Scan Result Descriptor (SRD)/OP=91

Format

OP AFBF

OP = 91

AFBF Low order four digits of an absolute address in memory. The high order three digits are assumed to be zero. Indirect field length can be specified.

Note This is a privileged instruction. The base must equal zero.
Note This instruction is obsolete.

Function

The address specified is assumed to point to a 16-bit result descriptor area. The first bit of this area is examined and:

  • If it is equal to zero (no result descriptor present), the four digits (link address) immediately following the descriptor area are examined and
    • If they are 0000, the comparison toggles are set to EQUAL and the instruction terminates (no descriptor found)
    • If they are not zero, they replace the original address value and the operation is repeated.
  • If it is equal to one (result descriptor present), the address of the descriptor area is stored into index register one (IX1). The next bit is examined, and the comparison toggles are set HIGH if it is a zero, otherwise they are set LOW. The instruction then terminates.

The interrupt toggle is set to zero by this instruction.

If the initial address specified in AFBF is equal to zero, the comparison toggles are set to EQUAL, index register one (IX1) is unchanged and the instruction terminates.

Comparison Flags

  • HIGH A result descriptor was found and the exception bit was set.
  • LOW A result descriptor was found and the exception bit was clear.
  • EQUAL No result descriptor was found.

Overflow Flag

The overflow flag is not changed by this instruction.

instructions/srd.txt · Last modified: 2018/03/10 15:37 (external edit)
 
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