Intel 8080
Summary
With the 8080, Intel launched its second 8-bit microprocessor in April 1974. It integrates about 6000 transistors. The direct successor of the 8008 has the same command set as well as the same register model so that existing assembler programs only need to be translated. The address bus grows to 16 bits. So the processor can address 64 KiB memory — four times more than its predecessor. Its clock frequency is 2 MHz.
Although the 8080 requires a separate clock generator (8224) and a bus controller (8228), it becomes a widely used microprocessor. Thanks to its 40 pin-DIP socket, it is easier to connect than the 8008 and thus forms the basis for the first home computers: the Altair 8800 from MITS, SOL-20 from Processor Technology and IMS Associates IMSAI 8080.
Intel can recover the high development costs after 5 months. In 1979, different chip producers sell about 500,000 units per month at a price of 3 to 4 USD.
Successor
The 8085 followed in March 1976, running at up to 5 MHz. The “5” refers to its single +5-volt supply, replacing the +5 V, −5 V and +12 V required by the 8080. In the same year, Intel began planning the 8086, released on 8 June 1978 and capable of running at up to 10 MHz.
The 8080 was so successful that the 8086 had to be compatible at assembly-language level. Modern x86 processors therefore trace their origins to the 8080. IBM chose the inexpensive 8088, introduced in June 1979, for its new PC range, released in 1981.
Sources and further links
Connections in the collection
In the exhibition concept
- Generations of computers · Area A, Section 1