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The instruction set of the 8008 and subsequent Intel CISC CPUs were heavily based on CTC's design.
The chip (limited by its 18 pin DIP packaging) had a single 8-bit bus and required a very large amount of external logic to support it. For example, the 14-bit address, which could access 16K bytes of memory, needed to be latched by some of this logic in an external Memory Address Register (MAR). It could access 8 input ports and 24 output ports.
While a little slower in terms of instructions per second than the 4-bit Intel 4004 and Intel 4040, the fact that the 8008 processed data eight bits at a time and could access significantly more RAM actually gave it 3 to 4 times the true processing power of the 4-bit chips.
For controller and CRT terminal use this was an acceptable design, but it was too difficult to use for most other tasks. A few early computer designs were based on it, but most would use the later and greatly improved Intel 8080 instead.
| List of Intel microprocessors |
|
4004 |
4040 |
8008 |
8080 |
8085 |
8086 |
8088 |
iAPX 432 | 80186 | 80188 | 80286 | 80386 | 80486 | Pentium | Pentium Pro | Pentium II | Celeron | Pentium III | Pentium 4 | Pentium M | Itanium | Itanium 2(note: italics indicates non-main branch µPs) |