Dell WorkStation 210 manual 0HPRU\$OORFDWLRQV

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A microprocessor 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. 7DEOHAll system%￿￿￿memory&RQYHQWLRQDO0HPRU\above this 1 MB is called0DSextended memory and cannot be directly addressed$GGUHVV5DQJHby MS-DOS–based8VHprograms without the aid of some special memory- managing software.

Table B-9 provides a map of the conventional memory area. When the microprocessor or a program addresses a location within the conventional memory range, it is physi- cally addressing a location in main memory, which is the only main memory it can address under MS-DOS.

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
90000h–9FBFFh	User memory

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

Table B-10 provides a map of the upper memory area. Some of these addresses are dedicated to various system devices, such as the system BIOS. Others are available for use by expansion cards and/or an expanded memory manager (EMM). When the microprocessor or a program addresses a location within the upper memory area, it is physically addressing a location within one of these devices.

B-16 Dell Precision 210 Desktop Systems User’s Guide