Block Diagram - Sharp ER-A750 Service Manual

10-1. Block diagram

The block diagram of the weight control function is shown in Figure
10.
DECODER
ADDRESS
WAIT
ENABLE
REGS.
DATA
<00FF8Fh>
In the figure, the decoder, wait enabling register, AND-OR sections
are the same as those in the MPCA5 or 6, but other components are
newly incorporated in the MPCA7.
EXWAITZ and LCDWT are external weight signals which are to be
ORed inside the CPU and output to the WAITZ. The EXWAITZ is a
general-purpose wait request terminal, and LCDWT is the wait re-
quest signal from the LCD controller.
11. CKDC7
The ER-A750 performs the following controls, using CKDC7.
•
Keyboard
•
Customer display
•
Clock
•
Buzzer
•
System reset
11-1 Interface
CKDC7 is connected through the MPCA7.
HTS
TXD2(P87) TXD1
SCK
SCK2(P83) SCL1
STH
RXD2(P84) RXD1
H8/510
IRQ0 IRQ0
RES
MPCA7
STOP
(P57) FT12
RESET
RAS
ROS
IO
X3
ENABLE
1WAIT
WAIT PULSE
GENERATOR
2WAIT
3WAIT
HTS1 HTS
SCK1 SCK
STH1 STH Standard
CKDC7
INT1 KRQ
SHEN
RESET
RESET SRES
STOP
Fig. 11
S
E
L
E
C
T
E
R
ADDRESS
WAIT
CONTROL
REGS.
DATA
<00FF8Dh>
Fig. 10
12. Keyboard
The ER-A750 uses the 13x12 keyboard. The keyboard is controlled
through the CKDC7.
12-1. Interface
CKDC7
/KR0 ~ /KR3
13. RAM expansion bus
As expansion RAM boards, the conventional ER-03MB and 04MB are
used.
SW
13-1. Interface
The ER-03/04 have been originally designed for use in the ER-A850.
Therefore, when using the RAM expansion bus of the same construc-
tion for the ER-A750, the two following points on the interface need
to be considered.
1 Output address change
2 Decode base signal change
Here is the explanation for the above two points:
7 – 30
EXWAITZ
LCDWT
ST0 ~ ST3
/S0~ /S12
LS138
x2
KEX0
KEX1
HC153
x2 x12
/KR0A ~ /KR3A,
/KR0B ~ /KR3B,
/KR0C ~ /KR3C
WAITZ
x13
13 x 12
Keyborad