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212 Part 3 The instruction-set processor level: variations in the processor

Section 1 Processors with greater than 1 address per instruction

13 Compare Magnitudes. g can be relative only to the instruction counter. If ÷ (a ')÷ ³ (b ') the contents of the instruction counter are increased by one as is normally done at the end of each instruction. If (a ') < ÷ (b ')÷ , the contents of the instruction counter is set to g '.

14 Base or Tally. The d digit is ignored. a and b may be relative only to the base counter, g only to the instruction counter. If a ' ³ b ', the contents of the base counter are set to zero and the contents of the instruction counter increased by one as usual. If a ' < b ', the contents of the base counter are set to a ' and the contents of the instruction counter to g '. (Note. The comparisons made here are of addresses themselves, not their contents.)

15 File. b may be any odd number. a and g may be relative only to the instruction counter.

If d = 0, the contents of the instruction counter in creased by one is placed in the g position of (a '), and the instruction counter is set to g '.

If d = 1, the contents of the base counter is placed in the a position of (a '), and the instruction counter is set to g '. In addition, if b = 1, the contents of the base counter is set to zero; if b = 0, the contents of the base counter is not changed.

Transfer of information

16 Read In. The a digit must be 0; the b digit is ignored. If b is in the range 0 to 7 (decimal) or 000 to 007 (hexadecimal) a words are read into the acoustic storage from in put-output station b . The first word read in is placed in g ', the second in g ' + 1, etc. If b is in the range 1024 to 1791 decimal (400 to 6FF hexadecimal), a words are read into the acoustic storage from the drum starting with the first word in the drum block whose address is b . The first word is placed in g ', the second in g ' + 1, etc.

17 Read Out. The a digit must be 0, the c digit is ignored. Starting with (b '), read out a consecutive words from the acoustic storage to input-output station g , if g is in the range 0 to 7 decimal (000 to 007 hexadecimal), or to the drum starting at the beginning of the drum block whose address is g , if g is in the range 1024 to 1791 decimal (400 to 6FF hexadecimal).

16 Alphanumeric Read In. The a digit must be 1; the b digit is ignored. If b is in the range 0 to 7 (decimal) or 000 to 007 (hexadecimal) a characters are read into the acoustic storage from input-output station b . The first character read in is placed in g ', the second in g ' + 1, etc. Each character occupies the six most significant digit positions of the register into which it is read; the other positions are set to zero. This operation may not be used to read words from the drum into the acoustic storage.

17 Alphanumeric Read Out. The a digit must be 1; the c digit is ignored. Starting with (b '), read out a consecutive characters from the acoustic storage to input-output station g ; g must be in the range 0 to 7 (decimal) or 000 to 007 (hexadecimal). This operation may not be used to read words from the acoustic storage onto the drum.

18 Move Tape Forward. (a, b, c and d digits are ignored.) b may be any even number; g must be in the range 0 to 15 decimal (000 to 00F hexadecimal). The magnetic tape at input-output station g is moved forward n blocks where

that is, one plus the integral part of a - 1/8, or the number of blocks that include a words.

19 Move Tape Backward. (a, b, c, and d digits are ignored.) b may be any odd number; g must be in the range 0 to 15 decimal (000 to 00F hexadecimal). The magnetic tape at input-output station y is moved backward n blocks where


that is, one plus the integral part of a - 1/8, or the number of blocks that include a words.

References

CarrJ56. SEAC computer references: AinsE52; AlexS5l; ElboR53; GreeS52, 53; HaueR52; PikeJ52; SerrR62; ShupP53; SlutR5l. DYSEAC computer references: LeinAS4.

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