Tester 297

Tester 297 being used in the street, A blue hard hat should always be worn.

It contains 2 PCBs, the first has the processor, Eprom, Ram and interface circuitry

It has the same CMOS 8 bit CDP 1802 processor as the Payphone, running with a 2Mhz crystal.

The CDP1802 family of CMOS microprocessors are 8-bit register oriented central processing units (CPUs) designed

for use as general purpose computing or control elements in a wide range of stored program systems or products.

The CDP1802 types include all of the circuits required for fetching, interpreting, and executing instructions which have

been stored in standard types of memories. Extensive input/output (I/O) control features are also provided to facilitate system design.

At the bottom left of the processor board is a ZIF socket, with nothing in it.

At the top centre is an empty Blue 20 pin DIL socket marked SK1

The back of the micro board has a number of "mods"

At the very top of the board is a strip of 15 contacts that connect with the Display and Keypad PCB

The Back of the this board is fairly plain, the back of the switch contacts and LCD dirver ship can be seen.

The µPD7225 is a software-programmable LCD (Liquid Crystal Display) controller/driver. The µPD7225 can be

serially interfaced with the CPU in a microcomputer and can directly drive 2, 3, or 4-time division LCD. The µPD7225

contains a segment decoder which can generate specific segment patterns. In addition, the µPD7225 can be used to

control on/off (blinking) operation of a display.