Entrex 480 Data/Scope: The MM5240: Understanding the operation of the Entrex/Nixdorf Data/Scope Keystation

MM5240 Datasheet

AN ALPHA-NUMERIC CHARACTER GENERATOR FOR A COMPUTER DISPLAY -

A Thesis (from 1969!)

Power Supply Schmetics

Motorola Monitor-TV Chassis Schmetics

Entrex Data/Scope Motherboard Schmatics

Just Terminal Board 4 Schematics

The best description I've come across for how these terminals work:

RaymondHng [Reformatted by me for ease of understanding]

This is not a dumb terminal. It is dumber than a dumb terminal. It is a data entry key station as part of a key-to-disk system.

I use to work on a competing product, the UNIVAC 1900 CADE (Computer-Assisted Data Entry) system.

Unlike dumb terminals that have some logic of encoding key strokes into ASCII characters, sending the ASCII characters to the computer, receiving ASCII characters from the computer, storing the ASCII characters in its internal RAM, and displaying the ASCII character on the screen, data entry key stations have no ASCII encoding ability and no internal RAM storage.

A portion of RAM on the central computer serves as storage for each key station's display.

1) Pressing a key sends a key scan code to the central computer.

2) The central computer encodes the key scan code into EBCDIC characters that are stored on a disk drive.

The central computer can lock the keyboard or unlock the keyboard.

It can shift the keyboard to numeric or alphabetic mode.

It can make an electronic click sound on the key station's speaker when a key is pressed or make no sound when a key is pressed which indicates the keyboard is locked.

It generates a low-tone beep on the key station's speaker which indicates a record is complete or generate a high-tone beep and flash the screen when the operator presses an invalid key.

The key-to-disk system is used for high-speed heads-down data entry where data entry operators enter data from source documents that are grouped in batches. A second operator re-enters the data from the same source documents to verify the data entered by the first operator.

After all the batches of source documents are verified for accuracy, a data entry supervisor writes the verified data as EBCDIC characters on 9-track magnetic tape which is then brought over to a mainframe computer for input processing.

The supervisor can generate reports from the central computer by having it keep track of each operator's productivity in key stroke speed (I use to average 18,000 keystrokes per hour), key strokes inputted, records inputted, errors created, etc.

These key stations cannot be used as a terminal connected to a computer with an RS-232 serial cable. It has no internal logic to output or input ASCII characters..