Browse Prior Art Database

Input/Output Address Space Sharing for Personal Computers

IP.com Disclosure Number: IPCOM000040475D
Original Publication Date: 1987-Nov-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 2 page(s) / 64K

Publishing Venue

IBM

Related People

Huynh, DH: AUTHOR [+3]

Abstract

A technique is described whereby input/output (I/O) attachment features, which are added to personal computers (PCs), are provided addressing compatibility by sharing I/O address circuit space with features permanently installed in the PC. In prior art, the addressing circuitry for I/O attachment features was typically installed on the individual circuit cards for that feature. The concept described herein allows these attachments to either replace or coexist with an on-board attachment that overlaps it in the I/O address space. The planar circuit board of the PC typically contains all of the circuitry required to allow the PC to function for its basic operation. However, additional circuitry is now incorporated to have the planar board increase its operational functions by incorporating I/O features within the planar board.

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Input/Output Address Space Sharing for Personal Computers

A technique is described whereby input/output (I/O) attachment features, which are added to personal computers (PCs), are provided addressing compatibility by sharing I/O address circuit space with features permanently installed in the PC.

In prior art, the addressing circuitry for I/O attachment features was typically installed on the individual circuit cards for that feature. The concept described herein allows these attachments to either replace or coexist with an on-board attachment that overlaps it in the I/O address space. The planar circuit board of the PC typically contains all of the circuitry required to allow the PC to function for its basic operation. However, additional circuitry is now incorporated to have the planar board increase its operational functions by incorporating I/O features within the planar board. This required the planar board to have addressing capability for those features. I/O support gate array 10, as shown in the figure, provides the controls for the selection of I/O devices, such as hard file, serial and parallel ports, planar video, diskettes, direct memory access (DMA), etc. An enable/disable bit command signal is used to activate the features, as required by the program. In the case of video attachment 11, the enable bit will also degate memory read/write signals 12 connected to I/O channel 13. If the attachment card, overlapping the I/O address space of the on-board a...