IRQ6

Diskette drive interface

 

 

 

 

IRQ7

Parallel port

 

 

 

 

IRQ8

RTC

 

 

 

 

IRQ9

Available if ACPI is set to Off in System Setup program

 

 

 

 

IRQ10

Available

 

 

 

 

IRQ11

Available

 

 

 

 

IRQ12

Mouse controller

 

 

 

 

IRQ13

Math coprocessor

 

 

 

 

IRQ14

Primary EIDE interface (if Enabled in System Setup program)

 

 

 

 

IRQ15

Secondary EIDE interface (if Enabled in System Setup program)

 

 

NOTE: For the full name of an abbreviation or acronym used in this table, see the "Glossary".

Memory Allocations

A processor and programs operating under MS-DOS (real-mode operation) can address only 1 megabyte (MB) (1024 kilobytes [KB]) of system memory. This area is divided into conventional memory (sometimes called base memory) and upper memory. All system memory above this 1 MB is called extended memory and cannot be directly addressed by MS-DOS-based programs without the aid of some special memory-managing software.

Table B-10 provides a map of the conventional memory area. When the processor or a program addresses a location within the conventional memory range, it is physically addressing a location in main memory, which is the only main memory it can address under MS-DOS.

Table B-10. Conventional Memory Map

 

 

Address RangeUse

 

 

 

 

00000h-003FFh

Interrupt vector table

 

 

 

 

00400h-004FFh

BIOS data area

 

 

 

 

00500h-005FFh

MS-DOS and BASIC work area

 

 

 

 

00600h-0FFFFh

User memory

 

 

 

 

10000h-1FFFFh

User memory

 

 

 

 

20000h-2FFFFh

User memory

 

 

 

 

30000h-3FFFFh

User memory

 

 

 

 

40000h-4FFFFh

User memory

 

 

 

 

50000h-5FFFFh

User memory

 

 

 

 

60000h-6FFFFh

User memory

 

 

 

 

70000h-7FFFFh

User memory

 

 

 

 

80000h-8FFFFh

User memory