Tandy PC-6 User manual

/~
ITANDY®
•
ervlce
POCKET SCIENTIFIC COMPUTER
PC-6
Catalog Number:26-3672
CUSTOM MANUFACTURED FOR RADIO SHACK, A DIVISION OF TANDY CORPORATION

CONTENTS
PAGE
SPECIFICATIONS
•....••..•..•...........•.........•...•....•..•.•........•.•.. 3
How To Open Upper Case ....................................•............••.. 3
THEORY OF OPERATION
...........•......................•.......••.......... 4
Block Diagram
...•..•••..••••...•.•..........•..•.........•.•.....•.....•••. 4
LSI
•............................. · ......................•.......•......... 5
Ram Map ...••.....•••..........•...........•........•.......•............. 5
Buzzer Control Circu
it •..........................................•........... 6
Interrupt Circuit 6
Keyboard
.•.................................................•.........•... 6
Power Supply
........•..................................................... 7
LSI (Pin Functions)
.....•.....•...•............................................. 8
DISPLAY
•..............•..........................................••......... 9
TROUBLESHOOTING GUIDE
.......•........................................... 10
Test Programs
11
Operation Check ........................................•...•.•.•.....•.... 14
PCB ASSEMBLY VIEWS .......••..........•..•.......•........................ 19
PARTS LIST
...........•..•...........................•...................... 20
Electrical
Parts .........•.................•.........•...................... ,20
Mechanical Parts
..................•........................................ 21
EXPLODED VIEW/DISASSEMBLY INSTRUCTIONS 23
SCHEMATIC
DIAGRAM ...•...•...........•.................................... 24
Main Block
..............••........•..•.....•............................. 24
Keyboard
.•....•.••.............••........••..•.......................... 25
Display
.........•.•..••..••.....•.•.......•..••.......................... 26

Display Method
Display
Calculation
Range
Program System
Program
Language
Number of Variables
RAM Capacity
Program
Areas
Number of Stacks
Subroutine
FOR
'V NEXT
LOOP
Operators
Power Supply
Power Consumption
Battery Life
Memory
protection
battery
Auto Power-off
Ambient Temperature
Dimensions
Weight
SPECI FICATIONS
5 x 7 dot-matrix crystal
24-digit, dot-matrix liquid-crystal display
± 10-
99
'V ±9.999999999 x10
99
Stored System
BASIC
26 fixed variables, exclusive character variable
and array variables
7520 bytes (system
area: 672 bytes)
Maximum
of 10 (PO through P9)
8 levels
4 levels
12 levels
2 lithium batteries (CR-2032) for main frame
1
lithium battery (CR-1220) for memory backup
Maximum 0.07W
1) Continuous program execution: approximately 85 hours
2) Continuous display
of 5555555555 at 68° F(20°C): approximately 200
hours
or 5.5 months when unit is used 1hour per day
NOTE: 1hour includes 10 minutes
of condition 1) and 50 minutes of con-
dition 2)
Approximately 2 years (with main batteries installed)
Approximately 6minutes
32° F
to 104°F (O°C to 40°C)
3/4"H x 5-5/8"W x 2-3/4"D (18 mm x142 mm x 71 mm)
5.8 oz (165 g), including batteries
How To Open Upper Case
Tweezers
1. Insert the tweezers into the back of the upper case.
2. Move tweezers gently in the direction indicated by the
arrow in the figure below.
-3-

THEORY OF OPERATION
Block Diagram
KEYBOARD
a1"Va6, d1"Vd6
b1"Vb6, e1 "Ve6
c1 "Vc6, RD"V R14
Km1"VKm12
DOT-MATRIX DISPLAY
5x7dots, 24 digits
a7"Va12, d7"Vd12
b7"Vb12, e7"Ve12
c7"Vc12, RD"VR14
D1-D8,OP, CE, C1, C2
GATE ARRAY
IC4
MB64H193
RAM IC3
HM6264ALFP
OPTIONS
26-3671
26-3651
CMT 26-3652 26-3652
NOTE: Only one of 2options can be connected at a time.
-4-

