System Bus - Tandy 102 Service Manual

System Bus
In order to expand the use of external devices, a 40-pin system bus connector is mounted on the
back panel of the Tandy 102.
As shown in the Table 4-3, the address bus, data bus and control bus can be connected to the
external devices passing through the drivers or receivers, thus making system expansion easy.
Pin No.
Signal Description
1
VDD
+5V power supply
2
VDD
+5V power supply
3
GND
Ground
4
GND
Ground
5
ADO Address and data signal bit 0
6
AD1 Address and data signal bit 1
7
AD2 Address and data signal bit 2
8
AD3 Address and data signal bit 3
9
AD4 Address and data signal bit 4
10
AD5 Address and data signal bit 5
11
AD6 Address and data signal bit 6
12
AD7
Address and data signal bit 7
13
A8
Address signal bit 8
14
A9
Address signal bit 9
15 A10 Address signal bit 10
16
All Address signal bit 11
17
A12
Address signal bit 12
18
A13
Address signal bit 13
19 A14 Address signal bit 14
20
A15
Address signal bit 15
21
GND
Ground
22
GND
Ground
23
RD*
Read enable signal
24
WR* Write enable signal
25
10/M *
I/O or memory select signal
26
SO
Status 0 signal
27
ALE*
Address latch enable signal
28 Si Status 1 signal
29
CLK Clock signal
30
YO
I/O controller select signal
31
A*
I/O or memory access enable signal
32
RESET*
Reset signal
33
INTR
Interrupt request signal
34
INTA
Interrupt acknowledge signal
35
GND
Ground
36
GND
Ground
37
RAM RST
RAM enable signal
38
NC
No connection
39
NC
No connection
40
NC
No connection
Table 4-3. System Bus Pin Assignments