Browse Prior Art Database

Bus Extender for the STD Bus

IP.com Disclosure Number: IPCOM000061301D
Original Publication Date: 1986-Jul-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 2 page(s) / 49K

Publishing Venue

IBM

Related People

Bancroft, CE: AUTHOR [+3]

Abstract

This article describes a circuit arrangement which increases the number of printed circuit (PC) cards for attachment to the STD bus. This is accomplished by means of a logic card that plugs into a STD bus card rack and contains buffers for the bus signals and logic to control the buffers. A cable connects this card with a paddle card that plugs into a second STD bus card rack. This allows extending the STD bus to more than one card rack by providing the electrical drive capability required. As an option, the paddle card in the second bus card rack could contain buffers and thus allow the second bus card rack to be located remote from the first. The STD bus is used extensively for process control applications, but there is a limit to the number of memory, I/O, and special function cards that may be placed on the bus.

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Bus Extender for the STD Bus

This article describes a circuit arrangement which increases the number of printed circuit (PC) cards for attachment to the STD bus. This is accomplished by means of a logic card that plugs into a STD bus card rack and contains buffers for the bus signals and logic to control the buffers. A cable connects this card with a paddle card that plugs into a second STD bus card rack. This allows extending the STD bus to more than one card rack by providing the electrical drive capability required. As an option, the paddle card in the second bus card rack could contain buffers and thus allow the second bus card rack to be located remote from the first. The STD bus is used extensively for process control applications, but there is a limit to the number of memory, I/O, and special function cards that may be placed on the bus. Motherboards for the STD bus physically allow for up to 24 cards. Connecting two motherboards together directly would provide more card slots, but the cards would not have the capability to drive the extended bus. The circuit arrangement disclosed herein allows one primary STD bus rack to drive up to 16 secondary bus racks. All 16 address lines are buffered and passed on to a secondary STD bus. The data bus and read and write control lines are buffered and passed on, but the I/O and memory request control lines are not passed on and the data bus is not passed back unless the secondary STD bus has been selected by the logic on the card or the primary STD bus. The circuit arrangement of this disclosure is illustrated in the drawing. The logic devi...