Intel MultiProcessor manual Conventions Used in This Document, For More Information

MultiProcessor Specification

1.6 Conventions Used in This Document

Signal names that are followed by the character # represent active low signals. For example, FERR# is active when at its low-voltage state.

Throughout this document, the Intel 82489DX APIC is referred to as the “discrete APIC.” The term “integrated APIC” is used to refer to an APIC integrated with other system components, such as the Pentium 735\90 and 815\100 processors. This specification uses the term APIC to refer to both discrete and integrated versions.

The processors of the Intel486 and Pentium processor family are “little endian” machines. This means that the low-order byte of a multibyte data item in memory is at the lowest address, while the high-order byte is at the highest address. Illustrations of data structures in memory show the lowest addresses at the bottom and the highest addresses at the top of the illustration, as shown in Figure 1-2. Bit positions are numbered from right to left.

31	24 23	16 15		8	7	0
		RESERVED
		RESERVED
	RESERVED			TWO-BYTE FIELD
	ONE-BYTE		THREE-BYTE FIELD
	FIELD

INCREASING ADDRESSES

0CH

08H

04H

00H

31 24 23 16 15 8 7 0

HIGH-ORDER BITS LOW-ORDER BITS

Figure 1-2. Memory Layout Conventions

In some memory layout descriptions, certain fields are marked RESERVED. Software should initialize these fields as binary zeros, but should otherwise treat them as having a future, though unknown effect. SOFTWARE SHOULD AVOID ANY DEPENDENCE ON THE VALUES

IN THE RESERVED FIELDS.

1.7 For More Information

For more information, refer to any of the following documents:

∙82489DX Advanced Programmable Interrupt Controller (data book), Intel order number 290446

∙Intel486 Microprocessor Programmer's Reference Manual, Intel order number 240486

∙Intel Processor Identification with the CPUID Instruction AP-485, Intel order number 241618

∙Pentium Processor User’s Manual , Intel order number 241428

1-4 Version 1.4