Browse Prior Art Database

Double Usage of Read Only Storage

IP.com Disclosure Number: IPCOM000092548D
Original Publication Date: 1966-Dec-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

Kevill, JF: AUTHOR

Abstract

Read-only storage ROS employing unit records provides an important aspect of data processing control. An arrangement is shown for reducing the number of data bits per ROS module by obtaining double usage from certain bits. A special bit position Phi and associated logic, comprising gates 11 and 12 and Inverter 13, switch certain B Field positions between the two uses.

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Double Usage of Read Only Storage

Read-only storage ROS employing unit records provides an important aspect of data processing control. An arrangement is shown for reducing the number of data bits per ROS module by obtaining double usage from certain bits. A special bit position Phi and associated logic, comprising gates 11 and 12 and Inverter 13, switch certain B Field positions between the two uses.

In one type of operation, A Field and B Field are decoded in A Decode and B Decode to gate selected registers 18 to provide operands on the A and B busses, respectively, to arithmetic logic unit ALU. The D Field is decoded in D Decode to gate a selected register 18 into which the result from ALU is placed. To operate in this fashion, the bit Phi of such a unit record is 0, blocking gate 12. Inverter 13 gates 11 the output of B Decode.

The alternative operation of the apparatus is to decode the A and D Fields as before, but to transmit a constant on the B bus to ALU rather than the output of the register. Thus, the bit Phi on unit records operating in this fashion is 1, opening gate 12 and blocking gate 11. The data from B Field and K Field are combined in K Assembler 23 and gated by gate 12 on the B bus to ALU.

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