Patent GB-1394881-A (GB)
Title: Method of and apparatus for displaying a plurality of information display segments on a cyclically refreshed display device
IPC: G06F3/14
Filed: 1972-05-24
Abstract: 1394881 Control of displays BUNKER RAMO CORP 24 May 1972 [8 Sept 1971] 24513/72 Heading G4H [Also in Division H4] In a multi-mode segmented display, display devices 14A-14N (e.g. CRT's), are supplied with information from an addressable magnetic core memory 18 under the influence of a control unit 40 connected to keyboards 16A-16N. Three types of data may be displayed at 14: common data, which is the same for all displays and may not be altered by the operator (e.g. ticker, newswire); quote-type displays, which permit the operator to select the particular item of information in which he is interested but in which he may not make changes; and MIS- type data over which the operator has full control. The display can accommodate 24 rows of 48 characters each composed of a 5 x 7 matrix of selectively energized "points"; the rows are grouped into eight segments of three rows each, and these segments may be grouped in different ways to yield four different "modes" of which Fig 2, is an example. An "entry marker" (EM) may also be displayed by energizing all 35 points of a matrix: this indicates the display position where new information is to be displayed or where editing functions may begin. Memory 18, Fig. 6, is divided into a buffer area 18A (for temporary storage), N control areas 18B, and areas 18C, 18D containing common data and MIS or quote-type information respectively. Each area 18B, Fig. 8, comprises an area 20 containing the segment addresses in the memory for the segments being used to refresh each of the 8 segments of its display 14, an area 22 containing an indication of the position of the EM (and the segment address thereof), an area 26 containing screen format words to indicate the types of information in each segment for the various modes, and an area 28 containing the segment addresses for all four modes and from which the appropriate addresses for 20 are taken. The information in 18 is read-out from 18C or 18D under the control of a memory address circuit 32: the N addresses from each segment in turn are fed from area 20 to N device registers 46 from where they are fed to circuit 32 together with the output from a word counter 44 which indicates the word position in each segment 18C or 18D (each addressable position in 18 has a two-character word address). Registers 46 thus contain the segment addresses in 18C or 18D of the segments being read-out to refresh the displays 14. When all the words for the N first segments have been read-out, unit 40 generates an output 38 to cause the second N segment addresses in 20 to be read-out via 72 to registers 46. The output from 18C, 18D is converted from ASC11 to 35-bit video characters in a generator 84 then fed by a multiplexer 90 to the appropriate displays 14. The contents of the N areas 22 are meanwhile fed to N EM-registers 98 for comparison with clock signals: when the display for a given device is at the position containing the EM for that device, generator 104 causes the EM video signal to be fed to multiplexer 90. The operator may change the display mode by signalling unit 40 by means of keyboards 16, Fig. 7 (not shown), a detailed description is given of how segments containing related information may be "chained" together and the EM "homed" on the first segment of the chain; how the EM may be placed in the first character position of the first segment which does not contain a common display (if they are all common, then no EM is displayed); and how the type of display appearing in each of the segments may be determined so that the EM may be positioned in the first character position of the first segment containing the desired type of information. A particular memory segment may be used to store different types of information for different display modes: if a particular memory segment is not being used to display a different type of information in a newly selected display mode then the information may be "saved" and updated during the period when it is not being displayed. A detailed description is also given of one possible embodiment of control unit 40 (Figs. 15A, 15B, not shown).