Browse Prior Art Database

Fast Sequencing Loop for Computer Control

IP.com Disclosure Number: IPCOM000096230D
Original Publication Date: 1963-Feb-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Schlaeppi, HP: AUTHOR

Abstract

The micro-address decoder DT, which is continually rolled by both address register AR and condition register CR, allows conditional branching to one of a set of alternative microinstructions. This is within the course of the same sequencing loop without loss of machine cycles.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 62% of the total text.

Page 1 of 2

Fast Sequencing Loop for Computer Control

The micro-address decoder DT, which is continually rolled by both address register AR and condition register CR, allows conditional branching to one of a set of alternative microinstructions. This is within the course of the same sequencing loop without loss of machine cycles.

Fast sequencing from a microprogrammed control requires that the current machine state M(i) be capable of modifying the control state S(i+l). This is the immediate successor of the current control state S(i) which established M(i). The subscripts indicate successive machine cycles. Fast sequencing also requires that the number of levels of switching in the control loop CS-AR-DT be minimal.

If the circuit speed in the data flow paths is the same as that in the control loop, the first requirement necessitates that the control of microinstruction branching effected by M(i) be superimposed on the decoding of the micro-address. This and the second requirement can be fulfilled by this arrangement shown, where some of the control levels of decoding tree DT are split into two or more sections. One section of each split level is controlled from micro-address register AR as usual. The other part or parts is controlled by the machine state as represented by condition register CR. The remaining levels of DT are controlled from AR alone.

The microinstructions emanate from control store CS. The function part of a microinstruction actuates the gates in the machine...