Browse Prior Art Database

Message Control for Computer Output Display

IP.com Disclosure Number: IPCOM000080794D
Original Publication Date: 1974-Feb-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 3 page(s) / 65K

Publishing Venue

IBM

Related People

Hartmann, FM: AUTHOR [+5]

Abstract

This message control system employs special order codes which permit repetitive, identical characters emitted on the output of a computer to be displayed at a remote station by only a few instructions, thus reducing the message preparation time, the memory requirements, and making more efficient use of the channel between the computer and the display, for example, for sharing the channel with other output devices. The display device is of the regenerative type, in which the data stored in a message buffer is continuously displayed on an image screen.

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Message Control for Computer Output Display

This message control system employs special order codes which permit repetitive, identical characters emitted on the output of a computer to be displayed at a remote station by only a few instructions, thus reducing the message preparation time, the memory requirements, and making more efficient use of the channel between the computer and the display, for example, for sharing the channel with other output devices. The display device is of the regenerative type, in which the data stored in a message buffer is continuously displayed on an image screen. The control system permits the same character to be stored in successive cells of the message buffer, and thus to be displayed in successive character positions in response to appropriate orders, by specifying only the type of character and the last display position address (see, RTA-order, for example).

The addressing device, positioning the character identifying signals in the buffer, is advanced to the last position address specified and caused to deliver a succession of signals each representing the respective, identical character. The last position address as specified in the order is stored in an address store register. This address is continuously compared with the actual contents of the address counter, which controls the writing operation into the buffer. The address counter is advanced one position at a time. When the contents of both the address store register and address counter match, a signal is delivered to message control and repetitive inscription of the same character into successive buffer positions is terminated.

Figs. 1 and 2 show a succession of information segments 1 - 26 and 27 - 35, representing typical data streams of the message control system. The segments consist of several bytes which represent order codes (e.g., SBA), addresses (e.g., A1/A2), characters to be displayed (e.g., NAME:), characters to be repeated with suppressed display (NULL), etc. The bytes labeled SBA (Set Buffer Address), SF (Start Field), PT (Program Tab), RTA (Repeat to Address), and EUA (Erase Unprotected to Address) represent special order codes used in the message control system. An address always consists of two bytes (A1 and A2).

The SBA-order is a three-byte order specifying a new buffer address, from which write operations are to start or continue. It can be used to write data into various buffer areas. It can also precede another order in the data stream to specify the starting address for a PT, RTA or EUA order, or to specify the address at which an attribute byte is to be stored by an SF-order.

The SF-order is a two-byte order; the second byte is an attribute character (AT). ATs are primarily used to define protected (P) or unprotected (U) fields in the display image, and also to control character display (display/nondisplay, intensified display, etc.). A P-field is protected from modification by an operator, whereas a U-field is av...