circuit for the address of a datageheugen datawoorden in a datavisietoestel.

摘要

1529098 Cathode-ray tube display data processing SIEMENS AG 24 Sept 1976 [25 Sept 1975] 39645/76 Heading H4T A circuit for use in a data display device to supply data store addresses of data words, e.g. DZ1, DF1, DZ2, ... DZ5 assigned to representable characters Z1, Z2, ... Z5 and to "field control" characters e.g. DF1, DF2, DF3, comprises an address register BAR for storing an address word BA which represents the position of a representable character Z the data word of which, or of a field control character F pertaining thereto, is to be addressed, a second address register DAR for storing a second address word DA representing the address of the data word which is to be addressed relative to that of the corresponding representable character, an address counter A which emits a data store address AD and whose count increases by 1 after each read-out, a counter ZZ which counts read-out of data words assigned to representable characters, and means including a subtractor SUB for modifying the count of address counter A by the address DA stored in the register DAR in the event of identity, established by a comparator VG, of the address word BA and the count of the character counter ZZ, thereby to form the address of the data word to be addressed. As shown, field-control character F1 pertains to, and determines the nature of, representable characters Z2, Z3, and F2, F3 pertain to Z4, Z5 etc. The addresses A0 . . . A7 of characters F and Z are stored in the same data store. If Z4 is to be addressed, BA=4 and DA=0. Switch SS2 issues, upon each read-out, a signal LE to the data store which returns SZ = 1 when the address is that of a control character F and SZ = 0 when the address is that of a representable character Z. Decoder DC issues a 1 for each character Z and these are counted in ZZ. When the count of ZZ is 4, VG issues S8 = 1 (no signal otherwise) and subtractor SUB subtracts DA = 0 from the count corresponding to A6. If DF2 is to be addressed, BA = 4 and DA = 2. Thus, DA = 2 is subtracted from the address A6, so that an address A4 is issued to the store by the address counter A.