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Rotation of Register Contents

IP.com Disclosure Number: IPCOM000091955D
Original Publication Date: 1968-Jul-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Husson, SS: AUTHOR [+2]

Abstract

The left and right halves of a register in a computer can be interchanged, i.e., rotated, under the control of a rotate pulse RP. In a computer which generates several clock pulses T0...Tm within a CPU cycle, assume that rotation begins at time T5. Only the clock pulses T5...T10, those concerned with rotation, are shown.

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Rotation of Register Contents

The left and right halves of a register in a computer can be interchanged,
i.e., rotated, under the control of a rotate pulse RP. In a computer which generates several clock pulses T0...Tm within a CPU cycle, assume that rotation begins at time T5. Only the clock pulses T5...T10, those concerned with rotation, are shown.

The system proceeds in the normal mode in each cycle starting with clock pulse T0. Register R is arranged to begin anticipating the rotate mode and begin preparing for the shifting operation at T5.

At T5, the auxiliary register Rx, which is half the size of register R in width, is reset. At T6 the contents of the right half of the register, Rn...R2n-1, are transferred to the auxiliary half register Rx. By the end of the T6 pulse, the machine either continues the operation in the normal mode, i.e., the normal T7...Tm sequence of pulses is generated, or switches to the rotate mode by issuing a RP. This stops the normal clock and starts the auxiliary clock that generates the rotate pulses to control the balance of the CPU cycle. The number of pulses and the duration of each pulse can be different from those that would be generated to control the machine through the balance of the CPU cycle in the normal mode.

Assume that by the end of T6 RP is up. At this point, the contents of register Rr have been transferred to Rx, auxiliary half word. The T7 pulse resets Rr. The contents of R1 are Anded with T8 and RP to permit the...