power switch of the computer is turned ON.
b) Press the F1 key (the red light labelled CASSETTE RECORDER should be on also).
c) Press the REWI NDbutton on the cassette drive.
d) Wait till rewinding stops.
e) Press the STOP/EJECT button to stop all operations physically.
f) Reset the cassette counter to OCX).
g) Turn off the F1 button.
PROGRRfTl
LOflDinG
ON REWINDING
REW
SlOP/fJECI
OFF
.:
F1
**
CLflM'JM/'tf
PLAY
m
NEW LINE
8

5.3 Checking aProgram
a) Read the CLOAD command (section 1.5 mthe BASIC Manual.)
b) Rewind the cassette tape to the starting point of the program.
c) Press the PLAY button on the cassette drive,
d) Type mthe command CLOAD? from the keyboard.
e) Hit the NEW LINE key.
Once the computer finds the program, two asterisks will appear on the top right corner
of the display, the one on the right will be flashing if comparison is successful AREADY
message will appear if the comparison has been completed. Otherwise, the word BAD will be
displayed.
i
PLAY
cioao?
**
or
BAD
NEW LINE
5.4 Listing and Executing aProgram
a) Read the LIST and RUN commands (sections 1.9 and 1.11 in the BASIC
Manual).
b) Type in LIST and hit the NEW LINE key (The entire program will be listed on the
display).
c) Type in RUN and hit the NEW LINE key (The computer starts executing the
program).
[new lineJ
NEW LINE
WARNING :CASSETTE LOADING
Although the cassette interface circuit can tolerate wide range of input signal level,
sometimes, loading error may occur. The reason is that so many software houses produce
TRS-80 compatible tapes and their quality may differ a lot The only solution is to do a
backup for yourself and use the backup copy for future loading.
The backup procedure should be: —
0) Put the TRS-80 compatible tape into second cassette.
(2) Connect the second cassette to the computer.
(3) Use CLOAD #—2, 'f command to load the program into memory.
(4) Try to adjust the second cassette volume if loading fails,
(5) If the program is successfully loaded, save it onto ablank tape with cassette #1
.

0.1 Winding the Tape to the Proper Location
a) Press the F1 key {the red light labelled CASSETTE RECORDER should be on as
well).
bl
c)
d)
Press the REWIND or FAST FORWARD key and set the tape to the location
where program saving starts.
Press the STOP/EJECT key to physically stop tape winding operations.
Press the RECORD and PLAY keys simultaneously, to clear apart of the tape
before actual saving.
e) Rewind the tape alittle to ensure the entry point for program saving is clear;
f) Release the F1 key (the red light labelled CASSETTE RECORDER should be off).
6.2 Program Saving
a) Type in CSAVE #-1, "N" {where Nrepresents afile name).
b) Press the RECORD and PLAY key simultaneously.
c) Hit the NEW LINE key.
The red light labelled CASSETTE RECORDER should be turned on automatically, and
the cassette should be recording the signal from the computer. However, no asterisk will
appear on the display. Aready message will be displayed after the saving has completed.
6.3 Program Checking
After the program has been saved on tape, it is necessary to check whether the program
on tape is atrue copy of the one in the computer. Program checking is provided in the
System 80, Please read section 5,3, "CHECKING A PROGRAM".
PROGRRfTl
/RVIRG
ON
F1
REW
REC PLAY
c$AYE#a**ir
REC PLAY
IT
NEW LINE
10

Two cassette recorders are required in some applications such as payroll and account-
ing. In these applications, old data have to be read into the computer sequentially from one
file and output to another file after processing or updating. The main unit already has the
interface for one more cassette recorder. Signal input/output is through the DIN jack at the
back panel, Acassette recorder cable is packed with the System.
Active Commands and instructions are provided to handle this extra cassette, These
are ;—
(i) CLOAD #-2, "M" -load aprogram called Mfrom cassette *2'.
(ii) CSAVE #-2, "M" -save aprogram onto cassette '2'.
(iii)PRINT#-2,A,B,C$ -store the variables ArBand character string C$ onto cassette '2\
(iv) INPUT#-2rA,B,C$ -input the variables A. Band character string C$ from cassette '2'.
For further programming details, ptease refer to the BASIC Manual, The operating
procedure of the cassette '2' for playing (reading in data) or recording (outputting data onto
the tape) is same as that described in 4.1
/econo
CflXTETTE
RECORDER
Note; —The user may have to adjust output volume of his cassette untif no error occurs
during cassette loading. The System 80 may have to be reset if invalid
data is read and causes adead loop.
WHITE TO MtC
BLUE TO REMOTE
BLACK TO EAR
mm VOLUME ma*
That's my heart-beat!!
11

