Intel 80286 Processor

关于 Intel 80286

80286（简称 286）就是造成个人电脑风行的一款中央处理器，在发布后的六年中，全球 286 的个人电脑一共出货了一千五百万台。它除了改善了一些指令的执行速度，同时也增加最大内存支持到 16 MB。当初预计这种内存支持大概在十年之内都不会需要再增加了。

80286 芯片含有十三万四千个晶体管、16 Bit 数据总线，工作频率由最初的 4 MHz 逐步提高到 25 MHz。其内部和外部数据总线皆为 16 Bit，内存寻址总线为 24 Bit。与 8086 相比，80286 内存寻址功能达到了 16 MB，并可以使用虚拟内存模拟大量内存空间，因而大大扩展了 80286 的工作范围，还能通过多工处理器在各线程间来回快速切换，以同时运算多个线程，其速度比 8086 提高了 5 倍甚至更多。IBM 公司将 80286 用在技术更为先进 AT 机中，与 IBM PC XT 机相比，AT 机内存一般可扩展到 16 MB，可支持更大的硬盘，支持 VGA 显示系统，比 PC XT 机在性能上有了重大的进步。

关键数据：

• 134,000 个晶体管
• 1.5 µm HMOS 制造技术
• 16 位内部数据总线
• 16 位外部数据总线
• 24 位地址总线
• 支持高达 16 MB 的内存和高达 1 GB 的虚拟内存
• 掌握真实和保护模式

Introduction

The 80286 was introduced by Intel on February 1, 1982. As the 80186/80188 CPUs were not really significant to personal computing, the 80286 was Intel’s next step processor for micro computers.

Intel added four more address lines to the 8086/80186 design. The 8086, 8088, 80186, and 80188 all contained 20 address lines, giving these processors one megabyte of addressibility (2^20 = 1MB). The 80286, with its 24 address lines, gives 16 megabytes of addressibility (2^24 = 16 MB).

The most substantial difference between the 80286 and the 8086/8088 is the addition of a protected mode. In protected mode, segment registers became pointers into a table of memory descriptors rather than being a direct part of the address. Among other things, protected mode allows safe execution of multiple programs at once by protecting each program in memory. DOS normally operates in real mode, in which segment registers act just as they do in the 8086/8088. Protected mode is used by Microsoft Windows, IBM’s OS/2 and UNIX. (For an introduction to protected mode please refer to this source)

The 80286 is a much more powerful CPU than the 8086, offering 3-6 times the performance of it. The 6 MHz 80286 is the CPU of the IBM AT (Advanced Technology), which also introduced a 16-bit motherboard and 16-bit expansion bus to the PC world. The IBM AT was introduced in 1985 - three years after introduction of the 80286.

With the 80286, the first “chipsets” were introduced. The computer chipset is a set of chips that replaced dozens of other peripheral chips while maintaining identical functionality. Chips and Technologies became one of the first popular chipset companies.

The 80286 was typically made in 3 package versions, each with 68 contacts: a PGA-, CLCC- and a PLCC-package.

我的收藏

Intel R80286-10

Intel A80C286-12