Browse Prior Art Database

Self Aligning End of Instruction and Next Instruction Load

IP.com Disclosure Number: IPCOM000037818D
Original Publication Date: 1989-Jul-01
Included in the Prior Art Database: 2005-Jan-30
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Ely, JD: AUTHOR [+2]

Abstract

This disclosure automatically loads the next instruction where the instructions have varying numbers of machine cycles, different amounts of dead time at the end of the instruction and occur randomly in time such that a periodic instruction fetch and load may take place.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 75% of the total text.

Page 1 of 1

Self Aligning End of Instruction and Next Instruction Load

This disclosure automatically loads the next instruction where the instructions have varying numbers of machine cycles, different amounts of dead time at the end of the instruction and occur randomly in time such that a periodic instruction fetch and load may take place.

In Fig. 1, a processor (not shown) includes a microcode storage 10 which supplies a macro instruction or control word 12 to a control word register 14. As part of the control word, an End of Microcode (EOM) signal 16 is emanated during the cycle which is the last microcode operation of each instruction. Along with this signal is a NOPCTR signal 17 which includes a value X which represents the number of dead cycles left in the instruction. A timing circuit 18 is activated in response to the EOM signal 16 to supply a disable signal 19 to the control word register 14. The disable signal prohibits any new microcode from being loaded into the register 14. The NOPCTR signal 17 is used to determine the time period between the EOM 16 and the End of Instruction (EOI) 24 which period is a random variable. The NOPCTR signal 17 is loaded into the counter control circuit 20 which automatically loads the signal into a counter/decrementer 22 that counts down from the value X to 0. When 0 is reached, the EOI signal 24 is generated. The counter is turned off by the counter control 20. The EOI signal 24 triggers the timing circuit 18 to send an enable sign...