Browse Prior Art Database

Memory Presence Circuit for a Processor Complex

IP.com Disclosure Number: IPCOM000106253D
Original Publication Date: 1993-Oct-01
Included in the Prior Art Database: 2005-Mar-20
Document File: 2 page(s) / 76K

Publishing Venue

IBM

Related People

Dang, TT: AUTHOR [+4]

Abstract

Disclosed is a circuit included in a processor complex card for use in detecting the presence of system memory residing on the processor complex card.

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

Memory Presence Circuit for a Processor Complex

      Disclosed is a circuit included in a processor complex card for
use in detecting the presence of system memory residing on the
processor complex card.

           A computer system, which includes a memory presence
detection circuit in a module on its system board, is upgraded with
the installation of a processor complex card having all of the CPU
local bus components, including system memory and a circuit 10, shown
in the Figure, for detecting the presence of such memory.

           Memory presence detection is done, during system setup,
when an I/O cycle writes data 07FH to address 094H.  When a cycle to
write to address 094H is decoded from address lines 12 by address
decoder circuit 14, an input signal to AND gate 16 is produced, so
that register 18 is set according to data lines 20 with a CMD signal
on line 22.  The output of register 18 provides an input to decoder
circuit 24, which in turn produces an output signal on line 26 when
the data stored in register 18 is 07FH, indicating that the system is
in setup.

           During system setup, this signal on line 26 produces a
G103 input to decoder circuit 14, so that when a cycle to write to
address 103H occurs, an output from decoder circuit 14 to AND circuit
28, with a CMD signal on line 22, provides a clock signal to register
30 so that the signals from three of the data lines 20 are latched
into register 30.  The outputs of register 3...