Dell Latitude CP, Reference And Troubleshooting Manual

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Troubleshooting Your Computer 3-15
Memory Allocations
Table 3-5 provides a map of the conventional memory area.
When the microprocessor or a program addresses a location
within the conventional memory range, it is physically
addressing a location in main memory.
NOTE: To view memory allocations in Windows 95,
select the Start button, and point to Settings and then to
Control Panel. Double-click the System icon. Select the
Device Manager tab, and then double-click Computer.
Table 3-6 provides a map of the upper memory area.
Some of these addresses are dedicated to various system
devices, such as the system/video basic input/output sys-
tem (BIOS). Others are available for use by expansion
cards and/or an expanded memory manager (EMM).
When the microprocessor or a program addresses a loca-
tion within the upper memory area, it is physically
addressing a location within one of these devices.
I/O Memory Map
Table 3-7 provides a map of memory addresses reserved by
the system for peripheral I/O devices. Use the information in
Table 3-7 to determine if the memory address of an external
peripheral (such as a PC Card) conflicts with a memory
address reserved by the system.
Check the documentation of the external I/O device to deter-
mine its memory address. If there is a conflict with a memory
address reserved by the system, change the address of the
device.
NOTE: To view I/O addresses in Windows 95, select the
Start button, and point to Settings and then to Control
Panel. Double-click the System icon. Select the Device
Manager tab, and then double-click Computer.
IRQ14 Reserved; generated by the hard-disk
drive to indicate that the drive requires the
attention of the microprocessor
IRQ15 Reserved; generated by CD-ROM drive in
the modular bay to indicate that the drive
requires the attention of the microprocessor
Table 3-5. Conventional Memory Map
Address Range Use
00000h–003FFh Interrupt vector table
00400h–00FFFF BIOS data area
00500h–005FFh
MS-DOS
®
and BASIC work
area
00600h–9FBFFh User memory
NOTE: For the full name of an abbreviation or acronym
used in this table, see the Glossary in the online System
User’s Guide.
Table 3-4. IRQ Line Assignments (continued)
IRQ Line Reserved/Available
NOTE: For the full name of an abbreviation or acronym used in
this table, see the Glossary in the online System User’s Guide.
Table 3-6. Upper Memory Map
Address Range Use
0009FC00–0009FFFF PS/2-mouse data area
000A0000–000BFFFF Video RAM
000C0000–000CBFFF Video BIOS
000CC000–000CDFFF Reserved for PC Card
000F0000–000FFFFF System BIOS
00100000–03FFFFFF High memory area
FD000000–FDFFFFFF Video RAM
FF200000–FF2FFFFF Video RAM
FFFE0000–FFFFFFFF BIOS ROM
NOTE: For the full name of an abbreviation or acronym
used in this table, see the Glossary in the online System
User’s Guide.