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IBM Personal Computer Extended I/O Bus

IP.com Disclosure Number: IPCOM000060461D
Original Publication Date: 1986-Apr-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 2 page(s) / 13K

Publishing Venue

IBM

Related People

Alewine, NJ: AUTHOR [+3]

Abstract

A technique is described whereby two circuit cards are connected between the input/output (I/O) channel of the IBM Personal Computer (PC) and the industry standard Std Bus, so as to expand the I/O addressing capabilities of the IBM PC. The use of the IBM PC directly as a machine controller is limited by the number of expansion slots. The use of the industry standard Std Bus, although capable of handling I/O addressing, is limited since it does not have the flexibility of the IBM PC. The technique described herein combines the Std Bus I/O with the IBM PC processing capabilities to provide expansion of I/O addressing at full operating speed. Utilized are a PC Control (PCC) card and a Std Buffer (SB) card. A cable connects to the cards so that they may be located up to fifteen feet from each other.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 51% of the total text.

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IBM Personal Computer Extended I/O Bus

A technique is described whereby two circuit cards are connected between the input/output (I/O) channel of the IBM Personal Computer (PC) and the industry standard Std Bus, so as to expand the I/O addressing capabilities of the IBM PC. The use of the IBM PC directly as a machine controller is limited by the number of expansion slots. The use of the industry standard Std Bus, although capable of handling I/O addressing, is limited since it does not have the flexibility of the IBM PC. The technique described herein combines the Std Bus I/O with the IBM PC processing capabilities to provide expansion of I/O addressing at full operating speed. Utilized are a PC Control (PCC) card and a Std Buffer (SB) card. A cable connects to the cards so that they may be located up to fifteen feet from each other. Buffers are used in each card for the operation of the address bus, data bus and control lines. To facilitate and establish Std Bus locations in the memory address maps of the PC, DIP (Dual Inline Package) switches are located on the PCC card to place the Std Bus memory in any one of sixteen memory pages. One switch is designated "I/O Map" to determine if the Std Bus I/O will operate as memory or as I/O to the IBM PC. If this switch is on, the PC I/O operations will not be passed on to the Std Bus and the Std Bus I/O will operate as a page of the PC memory, as selected by four PC I/O switches. In actual operation, the IBM PC will read or write to this page in memory so as to pass the I/O information on to the Std Bus. If the I/O Map switch is off, all PC I/O write addressing is passed on to the Std Bus and PC I/O reads from selected addresses will gate data back onto the PC data bus. The PC memory read and write as well as the I/O read and write control lines are translated into read and write control lines which are then passed directly to the Std Bus. These control lines are passed on only if the corresponding addresses fall within ranges established by the DIP switches in the control card. A wait state is auto...