Table of Contents
Advertisement
3.2.2.1 Memory Changing/Expansion
The system memory can be changed and/or expanded by installing appropriate 168-pin DIMM
types. In expanding the standard memory using modules from third party suppliers the following
DIMM type is recommended: 66-MHz (or faster) unbuffered SDRAM supporting CAS
latency (CL) 2 or 3 with a data access time (clock-to-data out) of 9.0 ns or less @ CL=2 and
CL=3. The memory may also be expanded using EDO memory, although slightly lower
performance may be experienced. The EDO DIMMs must be of the following type: 50/60 ns
unbuffered EDO RAM.
The 440LX features programmable drive strength of the memory bus signals to compensate for
differences in DIMM module loading. The 440LX does, however, exhibit limitations on DIMM
slot configurations, depending on the installed DIMM's complement of SDRAM chips. DIMMs
using SDRAM chips with a bandwidth of x4 (four bits) are not supported. Some
combinations of DIMMs using x8 and x32 SDRAM chips are also not supported. An
unsupported configuration will cause the BIOS to generate an error message (#213), correctable
by moving the DIMMs to one of the supported configurations listed in the table below.
Configuration #
NOTES:
The BIOS supports the use of ECC memory, complete with error logging and alerting. To obtain
the full benefit of ECC memory the system must be loaded exclusively with ECC DIMMs (not
mixed) since the 440LX cannot enable ECC DIMMs individualy.
Access to the DIMM's EEPROM is through an I
AX-E827h (discussed in Chapter 8, "BIOS ROM"). The system can be configured using a
mixture of SDRAM, EDO RAM, and ECC RAM of different speeds, although doing so will
cause the BIOS to configure the system to the weakest (slowest) DIMM type installed. . If the
BIOS finds an installed module that is not supported then the memory controller is programmed
to indicate empty rows as appropriate.
All DIMMs, regardless of RAM type, must comply with JEDEC serial presence detect (SPD)
specification revision 1.0 or later. The RAM type (as well as other information) is detected
during power-up by the system BIOS using the SPD method, which reads the EEPROM on each
DIMM to obtain identification data such as the type and operating parameters. This system also
provides support for 256-byte EEPROMs to include additional Compaq-added features such as
the part number, serial number, and error logging. The SPD format as supported in this system is
shown in Table 3-5.
DIMM Slot J10 [1]
1
x8
2
x8
3
x32
4
x32
5
x32
6
None
7
x32
To determine SDRAM chip bandwidth, divide 64 by the number of RAM chips on
one side of the DIMM (valid divisor will be 2 or multiples of 4; round down for ECC DIMMs).
[1] Slot closest to edge of board.
[2] Slot closest to 440LX (located under SEC cartridge).
Compaq Deskpro 4000 and 6000 Personal Computers
First Edition - October 1997
Technical Reference Guide
DIMM Slot J11
DIMM Slot J12 [2]
x8
x32
x8
x32
x32
x32
None
2
C-type bus interface using BIOS call INT 15,
featuring the Pentium II Processor
x8
x8
x8
x8
x32
X8
X8
3-7
Advertisement
Table of Contents
