公开(公告)号：DE68923433T2

公开(公告)日：1996-03-07

申请号：DE68923433

申请日：1989-11-30

Applicant: IBM

Inventor： BUSH GREGORY FREDERICK ,  KEENER DON STEVEN ,  MOREL JEANNE ELLEN ,  VOORHEES RICHARD W

IPC: G06F12/06

Abstract: In order to more effectively use read only memory space of a personal computer system, ROM code is selectively located or mapped to either an address boundary which is an even or odd integer multiple of one half the capacity of the read only memory device in which the ROM code is stored. The ROM code is stored in the read only memory device in two fields. In a first field, the ROM code is broken up into two segments, and the first segment precedes the second segment. In the second field, the same two segments are stored, but the second segment is stored preceding the first segment. A register, for storing page select bits, provides an input to an address decoder and an input to an adder, which adds unity to the contents of the register and provides its output to the address decoder as well. Accordingly, the address decoder will respond to either the page which is identified by the page select bits or the page following the identified page. The LSB of the page select bits is used in addressing the read only memory device to select between the first field (selected when the LSB is zero) or the second field (selected when the LSB is unity).

公开(公告)号：DE68923433D1

公开(公告)日：1995-08-17

申请号：DE68923433

申请日：1989-11-30

Applicant: IBM

Inventor： BUSH GREGORY FREDERICK ,  KEENER DON STEVEN ,  MOREL JEANNE ELLEN ,  VOORHEES RICHARD W

IPC: G06F12/06

Abstract: In order to more effectively use read only memory space of a personal computer system, ROM code is selectively located or mapped to either an address boundary which is an even or odd integer multiple of one half the capacity of the read only memory device in which the ROM code is stored. The ROM code is stored in the read only memory device in two fields. In a first field, the ROM code is broken up into two segments, and the first segment precedes the second segment. In the second field, the same two segments are stored, but the second segment is stored preceding the first segment. A register, for storing page select bits, provides an input to an address decoder and an input to an adder, which adds unity to the contents of the register and provides its output to the address decoder as well. Accordingly, the address decoder will respond to either the page which is identified by the page select bits or the page following the identified page. The LSB of the page select bits is used in addressing the read only memory device to select between the first field (selected when the LSB is zero) or the second field (selected when the LSB is unity).

公开(公告)号：BR9201997A

公开(公告)日：1992-12-29

申请号：BR9201997

申请日：1992-05-27

Applicant: IBM

Inventor： KEENER DON S ,  MOORE GRGORY J ,  VOORHEES RICHARD W

IPC: G06F13/00

公开(公告)号：NZ231639A

公开(公告)日：1992-03-26

申请号：NZ23163989

申请日：1989-12-05

Applicant: IBM

Inventor： BUSH GREGORY FREDERICK ,  KEENER DON STEVEN ,  MOREL JEANNE ELLEN ,  VOORHEES RICHARD W

IPC: G06F12/06 ,  G06F9/24

Abstract: In order to more effectively use read only memory space of a personal computer system, ROM code is selectively located or mapped to either an address boundary which is an even or odd integer multiple of one half the capacity of the read only memory device in which the ROM code is stored. The ROM code is stored in the read only memory device in two fields. In a first field, the ROM code is broken up into two segments, and the first segment precedes the second segment. In the second field, the same two segments are stored, but the second segment is stored preceding the first segment. A register, for storing page select bits, provides an input to an address decoder and an input to an adder, which adds unity to the contents of the register and provides its output to the address decoder as well. Accordingly, the address decoder will respond to either the page which is identified by the page select bits or the page following the identified page. The LSB of the page select bits is used in addressing the read only memory device to select between the first field (selected when the LSB is zero) or the second field (selected when the LSB is unity).

公开(公告)号：BR8906348A

公开(公告)日：1990-08-21

申请号：BR8906348

申请日：1989-12-08

Applicant: IBM

Inventor： BUSH GREGORY FREDERICK ,  KEENER DON STEVEN ,  MOREL JEANNE ELLEN ,  VOORHEES RICHARD W

IPC: G06F12/06 ,  G06F12/02

Abstract: In order to more effectively use read only memory space of a personal computer system, ROM code is selectively located or mapped to either an address boundary which is an even or odd integer multiple of one half the capacity of the read only memory device in which the ROM code is stored. The ROM code is stored in the read only memory device in two fields. In a first field, the ROM code is broken up into two segments, and the first segment precedes the second segment. In the second field, the same two segments are stored, but the second segment is stored preceding the first segment. A register, for storing page select bits, provides an input to an address decoder and an input to an adder, which adds unity to the contents of the register and provides its output to the address decoder as well. Accordingly, the address decoder will respond to either the page which is identified by the page select bits or the page following the identified page. The LSB of the page select bits is used in addressing the read only memory device to select between the first field (selected when the LSB is zero) or the second field (selected when the LSB is unity).

公开(公告)号：GB2225884A

公开(公告)日：1990-06-13

申请号：GB8927950

申请日：1989-12-11

Applicant: IBM

Inventor： BUSH GREGORY FREDERICK ,  KEENER DON STEVEN ,  MOREL JEANNE ELLEN ,  VOORHEES RICHARD W

IPC: G06F12/06

Abstract: In order to more effectively use read only memory space of a personal computer system, ROM code is selectively located or mapped to either an address boundary which is an even or odd integer multiple of one half the capacity of the read only memory device in which the ROM code is stored. The ROM code is stored in the read only memory device in two fields. In a first field, the ROM code is broken up into two segments, and the first segment precedes the second segment. In the second field, the same two segments are stored, but the second segment is stored preceding the first segment. A register, for storing page select bits, provides an input to an address decoder and an input to an adder, which adds unity to the contents of the register and provides its output to the address decoder as well. Accordingly, the address decoder will respond to either the page which is identified by the page select bits or the page following the identified page. The LSB of the page select bits is used in addressing the read only memory device to select between the first field (selected when the LSB is zero) or the second field (selected when the LSB is unity).