The Intel 8088 microprocessor was a variant of the Intel 8086 and was introduced on July 1, 1979. It had an 8-bit external data bus instead of the 16-bit bus of the 8086. The 16-bit registers and the one megabyte address range were unchanged, however. The original IBM PC was based on the 8088.
8 bits
The address bus in the 8085 is 16 bits wide.
The 8086/8088 has an internal 20-bit address bus and 16-bit data bus. Externally, the address bus is 20-bits, and the data bus is 16-bits for the 8086 and 8-bits for the 8088.The data bus in the 8086 is 16 bits in size, while the address bus is 20.
It is my understanding that the 80286 has a 16-bit data bus. This was a doubling of the original 8086/8088 processors.
The 8088 brings in data in 8 bit chunks form the memory and must bring in two because internally it is 16 bit. The 8086 brings in the full 16 bits at one time. so it is the path to memory that differs.
You cannot address 1GB memory with the 8085 or the 8086/8088 without some kind of external demultiplexor that is software controlled. The address bus on the 8085 is 16 bits, giving addressibility of 64KB; while the address bus on the 8086/8088 is 20 bits, giving addressibility of 1MB. To address 1GB, you need a 30 bit address bus.
8088 processor accessed 1MB
The original 8088 processor had a maximum clock frequency of 5 MHz. As implemented in the original IBM PC, it ran at 4.77 MHz. There were variations of the 8088 that could run at 8 MHz.
The Intel 8088 is generally considered to be a 16-bit processor (most registers were 16 bit registers), and therefore had a 16-bit word length, although its external data bus was only 8 bits wide.
The 8088 is slower than the 8086 because the 8088 is running an 8-bit bus, while the 8086 runs a 16-bit bus. The two processors are the same, 16-bit processors, but the 8088 requires twice as many memory accesses to do the same amount of work as the 8086.
The number of data lines required in a 16-bit microprocessor is 16, in the internal view, but could be something else, such as 8, in the external view. In the 8086/8088, the processor is 16 bits, and its internal data bus is 16 bits. The 8086 provides 16 bits on the external bus, but the 8088 provides 8 bits, even though they are the same internal processor - the 8088 simply uses two memory cycles to move one word. The largest number that can be represented on a 16 bit bus depends on the interpretation of that number. An unsigned 16 bit number ranges from 0 to 65535, so 65535 is the largest value when unsigned. A 16 bit two's complement signed number ranges from -32768 to +32767, so +32767 is the largest value when signed.
The Intel 8088.