1. 80286 Processor
2. 80486 Microprocessor Features

Reference – Microprocessor and Interfacing Notes – MI notes pdf – MI pdf notes – MI Pdf – MI Notes. Micro Processors & Interfacing – Douglas U. The 8088 and 8086 Micro Processors – PHI, 4th Edition, 2003. Micro Computer System 8086/8088 Family Architecture, Programming and Design – By Liu and GA Gibson, PHI. From the bitsavers.org collection, a scanned-in computer-related document.intel:: 80486:: Intel486 DX2 Microprocessor Data Book Jul92.

80286 Microprocessor is a 16-bit microprocessor that has the ability to execute 16-bit instruction at a time. It has non-multiplexed data and address bus. The size of data bus is 16-bit whereas the size of address bus is 24-bit.

It was invented in February 1982 by Intel. 80286 microprocessor was basically an advancement of 8086 microprocessor. Further in 1985, Intel produced upgraded version of 80286 which was a 32-bit microprocessor.

Now the question arises what are the factors that make 80286 more advantageous than 8086 microprocessor?

• It has non-multiplexed address and data bus that reduces operational speed.
• The addressable memory in case of 80286 is 16 MB.
• It offers an additional adder for address calculation.
• 80286 has faster multipliers that lead to quick operation.
• The performance per clock cycle of 80286 is almost twice when compared with 8086 or 8088.

Operating modes of 80286 microprocessor

80286 operates in two modes:

In real address mode, this microprocessor acts as a version of 8086 which is quite faster. Also without any special modification, the instruction programmed for 8086 can be executed in 80286. It offers memory addressability of 1 MB of physical memory.

The protected virtual-address mode of 80286 supports multitasking because multiple programs can be executed using virtual memory. This mode of 80286 offers memory addressability of 16 MB of physical memory along with 1 GB of virtual memory.

As using virtual memory, space for other programs can be saved. Sometimes bulky programs also do exist that cannot be stored in physical memory, so virtual memory is utilized in order to execute large programs.

This mode is used in 80286, so that in case of memory failure in real address mode, it can stay in protected manner.

What is virtual memory?

Virtual memory is that part of hard disk which can be utilized for storing large instructions inside the system. This extra memory can be addressed by the computer other than the physical memory.

When there exists an instruction that is to be loaded in the memory but whose size is greater than the provided physical memory. Then some part of hard disk is used in order to store that instruction, which is known as virtual memory.

Architecture of 80286 Microprocessor

The figure below shows the architectural representation of 80286 microprocessor:

As we have already mentioned earlier that it is a 16-bit microprocessor thus holds a 16-bit data bus and 24-bit address bus. Also, unlike the 8086 microprocessor, it offers non-multiplexed address and data bus, which increases the operating speed of the system.

80286 is composed of nearly around 125K transistors and the pin configuration has a total of 68 pins.

The CPU, central processing unit of 80286 microprocessor, consists of 4 functional block:

• Address Unit
• Bus Unit
• Instruction Unit
• Execution Unit

Firstly, the physical address from where the data or instruction is to be fetched is calculated, by the address unit. Once the physical address is calculated then the calculated address is handed over to the bus unit. More specifically we can say, that the calculated address is loaded on the address bus of the bus unit.

This address specifies the memory location from where the data or instruction is to be fetched. The fetching of data through the memory is done through the data bus. For faster execution of instruction, the BU fetches the instructions in advanced from the memory and stores them in the queue.

This is done through the bus control module. As we have discussed that the prefetched instructions are stored in a 6-byte instruction queue. This instruction queue then further sends the instruction to the instruction unit.

The instruction unit on receiving the instructions now starts decoding the instruction. As instructions are stored in prefetched queue thus the decoder continuously decodes the fetched instructions and stores them into decoded instruction queue.

Now after the instructions gets decoded then further these are needed to be executed. So, the instructions from decoded instruction queue are fed to the execution unit. The main component of EU is ALU i.e., arithmetic and logic unit that performs the arithmetic and logic operations over the operand according to the decoded instruction.

