DATA ENTRY/DATA RETRIEVAL TERMINAL

摘要

DATA-ENTRY/DATA-RETRIEVAL TERMINAL A data collection terminal for displaying data and for transmitting to and receiving data from a central station has a keyboard and facility for peripheral devices for entering data. A numeric readout is provided and may be used if desired. Further, a grid of light emitting diodes (LED's) is provided. A removable mask may be placed over the LED's so that each LED corresponds to a specified field of terminal operation, depending upon the particular use to which the terminal is put. Function keys and a set of numeric keys are provided, the former for causing operations to be performed and the latter for entering numeric data. The terminal is controlled by a microprocessor and associated circuits, particularly including a read-only memory (ROM) which is configured to control the microprocessor in a desired manner to provide the terminal with a specified configuration to perform a particular task or tasks. Tutorial circuitry is provided for optionally displaying sequential prompting steps on the numeric readout and/or the LED grid to permit an operator of the terminal to follow the prompting steps for proper entry of a desired transaction. Circuit means are also provided for identifying data as to its peripheral device source or keyboard source as it is written into temporary storage in consecutive memory locations irrespective of the source, the data being reidentified as to its source when read out and transmitted to the central station. The numeric readout in the preferred embodiment is a vacuum fluorescent display whose filament is activated by a DC potential. To compensate for the progressive voltage drop along the DC filament, the characters are activated for varying lengths of time depending upon their position within the vacuum fluorescent display, providing apparent equal brightness to each character displayed.