LSI
Main CPU
HD61747B20
Sub CPU
HD61747B25
Gate Array
MB64H193
RAM
HM6264ALFP-5Q,
BASIC control, Key signal input/output (lower keyboard), 1st to 6th digits and
13th to 18th digits display control.
Calculation, I/O control, key signal input/output (upper keyboard), 7th to
12th digits and 19th to 24th digits display control.
Interface between CPU and RAM, buzzer control.
Stores data and program. RAM has 8K bytes (64K bits) capacity and contains
aself-control circuit.
Ram Map
LSI ROM
RAM
CPU (Main)
HD61747B20 113024 bits 1896 bits
CPU (Sub)
HD61747B25 113024 bits 1896 bits
RAM
~
HM6264ALFP-50 65536 bits
TOTAL
226056 bits 69328 bits
I nput Buffer
Code Buffer
PH
POT
MFT ST
P5T P4T P3T P2T
P9T P8T P7T P6T
OP
RAM
Variable B
P9B
READ#No.
DATA#P
DATA P
P#X
IN-
KEY
IAddress
P#
GOSUB STACK
DISP Buffer
xD
yD
P#
Varia-
ble No
STEP
P# I~aria-
Address
ble No.
000
080
FOR NEXT
-5-
I P# I~aria-)j
ble No
P# l~aria-..1
ble No.
PASS
IIPRT I
DEFM IMODEI
Address kj i
Users Area
Communication Buffer
Variable check I
$
FF I
100
180

Buzzer Control Circuit
There
are 3ways to operate the buzzer:
Key
input, BEEP 0, and BEEP 1
8
Mode
Frequency
Time
BEEPO
0.9 kHz
110
msec.
BEEP 1
4.55 kHz
110
msec.
Key Input
4.55 kHz
11 msec.
A
82 t----=1..-
..,.,....,
81 ----
M864H193
A ---.fLJLJL
8LSlSlJ
Interrupt Circuit
• Interrupt circuit for the clock pulse when VDD2 drops.
1. When the power is on, VDD2 is "L" level.
2.
PG2 through the ICand 26th pin of the CPU receive PG2.
3. When VDD2 drops, the output of the IC becomes "GND" level and the CPU does not receive
PG2.
PG1
HD61747825
f--- PG2
VDD2
• Interrupt circuit for the voltage of the Gate Array and options when VDD2 and SW drop.
1. When the power is on, VDD2 and SW is "L" level.
2.
VDD2 for Gate Array and VDD4 is also "L" level.
3.
When VDD2 drops, VDD2 for Gate Array and VDD4 becomes "GND" level and stops the op-
ration of the RAM and options.
sw~
VDD2(from IC 4) VDD4
VDD2(from IC 2)
Keyboard
HD61747B25 controls the upper keyboard.
Ks2
Ks3'VKs8 Upper
HD6174782 Ks9, Ks10
~
KeYboard
HD61747B20 controls the lower keyboard.
Km1'VKm4
Km5'VKm10 Lower
HD6174782 Keyboard
Km11, Km12
-6-

Power Supply
VSSl
VRAM
VlrvV5
VDDl
VDD2
Power supply voltage for TC4071 BF.
Memory
used to keep the voltage for the RAM.
LCD drive voltages. Voltage
is generated by connecting the external resistor to VDD2.
Power supply for the CPU, RAM and options.
Stays
VDDl at power-on. Goes to GND at power-off or APO (auto power-off).
-7-

