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Browse Prior Art Database

Programmable Main-Storage Card Map

IP.com Disclosure Number: IPCOM000102544D
Original Publication Date: 1990-Nov-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 4 page(s) / 132K

Publishing Venue

IBM

Related People

Eikill, RG: AUTHOR [+3]

Abstract

A solution involves the ability of the operating system to load a Memory Configuration Register with values which will cause the hardware to logically swap the memory cards. Starting address and size are loaded for each card slot.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Programmable Main-Storage Card Map

       A solution involves the ability of the operating system
to load a Memory Configuration Register with values which will cause
the hardware to logically swap the memory cards. Starting address and
size are loaded for each card slot.

      Memory Configuration Register (MemConFig) is loaded with an
encode which tells the size of each memory card and its starting
address.  This is known to the operating system after performing an
operation to read the Card ID from each memory card installed in the
system.  If no card is installed, the register is loaded with a value
to indicate that the slot is empty.  After the operating system knows
which card is in which slot, it loads the MemConFig with specific
values to indicate the desired configuration for testing.

      Main store is then tested by the operating system to determine
if all of the installed memory is good.  The operating system needs
several large areas of contiguous good memory.  One of these areas
must begin at the beginning of a card.  It is, therefore, necessary
to find one card which has that area free of multi-package errors.
Once this is done, the operating system will arrange the available
cards in an order which will allow for all good memory to be in the
areas needed and to allow for maximum performance.

      Since both the starting address and size are loaded into the
MemConFig, any slot can start at any address, and each slot can
support any size card.

      The heart of this invention lies in the address formatter.
Using a starting address and size is a common way to solve the
problem, but is very slow and inefficient. A lot of logic is needed
to determine the offset into a card for a given address.  Here lies
the significance of this invention.  In a high-performance processor,
we cannot wait for a cycle to reformat the address into a command to
the memory card.  By putting a few restrictions on the possible
memory configurations, we can get away with very few levels of logic
format to the address.

      The only restriction put on the memory configuration is that
the starting address of each memory card must be a multiple of the
card size.  It is possible that due to bad areas of main store and
the need for error-free space by the operating system that we cannot
configure the system without a gap in the addressing.  This invention
is capable of handling this, and another advantage is that only one
gap will ever be needed independent of the number or size of memory
cards installed.

      Fig. 1 shows the memo...