Abstract: A local station and a central computer subsystem remotely located from each other are interconnected by a transmission system, such as a telephone network, so that a medium containing visual data can be read in the vicinity where the cart is made, but automatically analyzed by a computer at the central computer subsystem. The local station includes an optical reader device for reading the medium and converting the visual data contained thereon into numerical data in the form of binary electrical signals. The binary electrical signals are compressed by a hardware compressor circuit and a software compressor program so that the transmission time for transmitting the data to the central computer subsystem is reduced. Once the data is transmitted to the central computer subsystem, an analysis of the data is made after any desired modifications of the data have been made through a graphics terminal.

Abstract: A high-speed interface for use between a computer having a Unibus data transmission system and a Tektronix graphics terminal includes elements for converting pairs of coordinate words from the host computer into five seven-bit bytes usable by the Tektronix graphics terminal. The interface is capable of emulating a standard interface device and is also capable of cyclically refreshing the Tektronix graphics terminal so that it can operate in a write-through mode.

Abstract: A data compressor includes circuit elements for counting the number of bytes transmitted in a binary bit stream and further includes storage circuit elements for temporarily storing each byte transmitted in the stream and the corresponding byte count of each byte. The data compressor also includes combinational logic control circuitry for detecting when one of the bits in a temporarily stored byte has a predetermined logic value and for generating a retain data control signal for signalling that the byte contains data desired to be retained.