Mask Controlled Byte Handling
Original Publication Date: 1978-Feb-01
Included in the Prior Art Database: 2005-Feb-20
The insert character under mask (ICM) and compare logical character under mask (CLM) instructions specified for the IBM System/370 provide great flexibility for moving and comparing data bytes contained in storage to those bytes contained in a general purpose register (GPR). The degree of flexibility architected into these instructions has resulted in a high usage of them by software. However, the nature of these instructions is such that special implementation problems are presented which obstruct their processing. On some systems, the ICM and CLM instructions were implemented in a relatively slow manner with the bytes being manipulated one at a time; to do otherwise would have required special hardware in the data flow.