LSI (Pin Functions)
IC1 IHD61747B20
IC2,HD61747B25
Pin No. Signal Name
In/Out Function
1'\,,4
D1,2,4,8
In/Out Data in/out (D1, D2, D3, D4)
5INT
In Interrupt signal from RAM
6'\,,18 KM'\"K1
In/Out
Key signal for keyboard
19
SW
In/Out Switch signal. GND at switch
"OFF" and VDD1 at switch
"ON".
20'\,,24 V5'\"V1
Out Display voltage. Divided vol-
tage from VDD1.
25,26 PG2,PG1 Out, In CPU internal clock
27'\,,72 R15'\"R7
Out Display signal
73 GND In GND
74 CE2
In/Out
Chip designating signal.
Select RAM
or other devices
75 CE1
In/Out Select RAM or other devices
76
VDD1 In Power source
77 VDD2 Out VDD1 output from the LSI.
VDD1
at switch "ON" and
GND switch
"OFF".
78, 79 1/)1,1/)2
In/Out Clock pulse
80
OP
In/Out Operation signal
~ ~:e: 80w ~ ~ b: ~ 0: ~ ii ~ ~ ~
o0 U U<:J a1
> > b1
c1
d1
e1
a2
b2
c2
d2
e2
a3
b3
c3
d3
e3
a4
b4
c4
N ..... LO O ..... NM<::t
~~a:~~ o:o:o:a:a:~~<g:g~~
01
02
04
08
INT
KM
K12
K11
K10
Kg
K8
K7
K6
K5
K4
K3
K2
K1
SW
V5
V4
V3
V2
V1
IC4,MB64H193
37
36
100
02
106
03
ADO
04
107
E
AD1
S1
VSS
VSS
AD2
S2
AD10
B2
AD3
B1
DE
CSO
AD4
CS1
AD11
CS2
LD
coco
N0
(J)
r-- 0
co
en
""
M
12
00
00
0 0 s
(fJ (fJ (fJ (fJ
« « ««
««>a: UUU U 25
13
24
Pin No. Signal Name In/Out
Function
1,2
100,106 In/Out
Data in/out
3
ADO
Out
Address signal
4107
In/Out
Data in/out
5
ADl
Out
Address signal
6V55 In Power source
7,8,9 AD2, 10,3
Out
Address signal
10
OE
Out Output
enable
11'V18 AD4'VAD12
In/Out
Address signal
19
VDD In GND
20
RW
Out Read/write signal
22'V24
CS6'VCS3 Out
Ch ip enable signal
25'V27 C52'VC50 -
NC
28,29
Bl, B2 Out Buzzer signal
30 52 In GND
31 V55 In V55
32
51
In GND
33 E-
NC
34'V37
D4'VDl
In/Out
Data in/out
38
OP
In Operation signal
39,40
C2,Cl
In Clock pulse
41 VDD2 In Power
sou rce
42
CE
In Chip enable
43
VDD
In GND
44'V48 103'V105
In/Out Data in/out
-8-

IC3, HM6264ALFB-50
GND 14
Pin No. Signal Name
In/Out
Function
1 NC
-
NC
2'V10 A12'VAO In Address signal
11'V13 1/01'V1/03
In/Out
Data signal
14 GND In VSS terminal
15'V19
1/04'V1/08
In/Out Data signal
20 CE1 In Chip enable
21
A10
In/Out
Address signal
22 OE Out
Output enable
23'V25 A11,9,8
In/Out
Address signal
26 CE2
In
GND
27
RIW
In Read/write signal
28
VDD In GND
DISPLAY
Numbers and characters are displayed
in 5 x 7 dots.
Following
is an explanation of adot-matrix LCD.
e12 c12 a12 e1 c1 a1
60606 60606
00000 00000
00000 Lower electrode 00000
00000-----------00000
00000 00000
00000 00000
09
090
09
090
d12 b12 d1 b1
R8-o0000 00000
R9--D0000 00000
RIO -00000 Upper electrode 00000
Rl1--Q0000--- ----00000
R12-o0000 00000
R13 -aoooa 00000
1"14 -00000 00000
"----------"Vr---------
Left-half 12 digits
e12 c12 a12 e1 c1 a1
~O~O~ do~o~
00000 00000
00000 Lower electrode 00000
00000--- ----00000
00000 00000
00000 00000
O?O?O 090?0
d12 b12 d1 b1
00000 OOOOo-RO
00000 OOOOD--RI
00000 Upper electrode 0000D-R2
00000--- ---OoOOcr-R3
00000 0000~R4
00000 OOOOo--RS
00000 0000CJ-R6
"-------- __ "V_-------~
Right-half 12 digits
e1 d1 c1 b1 a1
+++-t+-I-+++-++-+ __ -R0
--+++++++++-If+t-I+t--R1
--+++-++++++-1++-+++-R2
--+++-+++t+t-tt++H- R3
--+++-+++-I+t-t+++H-RL.
-+++-+f++f++t+-t++-- RS
-++++H-++-H+t-H+-- R6
On the upper electrode of the LCD, common signals RD'V R6 and R8'V R14
are applied horizontally while
other signals al'Vel to a12'Ve12 are applied
vertically
on the lower electrodes as shown in above figures.
In the left figure, the upper-right corner of the dot is displayed when avol-
tage difference exists between signals
RD and al. The CPU outputs the dis-
play signals
to the LCD display.
CPU HD61747B2D controls the 1st to 6th and 13th to 18th digits of dis-
play, while HD61747B25 controls
the 7th to 12th and 19th to 24th digits.
-9-
-----~-----------------------------------------