Once the execution of the instruction is performed then the result of the operation i.e., the desired data is send to the register bank through the data bus.

As we have already discussed that 80286 is just a modified version of 8086. The register set in 80286 is same as that of 8086 microprocessor.

• It holds 8 general purpose registers of 16 bit each.
• It contains 4 segment register each of 16-bit.
• Also has status and control register and instruction pointer.

Interrupt of 80286 Microprocessor

We know that whenever an interrupt gets generated in a system, then the execution of the current program is stopped and the execution gets transferred to the new program location where the interrupt is generated.

But once the interrupt gets executed then then in order to get back to the original program, its address as well as machine state must be stored in the stack. Basically there exist 3 categories of interrupt in 80286 microprocessor:

• External interrupt (Hardware interrupt)
• INT instruction interrupt (Software interrupt)
• Internally generated interrupt due to some exceptions

External or hardware initiate interrupt are those interrupts that gets generated due to an external input. And are basically of two types:

80286 Processor

1. Maskable interrupt
2. Non-maskable interrupt

Sometimes when multiple programs are allowed to be executed in a system, then this leads to generation of INT instruction, and such an interrupt is known as software interrupt.

Another interrupt in 80286 exist due to some unusual conditions or situations generated in the system that leads to prevention of further execution of the current instruction.

So, this is all about the modes of operation, architecture and interrupts of 80286 microprocessor.

Datasheet[edit]. DX2 Microprocessor Data Book (February ) · Intel DX2 Microprocessor Data Book (July ) · DX. The exposed die of an Intel DX2 microprocessor The Intel (“four- eighty-six”), also known as the i or is a higher .. Intel datasheets. The Intel , also known as the i or , is a higher performance follow- up to the Intel .. Intel datasheets · Low power SX and DX with variable freq.

The Intel ” four-eighty-six “also known as the i or is a higher performance follow-up to the Intel microprocessor. The was introduced in and was the first tightly [lower-alpha 1] pipelined x86 design as well as the first x86 chip to use more than a million transistors, due to a large on-chip cache and an integrated floating-point unit. It represents a fourth generation of binary compatible CPUs since the original of The i does not have the usual prefix because of a court ruling that prohibits trademarking numbers such as Later, with the introduction of the Pentium brandIntel began branding its chips with words rather than numbers.

The was announced at Spring Comdex in April At the announcement, Intel stated that samples would be available in the third quarter of and production quantities would ship in the fourth quarter of The instruction set of the i is very similar to its predecessor, the Intelwith the addition of only a few extra instructions, such as CMPXCHG which implements a compare-and-swap atomic operation and XADD, a fetch-and-add atomic operation returning the original value unlike a standard ADD which returns flags only.

Datasheet pdf – Microprocessor – Advanced Micro Devices

From a performance point of view, the architecture of the i is a vast improvement over the It has an on-chip unified instruction and data cachean on-chip floating-point unit FPU and an enhanced bus interface unit. Due to the tight pipelining, sequences of simple instructions such as ALU reg,reg and ALU reg,im could sustain a single clock cycle throughput one instruction completed every clock.

These improvements yielded a rough doubling in integer ALU performance over the at the same clock rate. Just as in thea simple flat 4 GB memory model could be implemented by setting all “segment selector” registers to a neutral value in protected modeor setting the same “segment registers” to zero in real modeand using only the bit “offset registers” xterminology for general CPU registers used as address registers as a linear bit virtual address bypassing the segmentation logic.

Virtual addresses were then normally mapped onto physical addresses by the paging system except when it was disabled. Real mode had no virtual addresses. Just as with thecircumventing memory segmentation could substantially improve performance in some operating systems and applications. The address bus used bits A However, problems continued when the DX was installed in local bus systems due to the high bus speed, making it rather unpopular with mainstream consumers as local bus video was considered a requirement at the time, though it remained popular with users of EISA systems.

