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Chapter 43 The structure of SYSTEM/360 593

Fig. 5. Eight-bit representation for proposed international code.

Logical operations can also be performed on fields of up to 256 bytes, in which case the fields are processed from left to right, one byte at a time. Moreover, two powerful scanning instructions permit byte-by-byte translation and testing via tables. An important special case of variable-length logical operations is the one-byte field, whose individual bits can be tested, set, reset, and inverted as specified by an 8-bit mask in the instruction.

Character codes

Any 8-bit character set can be processed, although certain restrictions are assumed in the decimal arithmetic and editing operations. However, all character-set-sensitive I/O equipment assumes either the Extended Binary-Coded-Decimal Interchange Code (EBCDIC) of Fig. 4 or the code of Fig. 5, which is an eight-bit extension of a seven-bit code proposed by the International Standards Organization.

Decimal arithmetic

Decimal arithmetic can improve performance for processes requiring few computational steps per datum between the source input and the output. In these cases, where radix conversion from decimal to binary and back to decimal is not justified, the use of registers for intermediate results usually yields no advantage over storage-to-storage processing. Hence, decimal arithmetic is provided in SYSTEM/360 with operands as well as results located in storage, as in the IBM 1400 series. Decimal arithmetic includes

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