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3
J5
This connection may be used for the level conversion for a secondary serial. The TI and TO connections are
the TTL input and output to the level converter while the 2I and 2O connections are the RS-232 level input and
output. The picture on the preceding page shows the supplied SIP socket strip is installed in this connection.
This facilitates connection by inserting wires (24 ga. maximum) into the sockets.
Assembly Procedure
The assembly sequence isn’t critical so you may perform the steps in any convenient order. You may wish to
use a socket (not included) for U1 and possibly for U2 as well. Doing so for U1 will make it easier to substitute a
different EEPROM should you so choose. Note carefully the orientation marks for these ICs. Pin 1 of each has
a square pad while the remaining ones are round. U1 and R3 may be omitted for ZX devices that do not need a
serial EEPROM.
All resistors are the same value – 10K. The inductor, which looks similar to a resistor, is not mounted on the
board. Rather, it is connected between +5 and pin 30 of the ZX-40/ZX-40a as shown in the photo on the
previous page.
There are three different capacitor values in the kit. C1 and C2 are 27pF capacitors. They are marked simply
with “27”. C3 through C6 are 0.1uF capacitors, marked with “104”. C7 is a 0.01uF capacitor, marked with
“103”. The remaining two capacitors, one 0.1uF and one 0.01uF, are filtering capacitors should be connected
directly across pins of the ZX-40 on your breadboard as shown in the photo on the preceding page. The 0.1uF
should be connected between pins 30 and 31 and the 0.01uF should be connected between pins 31 and 32.
Pin 31 should also be grounded.
The transistor Q1 must be installed with its flat face toward R3. The crystal, X1, may be installed in either
orientation.
If you plan to solder square pins to the board to connect the Module to a solderless breadboard, the simplest
way to do so is to insert the square pins for J1, J2 and J3/J4 into the solderless breadboard and then place the
board over the pins and solder them in place. This ensures that the pins are not misaligned. Whether you use
J3 or J4 depends on how you configure the power and ground busses on your solderless breadboard.
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