Configurations; System Upgrades; Expanded Memory - Philips PCL304 Service Manual

3.1 System Upgrades
Description
80C387SX numeric co-processor
2MB SIMM (80ns)
4MB SIMM (80ns)
3.2 Memory configurations
* Extended Memory:
This is a simple continuation of Base 1MB memory.
less using special programs or utilities, most of the soft-
ware applications will be unable to address this memory.
* Expanded Memory:
Extended memory can be transformed into Expanded
memory (LIM EMS 4.0).
This is a tecnique of forming a "window" in the Base me-
mory through which some programs can see "pages" of
data in Expanded memory. The program can therefore
address all RAM.
* Shadow RAM:
Shadow RAM applies only to the first 384K of extended
memory (standard notebooks). Instead of using this spa-
ce as extended or expanded memory, the system and/or
VGA BIOS can be copied to this space.
It will lead to some performance gain, especially in appli-
cations which make extensive calls on the BIOS.
Refer to the documentation of the software (program) to
be installed to decide which option to choose.
Summarizing:
3-1
Memory size 1M 1M 1M 3M MM 3M
EMS size 384K 256K Off 2304K 280K 256K
Shadow Ram Off 128K Off 128K 28K 128K
Extended Off Off 384K Off Mi 1M
Mem
Fig. 3-1
Memory size 5M 5M 5M 5M 5M
Fig. 3-2
3.2.1 Expanded Memory
The on-board chipset is fully hardware/softwal@ compatible
with the Lotus Intel Microsoft Expanded Memory Specifica-
tions (LIMEMS) version 4.0. This implementation allows a
64KB block in the area from 040000h - O9FFFFH (256KB -
640KB) or from 0C0000h to OEFFFFh to be used as a wind-
ow, allowing the complete 7552KB (maximum) Of on-board
RAM to be accessed. Accessing is accomplished by means
of paging. The 64KB block is divided into four! 6KB pages
which can access individual portions of the 7552KB area.
Memory address map
The System Memory Map is shown as follows:
lO9FFFF __|tes |
eee
128K By-| Video RAM (Graphic
|
|OBFFFF _ |tes Display Buffer,
a ea EMS default memory
ODFFFF Bytes base address
peso
eas | ROM for Video BIOS
OEFFFF Bytes
pee 64K ROM for System BIOS
| OFF FFF Bytes |
100000- | 15M Memory - 1M to 15M
Bytes installed on memory
| FDFFFF expansion options
[FEoo00- | 64K Duplicated code
Bytes assignment at address
FFFFFF OEO000
|FFOO0O- | 64K Duplicated code
Bytes
[FEFFFF
assignment at address
[FFFFFF | ___|__OF 0000
ET
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