6-6 Technical information
Microprocessor
The 80386SX is a high-performance microprocessor with a 16-bit
external data path, up to 16 megabytes of directly addressable physi-
cal memory and up to 64 terabytes of virtual memory space. The
operating speed of the 80386SX chip is 10MHz in Normal mode and
20MHz in Turbo mode.
The 80386SX operates in two modes: protected virtual address mode
and real address mode.
Protected Virtual Address Mode
In protected mode, software can perform a task switch to enter virtual
8086 mode tasks. Each task behaves with 8086 semantics, thus
allowing 8086 software (an application program or an entire operation
system) to execute. The virtual 8086 tasks can be isolated and
protected from one another and the host 386SX microprocessor opera-
tion system by use of paging.
Protected mode will use one of two different address spaces, depend-
ing on whether or not paging is enabled. Every selector has a logical
base address of up to 32 bits in length. This 32-bit logical base address
is added to the effective address to form a final 32-bit linear address.
If paging is disabled, this final linear address reflects physical memory
and is truncated so that only the lower 24 bits of this address are used
to address the 16 megabyte memory address space. if paging is
enabled this final linear address reflects a 32-bit address. This is
translated through the paging unit to form
a
16-megabyte physical
address.
Chapter 6: Appendix
17
Содержание Apex 386SX/20
Страница 1: ...PEER 2030 2 O M H z 3 8 6 S X S Y S T E M U ser s Manual ...
Страница 15: ...Chapter 1 System Overview ...
Страница 38: ...Chapter 2 Setting Up Your System ...
Страница 43: ...Figure 2 2 The Location of W9 80386SX and 80387SX Chapter 2 Setting Up Your System 5 ...
Страница 48: ...Figure 2 6 512KB Total Onboard System Memory 10 Chapter 2 Setting Up Your System ...
Страница 49: ...Figure 2 7 640 KB Total Onboard System Memory Chapter 2 Setting Up Your System 11 ...
Страница 50: ...Figure 2 8 1 MB Total Onboard System Memory 12 Chapter 2 Setting Up Your System ...
Страница 51: ...Figure 2 9 1 5 MB Total Onboard System Memory Chapter 2 Setting Up Your System 13 ...
Страница 52: ...Figure 2 11 2MB Total Onboard System Memory B 14 Chapter 2 Setting Up Your System ...
Страница 53: ...Figure 2 12 3MB Total Onboard System Memory Chapter 2 Setting Up Your System 15 ...
Страница 54: ...Figure 2 13 4MB Total Onboard System Memory 16 Chapter 2 Setting Up Your System ...
Страница 55: ...Figure 2 14 5MB Total Onboard System Memory Chapter 2 Setting Up Your System 17 ...
Страница 61: ...Chapter 3 Operating Your System ...
Страница 80: ...Chapter 4 Keyboard ...
Страница 90: ...Chapter 5 Troubleshooting ...
Страница 98: ...Appendix ...
Страница 102: ...Figure 6 3 Connecting a Floppy Disk Drive Figure 6 4 Connecting a Floppy Disk Drive to an FDC Card 4 Chapter 6 Appendix ...
Страница 103: ...Figure 6 5 Connecting a Hard Disk Drive Figure 6 6 Connecting a Hard Disk Drive to an HOC Card Chapter 6 Appendix 5 ...
Страница 123: ...Chapter 7 Glossary ...