The system must, in some cases be reset. When, for example, the machine is running in
adead loop. The Reset Switch is located at the right side of the back panel. Pressing the
reset switch causes the computer to return to the 'READY' mode without changing the
memory contents.
The system runs in adead loop in the following cases;
(1) loading aprogram from the cassette which contains an invalid file, or when the
volume of the recorder is poorly adjusted,
(2) executing LPRINT or LLIST instructions without hooking up aprinter to the
system or having not turned on the printer.
(3) executing an inappropriate POKE instruction.
The CPU is reset everytime when the power is on. Turning the system off and on
immediately is not agood practice; because it may cause improper initialization of the CPU.
Therefore, the user should wait for about 15 seconds before turning on the system again.
/V/TEm RE/ET
Help!
The System 80 operates on ahigh level language called BASIC. The system's
Extended BASIC is compatible with that of TRS80 Level fl BASIC, Therefore, TRS-80's
tapes can be loaded into the system and run. Further details of the BASIC language are
explained in the BASIC Manual.
The System can also load binary tapes that contain Z80 machine codes. For loading
such tapes, please refer to the SYSTEM command discussed in the BASIC MANUAL.
/OFTWflRE
12

m
POWER CONSUMPTION
CASSETTE INPUT LEVEL
COMPUTER OUTPUT RECORDING LEVEL
19REMOTE SWITCHING CAPACITY
VIDEO OUTPUT
C2J CONNECTORS PIN ASSIGNMENTS
RPPEflDIH fl
25W (MAX.J TECHfllCflL
1Vpeak to peak /PECIFICATIOflf
0,3 Vpeak to peak
0.5 Amax at 6VDC
—2Vpeak to peak
(Negative sync pulse)
DIN JACK PIN CONNECTIONS FOR ADDITIONAL CASSETTE
1-REMOTE
2-SIGNAL GROUND
3-REMOTE
4-INPUT
5-OUTPUT
DIN JACK PIN CONNECTIONS FOR VIDEO INTERFACE
1~+5V
4-VIDEO OUTPUT
5-GROUND
DIN JACK VIEWED FROM REAR SIDE OF THE SYSTEM.
EXPANSION PIN EOGE VIEWED FROM REAR SIDE 50
=3
49
13

PIN CONNECTIONS FOR EXPANSION INTERFACE
PIN SIGNAL
1GND
2GND
3A7
4A6
5A5
6A4
7A1
8A3
9A2
10 A0
11 D5
12 D2
13 NC
14 D1
15 DO
16 D3
17 D7
18 D6
19 VCC
20 D4
21 A15
22 A8
23 A14
24 A9
25 NC
DESCRIPTION
GROUND
GROUND
+5V SUPPLY
NO CONNECTION
PIN SIGNAL DESCRIPTION
26 A10
27 A13
28 A11
29 A12
30 PHI 1.79 MHz dock
31 PINT INTERRUPT
32 NC NO CONNECTION
33 NC NO CONNECTION
34 PHLDA PROCESSOR HOLD ACKNOWLEDGE
35 PHANTOM PHANTOM
36 HALT HALT ACKNOWLEDGE
37 PWAIT PROCESSOR WAIT
38 10RQ INPUT/OUTPUT REQUEST
39 PHOLD PROCESSOR HOLD
40 WR PROCESSOR WRITE
41 RD PROCESSOR READ
42 CCDBS/STADBS CONTROL AND STATUS BUS DISABLE
43 MREQ MEMORY REQUEST
44 DODBS/ADDBS DATA AND ADDRESS BUS DISABLE
45 Ml FIRST STATE OF INSTRUCTION CYCLE
46 RESET CPU RESET
47 RFSH DYNAMIC MEMORY REFRESH
48 NMI NON-MASKABLE INTERRUPT
49 GND
50 GND
14

MEMORY MAP
FFFF
'7FFF
3CO0-3FFF
3800-37 FF
2FFF
0000
FOR EXPANSION
16K RAM
RPPEDDIH B
mEmoftv mfip 6
i/o mflp
VIDEO DISPLAY MEMORY
RESERVED FOR KEYBOARD
ROM
I/O PORT ASSIGNMENT
CASSETTE INTERFACE -FF, FE
PRINTER INTERFACE -FD
15

HEX DECIMAL CHARACTER HEX DECIMAL CHARACTER
OD
20
21
22
23
24
25
26
27
28
29
2A
2B
2C
2D
2E
2F
30
31
32
33
34
35
36
37
38
39
3A
3B
3C
3D
3E
3F
13 CR (AUTO LF)
SPACE
#J
36
37 %
43
44
1
2
3
7
8
60
63 >
?
40 64
41 64
42 66
43 67
44 68
45 69
46 70
47 71
48 72
49 73
4A 74
48 75
4C 76
4D 77
4E 78
4F 79
50 80
51 81
52 82
53 83
54 84
55 85
56 86
57 87
58 88
59 89
5A 90
5B 91
5C 92
5D 93
5E 94
5F 95
@
A
B
C
D
E
F
G
H
I
J
K
L
M
N
P
Q
R
S
T
U
V
w
X
Y
z
[
\
J
A
flPPEHDIH C
fl/CII TRBLE
16