Tester 297 being used in the street, A blue hard hat should always be worn.
The Tester 297 is a handheld programmer for the GPT/Plessy type payphones
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 NEC D7225 LCD driver Chip see http://www.alldatasheet.com/datasheet-pdf/pdf/7014/NEC/UPD7225G00.html
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.