Address data converter

Abstract

An address data converter for converting binary row address information and binary column address information corresponding to data character display locations of a CRT display device having a row/column display field to binary absolute address information. The address A of a given character display location in a typical display field including a plurality of rows each having 80 character display locations can be represented by A=C.sub.A +80R.sub.A, where C.sub.A is the column address of the display location and R.sub.A is the row address. Since the number 80 in the above expression cannot be represented by an integral power of two, it is ordinarily necessary to provide more than 80, for example, 128, character storage locations in memory for each display row of the CRT display device. In accordance with the present invention it has been recognized that the above expression can also be represented by A=C.sub.A +16R.sub.A +64R.sub.A, in which the number 16 and 64 can be represented by integral powers of two. In deriving a value of A, four full adders included in the address data converter of the invention are employed to first derive a sum of C.sub.A +16R.sub.A and to then add this sum to 64R.sub.A, the total sum representing absolute address information. The absolute address information may then be used to address data characters stored in memory in successive groups of 80 data characters, rather than 128 data characters, thereby reducing overall memory requirements.

Dependencies are inferred from the claim text.