What is the difference between the Intel 8080 and the Intel 8085?

Answer 1

The 8086 has 16 bit data bus; the 8088 has an 8 bit data bus. The 8086 has a 6 byte instruction queue, and the 8088 has a 4 byte queue. The 8088 was the chip used in the first IBM PC; the 8086 wasn't used until later models. Since they share the exact same instruction set, which is referred to as the "x86 instruction set" these days, this is often confused. 8085 is a 8 bit processor,number of flags are 5 and memory capacity is 64KB while 8086 is a 16 bit processor ,number of flags are 9 and memory capacity is 1 MB.The main difference between 8085 and 8086 is that 8086 uses pipelining. The 8086/8088 microprocessor is a 16 bt computer, with a 20 bit address bus using a segmented memory architecture. The execution unit architecture, registers, instructions, etc. in both is the same. The bus interface unit on the 8086 is 16 bits wide, where on the 8088 it is 8 bits wide.

Answer 2

The 8086/8088 is a 16 bit processor running on a 16 bit (8086) or 8 bit (8088) bus with a 20 bit address. It can address 1 MB of memory. Addressing consists of adding the program's effective address to the (left shifted by 4) value of one of the segment registers. Think of segments as multiple 64kb regions of memory, overlapping at a distance of 16 bytes.

The 80286 is a 16 bit processor running on a 16 bit bus with a 24 bit address. It can address 16mb of memory.

In real mode, it operates the same as an 8086. This is the power on reset state. In protected mode, the segment register changes meaning. Instead of a segment address (left shifted by 4 base address), the segment register is an index into a page descriptor table, which is a table that supports virtual mode. Each element in the page descriptor table also contains information about the protection status of that page, so that page protection can be provided.

Unfortunately, since the meaning of the segment register changed, the 80286 was not object code compatible with programs written for the 8086/8088. This is one of the factors that made the 80286 unpopular.

Intel layed the groundwork for solution of the compatibility problem with the 80386, which provided a Virtual 8086 protected mode, in which each process "thought" it was running on an 8086. This was the architecture of Windows 3.x. Full utilization of the 32 bit architecture of the 80386 was realized when 32 bit operating systems such as Windows 95 and its successors came into being.

Answer 3

The only practical difference between an 8086 and an 8088 is that the address bus of the 8086 is 16 bits wide, and that of the 8088 is 8 bits wide. The instruction set and most of the internal construction is the same. The two run nearly identically, except that the 8088 is slower under some circumstances because of its narrower bus. In fact it is not obvious how a program can tell which it is running on (I used to know how to do this, twenty years ago, but I have forgotten).

Answer 4

The 8085 was the next version of the 8080. It ran on a single +5V power supply, hence the 5 in the part number. It also had a multiplexed address bus, freeing up 7 pins, 7 pins which became SID/SOD (Serial I/O), and RST5.5, RST6.5, RST7.5 and TRAP, which were single pin interrupts.

Answer 5

S.No.8086 Microprocessor8088 Microprocessor1The instruction Queue is 6 byte long.

The instruction Queue is 4 byte long.

2In 8086 memory divides into two banks, up to 1,048,576 bytes.

The memory in 8088 does not divide in to two banks as 8086.

3The data bus of 8086 is 16-bit wide

The data bus of 8088 is 8-bit wide.

4It has BHE( bar ) signal on pin no. 34 & there is no SSO(bar) signal.

It does not has BHE( bar ) signal on pin no. 34 & has only SSO(bar) signal. It has no S7 pin.

5The output signal is used to select memory or I/O at M/IO(bar) but if IO(bar)/M low or logic '0' it selects I/O devices and if IO(bar)/M is high or logic '1'it selects memory.The output signal is used to select memory or I/O at M(bar)/IO but if IO/M(bar) is low or at logic '0',it selects Memory devices and if IO/M(bar) is high or at logic '1'it selects I/O.6It needs one machine cycle to R/W signal if it is at even location otherwise it needs two.

It needs one machine cycle to R/W signal if it is at even location otherwise it needs two.

In 8086, all address & data Buses are multiplexed.

In 8088, address bus, AD7- AD0 buses are multiplexed.

It needs two IC 74343 for de-multiplexing AD0-AD19.

It needs one IC 74343 for de-multiplexing AD0-AD7.