Memory Circuits; Fig. 2.9 Memory Connexion - ELCOM Euro-500 Handy Series Service Manual

Euro-500TX Handy
Pin #. Signature
80 P-LOW
81 PS1
82 PS2
83 HS
84 DRAWER
85 BUZZER
86 GND
87 RDKEYB
88 RW1
89 CS2
90 CS1
91 CS0x
92 GND
93 PR-SEL
94 PR-SET
95 A
96 B
97 SAVEPWR
98 EN
99 CS4
100 NC
Tab. 2.1 Description of the E-500TXN microcontroller signals (cntd.)

2.2.2 Memory circuits

The memory used by the microcontroller is divided into the two parts:
• programme memory
• data memory
The EPROM memory with the capacity of 256 kB serves as the programme memory. The data memory is
built on the static RAM memory (68C1000, 66C1024) and is expandable to 512 kB. The programme memory
(EPROM) is activated using the CS0 signal and the data memory (SRAM) is activated using the CS1 signal.
The ECR Euro-500TX handy uses
the ultra low power input memory
circuits that allow the lower power
supply demands and significantly
prolongs the backup of memory data
using the backup accumulator. The
exchange of said memory circuits
for other types with same capacity
can result in worse performance of
memory operations, increase of the
bus interference, and the memory
back-up time is shorter. It is recom-
mended to use only manufacturer
approved memory circuits.
In order to preserve the data in RAM
memory while the ECR is off, the
RAM memory is backed up from the
reserve accumulator.
Note: The chapter 4.7 describes how
to expand ECR memory to 512 kB.
Service manual
Type Signal description
I scanning voltage value of internal connecting accumulator
I scanning paper ribbon presence
I scanning paper ribbon presence
I scanning printer head position
O control signal for drawer opening
O buzzer control
I 0 V power supply
O signal for reading keyboard and JP4 - JP6 jumper condition
I scanning keyboard
O current time circuit activation
O RAM memory activation
O program memory activation
I 0 V power supply
activation of circuit for production of STB1 – STB4, W-MOT and PLATCH
O
signals
O control output for number of check bits written in one cycle to fast print circuit
O 1. phase of printer stepping motor
O 2. phase of printer stepping motor
O signal of switching between normal and saving mode
O activation signal of stepping motor drivers
signal of data recording to circuit for production of STB1 – STB4, WMOT and
O
PLATCH signals
NC
U2
A0
12
A0
A1
11
A1
A2
10
A2
A3
9
A3
A4
8
A4
A5
7
A5
A6
6
A6
A7
5
A7
A8
27
A8
A9
26
A9
A10
23
A10
A11
25
A11
A12
4
A12
A13
28
A13
A14
3
A14
A15
31
A15
A16
2
A16
S17
30
A17
A18
1
A18
KM681000A
R25
A17
0R(opt. 4000)
R26
VRAM
10k

Fig. 2.9 Memory connexion

D0 A0
13
D0
D1 A1
14
D1
D2 A2
15
D2
D3 A3
17
D3
D4 A4
18
D4
D5 A5
19
D5
D6 A6
20
D6
D7 A7
21
D7
A8
A9
A10
A11
A12
A13
CS1 A14
22
CS1
A15
RD A16
24
OE
A17
HWR
29
WE
R27
S17 VRAM CS1
10k
© Elcom, s. r. o.
U3
D0
12 13
A0 DQ0
D1
11 14
A1 DQ1
D2
10 15
A2 DQ2
D3
9 17
A3 DQ3
D4
8 18
A4 DQ4
D5
7 19
A5 DQ5
D6
6 20
A6 DQ6
D7
5 21
A7 DQ7
27
A8
26
A9
23
A10
VCC
25 1
A11 VPP
4
A12
28 31
A13 PGM
29
A14
CS0
3 22
A15 CE
2
A16
RD
30 24
A17 OE
27C2001+Socket
15