Browse Prior Art Database

Microprocessor Dual Usage Socket

IP.com Disclosure Number: IPCOM000114240D
Original Publication Date: 1994-Nov-01
Included in the Prior Art Database: 2005-Mar-28
Document File: 4 page(s) / 97K

Publishing Venue

IBM

Related People

Price, WE: AUTHOR [+2]

Abstract

Described is a hardware implementation to enable a Personal Computer (PC) circuit board to accept two types of microprocessors in the same holding socket. The described implementation circuitry provides detection signals that automatically change pin-out connections to the types of microprocessors, enabling a single socket to be used.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Microprocessor Dual Usage Socket

      Described is a hardware implementation to enable a Personal
Computer (PC) circuit board to accept two types of microprocessors in
the same holding socket.  The described  implementation circuitry
provides detection signals that automatically change pin-out
connections to the types of microprocessors, enabling a single socket
to be used.

      The implementation involves the Intel 486DX2* microprocessor,
code name P24, and an upgrade microprocessor, code name P24T.  In
prior art, two sockets were required.  The upgrade involved the P24
such that when the P24T was plugged into the socket on the board it
would disable the 486DX2 and would have unimpeded the control of all
data, address, and control signals.  Unfortunately, the upgrade
socket used for the P24T microprocessor required a large amount of
board space and a signal to indicate that an upgrade microprocessor
had been installed so as to tri-state all outputs.  Fig. 1 shows a
block diagram of how the prior art upgrade connection was made
requireing two sockets on the circuit board:
        P24 / P24 SIGNAL DIFFERENCES
            P24             P24T
        Pin    Signal    Pin    Signal
        B10    NC        C11    SMI#
        A13    NC        B14    FERR#
        C12    NC        D13    SMIACT#
        B14    TMS       C15    UP#
        C14    FERR#     D15    TMS
        S4     BRDYC#    T5     NC

      The concept described herein implements circuitry whereby the
system can be made to detect which microprocessor is installed.  In
addition, the circuitry will automatically change the pin-out
connections without the need for mechanical jumpers, as was required
in prior art upgrades.  The result is that...