More Strobe Lines !
After the 8 data lines are hooked up there are only 4 more output lines available to be used as strobe lines. Although this is enough to control some PTS symthesizers, you will need more lines for some other models or if you intend to control multiple PTS units. There are several options to generate more strobe lines.
1 - Install another printer port.
2 - Use an address decoder to expand the 4 lines that are available.
I used an address decoder as I wanted to save the other printer ports for controlling other devices.
Using the remaining 4 output lines a 7442 can be used to generate 9 strobe lines. This is enough to control two PTS-160 or a PTS-500 and a PTS160.
A 4515 CMOS / 74154 TTL device can be used to generate 15 strobe lines. This can control 3 PTS-500, 3 PTS-160 or any combination of these.
The 7442 appears to be more readily found in the junk box but if you are buying your decoder chip new look for the CD4515 / MC14515. The 4515 is NOT an expensive chip. Many suppliers sell this chip for as low as $0.25 each.
+5 vdc to power the decoder is available on Pin 48 of the parallel remote plug on the back of the PTS synthesizer.
7442
TTL
1-of-10 inverting decoder/demultiplexer
This will
generate 9 strobe lines from 4 address lines.
S0,S1,S2,and S3 go to the 4 output lines from
the computer.
/Y1 through /Y9 are the 9 strobe lines to the
PTS.
/Y0 is reserved for the 'OFF'
state.
This
chart has NOT been verified!
+----------+
/Y0 |1 16| VCC
/Y1 |2 15| S0
/Y2 |3 14| S1
/Y3 |4 13| S2
/Y4 |5 7442 12| S3
/Y5 |6 11| /Y9
/Y6 |7 10| /Y8
GND |8 9| /Y7
+----------+
|
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CD4515, MC14515, CMOS 1-of-16 inverting decoder/demultiplexer with address latches.
This will generate 15 strobe lines from 4 address lines. S0,S1,S2,and S3 go to the 4 output lines from the computer. /Y1 through /Y15 are the 15 strobe lines to the PTS. /Y0 is reserved for the 'OFF' state Note: Pin 23 /EN must be grounded to enable the chip! Pin 1 LE should be tied to (high) VCC at pin 24. This chart has been verified!
+----------+
LE |1 24| VCC
S0 |2 23| /EN
S1 |3 22| S3
/Y7 |4 21| S2
/Y6 |5 20| /Y10
/Y5 |6 19| /Y11
/Y4 |7 4515 18| /Y8
/Y3 |8 17| /Y9
/Y1 |9 16| /Y15
/Y2 |10 15| /Y14
/Y0 |11 14| /Y12
GND |12 13| /Y13
+----------+
|
|
74154
This will generate 15 strobe lines
from 4 address lines.
A,B,C,and D go to the 4 output lines from
the computer.
/Y1 through /Y15 are the 15 strobe lines to the
PTS.
/Y0 is reserved for the 'OFF' state.
This
chart has NOT been verified!
+----------+
/Y0 |1 24| VCC
/Y1 |2 23| A
/Y2 |3 22| B
/Y3 |4 21| C
/Y4 |5 20| D
/Y5 |6 19| /G2
/Y6 |7 74154 18| /G1
/Y7 |8 17| /Y15
/Y8 |9 16| /Y14
/Y9 |10 15| /Y13
/Y10|11 14| /Y12
GND |12 13| /Y11
+----------+
Ground G1 and G2 to enable the chip ! |
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