Abstract: Information from a main data processor is transferred to an auxiliary data processor of the system and is stored in a control file which may be addressed by either a firmware word from a control store or by use of the function code received in an instruction from the main processor. Information in such control file is used for the purpose of addressing main memory. The address for main memory may be incremented or decremented simultaneously as operands are being fetched from main memory for execution.

Abstract: Binary coded decimal operands may be operated on by use of a binary arithmetic logic unit and the result corrected to provide a binary coded decimal result by use of correction logic which is responsive to the result produced by the binary arithmetic logic unit, the type of operation being performed and whether the binary arithmetic logic unit produced a carry as a result of its arithmetic operation on such operands.

Abstract: A control store in a data processor is addressed by means of next address generation logic which includes a first multiplexer utilized to address the control store, which multiplexer has several inputs. One of such inputs is received from a latching mechanism which allows more than one test condition to be simultaneously utilized for addressing the control store on a free flow basis. These test conditions, as well as information from an addressed control word, are utilized in a multiplexed arrangement as one input of the first multiplexer. By use of other inputs of such first multiplexer, the control store may be addressed by use of branch address information, as well as other test condition information. A page register provides the page address, to a plurality of pages included in this control store with the locations in each such page addressed by use of the above noted multiplexer combination.