More powerful iterations such as the OverDrive and DX4 were less popular the latter available as an OEM part onlyas they came out after Intel had released the next generation P5 Pentium processor family. Some were clones identical at the microarchitectural levelothers were clean room implementations 84086 the Intel instruction-set. IBM’s multiple source requirement is one of the reasons behind its xmanufacturing since the Intel and IBM have broad 80468 of these patents, and AMD was granted rights to the relevant patents in the settlement of a lawsuit between the companies.

Cyrix made a variety of compatible processors, positioned at the cost-sensitive desktop and low-power laptop markets. Unlike AMD’s clones, the Cyrix processors were the result of clean-room reverse-engineering. Cyrix also made “real” processors, which plugged into the i’s socket and offered 2 or 8 KB of cache.

The Motorola best known for its use in the Macintosh Quadra series and Amigawhile not compatible with thewas often positioned as the ‘s equivalent in features and performance.

Clock-for-clock basis the Motorola could significantly outperform the Intel chip. The Motorola performance lagged behind the later production systems.

Especially older peripheral cards normally worked well at such datasjeet as they often used standard MSI chips dataxheet of slower at the time custom VLSI designs. Ratasheet could give significant performance gains such as for old video cards moved from a or computer, for example. EISA offered a number of attractive features such as increased bandwidth, extended addressing, IRQ sharing, and card configuration through software rather than through jumpers, DIP switches, etc.

However, EISA cards were expensive and therefore mostly employed in servers and workstations. The VL-Bus operated at the same clock speed as the ibus basically being a local bus while the PCI bus also usually depended on the i clock but sometimes had a divider setting available via the BIOS. Even overseas in the United States it was popularised as “The World’s First ” in the September issue of Byte magazine shown right.

Later boards also supported Plug-And-Playa specification designed by Microsoft that began as a part of Windows 95 to make datasehet installation easier for consumers.

The introduction of 3D computer datashedt spelled the end of the ‘s reign, because 3D graphics make heavy use of floating point calculations and require a faster CPU cache and datashedt memory bandwidth. Developers began to target the P5 Pentium processor family almost exclusively with x86 assembly language optimizations e. Many dagasheet these games required the speed of the P5 Pentium processor family’s double-pipelined architecture.

In the general purpose desktop computer role, based machines remained in use into the earlys, especially as Windows 95, Windows 98, and Windows NT 4. Still, a number of machines have remained in use today, mostly for backward compatibility with older programs most notably gamesespecially since many of them have problems running on newer operating systems. However, DOSBox is also available for current operating systems and provides emulation of the instruction set, as well as full compatibility with most DOS-based programs.

Although the was eventually overtaken by the Pentium for personal computer applications, Intel had continued production for use in embedded systems.

(PDF) Datasheet PDF Download – Microprocessor Low Power Version

In May Intel announced that production of the would stop at the end of September This article is based on material taken from the Free On-line Dictionary of Computing prior to 1 November and incorporated under the “relicensing” terms of the GFDLversion 1.

Intel Intel In contrast loosely pipelined implies that some kind of buffering is used to decouple the units and allow them to work more independently. Both the original and the xchips of today are “loosely pipelined” in this sense, while the and the original Pentium worked in a “tightly pipelined” manner for typical instructions.

Also, leaving off the bit extension to intdl ISA connector allowed use of some early 8-bit ISA cards that otherwise could not be used due to the PCB “skirt” hanging down into that bit extension space.

The New York Times. Retrieved May 5, Retrieved 20 May The Intel vs.

Archived from the original on The exposed die of an Intel DX2 microprocessor. D estination I ndex. S tack P ointer.

intel :: 80486 :: i486 Microprocessor Data Sheet Apr89

I nstruction P ointer. S tack S egment. Floating-point registers 80 bits. Early variants were parts with disabled defective FPUs. The internal processor clock runs at twice the clock rate of the external bus clock. Designed to run at triple clock rate not quadruple as often believed; the DX3, which was meant to run at 2.

This CPU is dataheet embedded battery-operated and hand-held applications.

80486 Microprocessor Features