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Condition Code Handling Disclosure Number: IPCOM000067923D
Original Publication Date: 1979-Oct-01
Included in the Prior Art Database: 2005-Feb-20

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Berglund, NC Kempke, WG Richardson, WC Schardt, TL [+details]


Computer systems having one instruction set which is interpreted by another instruction set require the ability to form condition codes for the computation-type instructions of both instruction sets. Interpreting the computation-type instructions consists of performing the indicated operation in an arithmetic and logic unit (ALU) and setting a condition code. If the instruction set includes instructions for performing signed binary arithmetic, then the carry out of the next to the high order bit position must also be known in order to set the signed binary condition code. Without a next to high order carry indication, extra central processing unit (CPU) cycles are needed to obtain information for forming the condition code.