TROUBLESHOOTING GUIDE
Symptom Cause Solution
No display at all. Weak batteris Replace the batteries.
Poor battery
contact Clean the battery and contact spring.
Lift the battery spring.
Peeled heat seal Replace the heat seal.
Broken heat seal Replace
the heat seal.
LCD (CA51-TS) Replace the
LCD.
LSI (HD61747B) Replace
the LSI.
Acertain segment(s) Peeled heat seal Replace the heat seal.
cannot be displayed. Broken heat seal Replace
the heat seal.
LCD (CA51-TS) Replace
the LCD.
LSI (HD61747B) Replace
the LSI.
Calculation impossible.
LSI (HD61747B) Replace
the LSI.
Acertain
button does not
Poor key contact
Celan the contact pad on the PCB and the
function. key
contact rubber.
Broken
PC line Connect the
PC line.
Peeled heat seal Replace
the heat seal.
LSI (HD61747B) Replace
the LSI.
-10-
-----------~-- -----------

Test Program
Notes:
1. After typing
in the programs below, save the programs to acassette tape for future use.
2. Memory and printer check programs cannot be executed at the same time because of alimited
memory capacity.
Printer check program
"
MODE 7
PRINT" * *PC-
6CHECK** ";
30 PRINT "ABCDEFGH
IJKLMNOPQRSTUVW
XYZ";
40 PRINT "abcdefgh
ijklmnopqrstuvw
xyz";
50 PRINT "0.123456
789";
60 PRINT "%'@¥[] &+
+-+oo ... x-;-."· ... "I·
o
-l:SiJJYo";
70 PRINT "!#$?\«~
>~t()*/+-Err";
FOR A=l TO 28
PRINT "8";
NEXT A
PRINT "
END-
MODE 8
80
90
100
110
120
Ready PI
LIST
10
20
Ready PI
LIST
5A=0
7A=A+1
10 FOR B=l TO C
20 IF D(B)~B THEN
100
30 NEXT B
40 IF $="ABCDEFGHI
JKLMNOPQRSTUVWX
YZ" THEN 100
50 IF A=5 THEN 110
60 PRINT A;: GOTO
7
100 PRINT "CHECK**N
G**";: BEEP 1:
BEEP 0: GOTO III
101 PRINT "A=";A;
110 PRINT "CHECK**O
K**";: BEEP 1:
BEEP 1
III PRINT "A=";A;:
END
90 GOTO #1
*".
,
Memory check program
Ready p0
LIST
10 CLEAR
20 C=904
25 DEFM C
30 FOR B=l TO C
40 D(B)=B
50 NEXT B
60 $="ABCDEFGHIJKL
MNOPQRSTUVWXYZ"
70 BEEP 1: BEEP 1
80 PRINT "INPUT OK
-11 -

Program SAVE, LOAD and MEMORY
System:
Operation:
IpC61 +
26-3651
or PC-5
cable
(26-3671 )
+ ICMTI
(1) PW SW ON
(2) CMT PLAY MODE
(3) [§J [L~ADI IEXE!
END
(4)
PW SW OFF
(5)
PW SW ON
(6) [II [!]
LOAD
BUZZER RUN DEG
Ready
P0
Take out the 26-3651 +CMT
BUZZER RUN
DEG
Ready P0
BUZZER RUN DEG DEFM
INPUT
OK*
(Buzzer sound)
BUZZER RUN
DEG DEFM
INPUT
OK*l
BUZZER RUN DEG DEFM
INPUT
OK* 1 2
BUZZER RUN
DEG DEFM
INPUT
OK* 1 2 3
BUZZER RUN
DEG DEFM
INPUT
OK* 1 2 3 4
BUZZER RUN DEG DEFM
INPUT
OK* 1 2 3 4CHECK**OK** A=5 (Buzzer sound) OK
(7) IBRKI
BUZZER RUN DEG DEFM
INPUT
OK* CHECK**NG** A=l
-12-
(Buzzer sound) NG

