Browse Prior Art Database

Enhancement of Move Along Instruction with Store In Cache Using Castout Buffer

IP.com Disclosure Number: IPCOM000049089D
Original Publication Date: 1982-May-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 2 page(s) / 27K

Publishing Venue

IBM

Related People

Schwengler, MO: AUTHOR

Abstract

The 'Move Long' (MVCL) instruction is used frequently to clear larger portions of storage, e.g., to 8 K bytes . For a 'store in cache' machine this sets large portions of the cache 2 to meaningless values. Eventually these lines have to be 'castout' if their entry is required for other references.

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 89% of the total text.

Page 1 of 2

Enhancement of Move Along Instruction with Store In Cache Using Castout Buffer

The 'Move Long' (MVCL) instruction is used frequently to clear larger portions of storage, e.g., to 8 K bytes . For a 'store in cache' machine this sets large portions of the cache 2 to meaningless values. Eventually these lines have to be 'castout' if their entry is required for other references.

The enhancement described is for intermediate size IBM System 1370 machines which have a 'castout' buffer 4 but do not have an 'intelligent' Storage Controller (SC). The idea would allow s simple cache to SC interface (no special commands to SC required).

The idea is to force the padding character field into the 'castout' buffer 4 for the MVCL instruction execution.

When the processor microcode determines the case of an MVCL instruction with the second operand shorter than the first one (which results in storing of the 'pad' character in Main Storage (MS)), the following actions take place:
1. Check if one or more cache lines have to be padded.

If no total line approaches go to 7.
2. If line is in cache, invalidate line in cache directory.
3. Force 'castout' buffer to pad character field.
4. Load address register for MS addressing.
5. Transfer 'castout' buffer as normal data transfer.
6. Decision by microcode if another line has to be padded.

Yes approaches go to 2

No approaches go to 7 (Steps 5 and 6 can be

overlapped.)
7. Normal continuation.

In the present process design the MVCL instructi...