Philips PM2519 - Page 37

2.4.5.
2-21
Control inputs
The ten function switches, when selected, provide a —5 V supply to one of the inputs of the microcomputer.
The microcomputer reads a bit pattern on port 0 and knows which range is selected.
The mode switches (push-buttons) are connected to a HEF 4532 an 8-input priority encoder. This encoder
gives a binary bit pattern on the output and is also supplied to the microcomputer.
1709
it!
Tt
ren ane
“it
*
Tr
C1704
~ 1703
¢1702
C1701
TP 1002 !
7 cio |
1700 = C1709
ton
poe ee ee
x3001
7 |
y, $3005
Oe oat —5 l
UP
5 9 * aA” $3004
6 6 DOWN
i A 45003
AUTG
7453002
1
€ ON/OFF
| $3008
RCL
1 > 4 $3007
dB
2 $3003
———af 14 Ao l
a
7493008
i)
\ Vv I
ary xr 2
D3800) Sz] Siz] Siz
HEF 4532 Sle] Shin} Slim
\ +—+ i
et BEEPER
nq a |
1 YV |
(ORE enc pe ayer ey |
$1413
840705
Fig. 2.16. Switch decoding