Printer check
System:
I pC-61 +
26-3651
or PC-5
cable
(26-3671 )
+26-3652
PC-4 Printer
(1) PC-6 PW SW ON.
(2) S 2
Print sample:
READY P0
**PC-6 CHECK**
ABCDEFGHIJKLMNOPQRST
UVWXYZabcdefghijklmn
opqrstuvwxyz0.123456
789%'@¥[]&+~+ODAX~ ••
•• ~I·O EQUy6!#$?\«~
>~t()*7+-~TI88888888
8888888888888888888
-END-
-13-

Operation Check
1. When mis-operation occurs, return to the nearest *mark and operate from the *mark.
2. When connecting
the printer and cassette interface, be sure to turn off the power switch.
Operation Read
Out
/RESETl BUZZER RUN DEG
Ready P0
*IMODEI
1BUZZER WRT DEG 7520
P:,¢,-123456789
*IMODEj
~
BUZZER RUN DEG
Ready P0
QWERTYUIOP BUZZER RUN DEG
QWERTYUIOP
'..l..'
, I'
*!BRKj
ASDFGHJKL = ~
BUZZER EXT RUN DEG
ASDFGHJKL =,~,
, I'
*IBRKI
ZXCVBNM; : , IspcI
BUZZER EXT
RUN DEG
lxcvbnm' : '-2..:'
, I I'
BUZZER EXT
RUN DEG
[§J-
- ~<. xcvbnm; : ,
BUZZER EXT
RUN DEG
[§J-
lxcvbnm; : ,
,I,
-
'I'
BUZZER EXT RUN DEG
ICLS I• I /
-
'I'
-14-

Operation
*!BRK!
0.123+456-789*9/3
IEXEI
*IBRKI
IE ( ) t
~ ......
*!BRK]
lM!Jlhypl~ Icoslltanl
~~IEXpl
oM[DEGdJANS!
00 110
xl
*IBRKI
1.2 ISTATI
*IBRKI
[ill~ [TI!EXE I
Read Out
BUZZER EXT
RUN
DEG
-1910.877
BUZZER EXT
RUN
DEG
(Check that the cursor moves.)
E( )t'~
,"
E( )~
'I'
BUZZER EXT
RUN
DEG
UR DEG (-1910.877 t 2 t 310t: ~~
BUZZER EXT
RUN
DEG
STAT1.2,0
BUZZER EXT
RUN
DEG
90
BUZZER EXTRUN
DEG
90 E00
*~IEXTI
A=B*C[llij
-15-
BUZZER
",
'I'
RUN DEG

Operation
Read Out
ICALCI BUZZER RUN DEG
B ?
1231EXEI BUZZER RUN DEG
C?
456!EXE!
BUZZER RUN DEG
STOP
A = 56088
IOUTI BUZZER RUN DEG
STOP
A=B*C
*[MODE!0
BUZZER RUN
DEG
Ready P0
*IMODE! •RUN DEG
Ready P0
*!MODE! •BUZZER RUN DEG TRACEON
IMODEl 2Ready P0
*!MODEI
3BUZZER RUN RAD
!MODEI 5Ready P0
*!MODE! 6BUZZER RUN
GRA
Ready P0
-16 -
._--._------------ ---_.--_.

