Mera Elzab 7951 OM

This device was probably designed to be compact, simple and cheap, as it uses only 74 logic and no (V)LSI circuits. It was used in Polish Railways to communicate points of sale with computer systems. Its features aren't high-end: 40 characters in a line and 12 lines could be displayed, the only port is one serial port, keyboard is not much comfortable, and case is made of quite thin plastic covered in white paint. Speaker was built-in and made a sound each time key was pressed. Fortunately, there was a volume trimmer.
There were also some versions with amber CRT, but my unit is the most popular device with green one.

Manufacturer: Mera-Elzab

Model 7951OM
Year: 1987
Memory: 1KWord (6-bit word) display memory
Display: Internal CRT
Keyboard: Internal, parallel connection
Main port: Serial port?


Additional ports: None



Peripherals in collection:
 - None


Unfortunately my unit doesn't work, it displays garbage on screen and even doesn't blink cursor. Timing seems to work as picture is generated and display memory is thrown, display memory itself is also good, but something must be wrong with TTL logic chips... yes, 90% of mainboard.

7951OM is a very basic device, which has a logic to generate cursor, feed character generator with characters from port and feed port with characters from keyboard. Display generator uses 2716 EPROM, but it's made pin-compatible to MCY7304NAB ROM. It uses six 1Kbit memory chips to store screen contents (64-character table, uppercase only), but half is used, as it has 40x12 character mode.
Power supply unit is prone to overheating, there are 2 transformers in a steel cover.