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8 Bit/16 Bit Memory Adapter

IP.com Disclosure Number: IPCOM000040950D
Original Publication Date: 1987-Apr-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Bischoff, G: AUTHOR [+3]

Abstract

A memory adapter capable of operating in either an 8 bit or 16 bit computer is described. The adapter automatically adjusts to an 8 bit or 16 bit data bus eliminating the need for selectable switches or programmable registers.

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This is the abbreviated version, containing approximately 84% of the total text.

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8 Bit/16 Bit Memory Adapter

A memory adapter capable of operating in either an 8 bit or 16 bit computer is described. The adapter automatically adjusts to an 8 bit or 16 bit data bus eliminating the need for selectable switches or programmable registers.

Typically an 8 bit computer uses a single row of I/O connectors, and a 16 bit computer uses a double row to allow I/O adapters to interface to the system. The memory adapter includes additional logic on the adapter card to sense when the card is plugged into a double row of connectors.

A block diagram of the adapter logic is shown in Fig. 1. In an 8 bit computer, even memory byte 1 contains all bytes with even addresses, and odd memory byte 3 contains all bytes with odd addresses. The control signals line provides an input to control logic 2 indicating whether the card is plugged into a single or double row of connectors. The signal may be the presence or absence of a ground condition. In the 8 bit computer, control logic 2 operates transceivers 4 and 5 to pass the data from both memory bytes 1 and 3 onto bus 7 to the single row of connectors.

In a 16 bit computer, memory byte 1 will contain the 8 least significant bits of each 16 bit data word and memory byte 2 will contain the 8 most significant bits. Control logic 2 receives a signal indicating the presence of a 16 bit system and operates transceivers 4 and 6 to pass the data onto both bus 7 and bus 8 to the double row of connectors.

The memory adapter describ...