Operation
Read Out
*!MODE [ 7 BUZZER RUN GRA PRT
ON
Ready P0
!MEMOlm
*]MODE 18
BUZZER GRA 1
, I ,
]MODE 19
-
,,"
QW
!EXEI BUZZER GRA !MEMO
IL1
..
•
EDIT
",
Q-W-
,"
",
-
, I ,
BUZZER GRA
!MEMOIITNl 1
-IEDITI
]INS[
Q, "W
-
,,"
1f0lMQ] llliJ 1
E
[§] IINSI BUZZER GRA
QE" 1/
IEDITI
-
/1 '
IEXE IIMEMOI[&]BUZZER GRA 1
QE
[MfMQ] llliJ
IMEMOj BUZZER GRA 2
", /
-
/ I "
!Asmbl[ BUZZER IASMBLI
Asmbl/Source/ca1
*!BRK!
BUZZER RUN GRA
Ready P0
-17 -
---- -----------

Operation
Read Out
~
9
IMEMOI
..
~~
BUZZER RUN
GRA
!EXE! Ready P0
!MODEI 0
*!MODEI 1
10 BEEP
1BUZZER WRT
GRA
7515
IEXEl 10
BEEP 1
20~D 10 BUZZER WRT GRA 7509
IEXE\ 20 GOTO 10
*!MODEI0
BUZZER RUN GRA
[§J0 (buzzer sound)
!sTopl
BUZZER RUN
GRA
STOP
POWER SW
OFF/ON Repeat 3times. Display must disappear.
Turn the contrast volume. Display should
be "Ready P0."
The display contrast must change.
-18-

PCB ASSEMBLY VI EW
TOP VIEW
TOP VIEW
-19-

PARTS LIST
Electrical Parts
Ref. No. Description
RS Part No. Mfr's Part No.
CAPACITORS
Cl'VC4 Chip, Ceramic, 100pF, 25V, ±5%, CM21CH101J25V ACF-1466 28907311
C5'VC10 Chip, Ceramic, O.lttF, 15V, +100%, CM21YV104P15V ACF-7347 71032167
Cll, C12 Electrolytic, 22ttF, 10V, ±20%, CE04C-1A220MS7 CE·226MCBA 28047223
C13 Electrolytic, 1
OOttF, 1 OV, ±20%, CE04C-l A 101 !\liS CE-107MCBA 28041047
ICs
ICl LSI, CPU, HD61747B20 MX-7273 20018364
IC2
LSI, CPU, HD61747B25 MX-7274 20018801
IC3 LSI, RAM, HM6264ALFP-50 MX-7275 20011149
IC4 LSI, MB64H193 MX-7276 20030453
IC5 IC, TC4071BF MX-4245 21004359
PRINTED CIRCUIT BOARD ASSEMBLIES
PCl Assembly,
PCB-G707-1
82636701
PC2
Assembly, PCB-G707-2 82636702
RESISTORS
Rl'VR9
Chip, Ruthenium, 3.3 Kohm, 1/8W, ±5%, CR32-108-332J-T-TP ND·0230EBN 27930620
Rl0 Chip, Ruthenium, 12 Kohm, 1/8W, ±5%, CR32-108-123J-T-TP ND-0288EBN 27930638
Rll
Chip, Ruthenium, 68 Kohm, 1/8W, ±2%, CR32-108-683G-T-TP ND-0354CBN 27904530
R12
Chip, Ruthenium, 220 ohm, 1/8W, ±10%, CR32-108-221K-T-TP ND-0149FBN 27904734
R13'VR16 Chip, Ruthenium, 3.9 Kohm, 1/8W, ±5%, CR32-108-392J-T-TP ND-0237EBN 27903835
R17'VR21 Chip, Ruthenium, 10 Kohm, 1/8W, ±2%, CR32-108-103G-T-TP ND-0281CBN 27930603
R22
Chip, Ruthenium, 22 Kohm, 1/8W, ±5%, CR32-108-223J-T-TP ND-0311EBN 27903740
R23 Chip, Ruthenium, 2.2 Mohm, 1/8W, ±5%, CR32-108-225J-T-TP ND-0454EBN 27904761
R24 Chip, Ruthenium, 100 ohm, 1/8W, ±10%, CR32-108-101 K-T-TP ND-0132FBN 27904629
MISCELLANEOUS
D1'VD3 Diode, 1S1588, silicon DX-0273 23003031
VRl
Volume, for contrast, 20 Kohm, EVL-AHAAOOB24 AP-7004 27709486
-20-