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Microprogram Control for Loading Microprogram Storage

IP.com Disclosure Number: IPCOM000079937D
Original Publication Date: 1973-Oct-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 62K

Publishing Venue

IBM

Related People

Phillips, BR: AUTHOR [+3]

Abstract

A system is shown for loading a read/write control store, using a read only control store microprogram to control the loading.

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Microprogram Control for Loading Microprogram Storage

A system is shown for loading a read/write control store, using a read only control store microprogram to control the loading.

A single microinstruction contains all data flow and main store control operations. This microinstruction is latched into the control store output register (CSOR) 12 and control store address information is presented to control store 10 for storing operations, rather than reading out further microinstructions. The operation continues until the correct number of control store words have been loaded, at which time the control store addressing reverts to normal operation.

Control store addresses are a subset of main store addresses.

The A register 14 and the B register 16 are loaded with a starting main store or control store address, word count and incrementation deltas.

When the load word microinstruction is read from control store 10, it is latched into CSOR 12 by the Load R/W latch 20 and Load R/W line 21. Load R/W latch 20 also causes control store addresses to be derived from ALU 18 rather than from CSOR 12 and logic 24 by enabling gate 26 and disabling gate 28, the outputs of which are combined in OR circuit 30 and presented as address lines to control store 10.

The system then operates as follows:

The contents of the A register is added to the contents of the B register which result is then stored in the B register. This updated address information is then used to address main sto...