Browse Prior Art Database

Buffer Control Storage

IP.com Disclosure Number: IPCOM000092320D
Original Publication Date: 1968-Dec-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 45K

Publishing Venue

IBM

Related People

Annunziata, EJ: AUTHOR [+2]

Abstract

A high-speed, low-capacity buffer control store BCS 10 is used to contain portions of a control microprogram associated with instructions currently being executed. A low-speed, high-capacity main store MS 11 stores the entire system microprogram along with the system program being executed. Portions of the microprogram are transferred from MS 11 to BCS 10 when needed. Thus, the memory system for the microprogram has the apparent storage capacity of MS 11 but with the speed of BCS 10.

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Buffer Control Storage

A high-speed, low-capacity buffer control store BCS 10 is used to contain portions of a control microprogram associated with instructions currently being executed. A low-speed, high-capacity main store MS 11 stores the entire system microprogram along with the system program being executed. Portions of the microprogram are transferred from MS 11 to BCS 10 when needed. Thus, the memory system for the microprogram has the apparent storage capacity of MS 11 but with the speed of BCS 10.

Look-ahead 12 presenses the instruction stream ahead of the current instruction. This allows BCS 10 to be loaded with the appropriate microprogram, if it is not resident in BCS 10, before the current instruction requiring such program is issued. To determine whether the appropriate microprogram is in BCS 10, look-ahead 12 sends instruction signals to decoder 13. The latter's output includes the address of the first word of the microprogram associated with the particular instruction. This address is placed in a control store address register CSA 14.

From CSA 14, the request is sent to address transform unit 15 that converts the effective address into the appropriate address for reading out BCS 10. Upon receiving such request, unit 15 sends a signal to readout tag storage 16. This storage maps the information in BCS 10. The contents read out of storage 16 are compared by compare circuit 17 with the request to see if the microprogram is resident in BCS 10. If it i...