Intel 8008 (i8008) microprocessor family

The first 8-bit microprocessor, Intel 8008 (i8008) was released 5 months after Intel 4004. The 8008 was available in two speed grades - 500 KHz and 800 KHz. Because it took the CPU from 5 to 8 cycles to execute each instruction, the effective rate of instruction execution was:

  • From 45,000 to 100,000 instructions per second for Intel 8008
  • From 72,000 to 160,000 instruction per second for Intel 8088-1

These numbers assume that the CPU uses fast memory and doesn't require wait states to access the memory. Although the effective speed in instructions per second of the 8008 microprocessor sometimes is lower than the effective speed of the 4004 CPU, overall performance of the i8008 was greater due to faster effective speed of some instructions, 8-bit architecture and more efficient instruction set. The 8008 had other advantages over the 4004:

  • The processor supported of 16 KB of memory (ROM and RAM combined).
  • The size of internal CPU stack was 7 levels in contrast to 3 level-stack for the i4004.
  • The Intel 8008 could handle interrupts.

One of the drawbacks of the Intel 8008 was the absence of direct memory addressing. To access data in memory the memory address had to be stored in H and L registers, and only then the processor could indirectly access the memory. This limitation was removed in Intel 8080.

Intel 8008 microprocessor was used in Mark-8 computer, which is considered to be the first personal computer.

Die pictures: Intel C8008
Links
History
Architecture
Identification
Pinouts
Support chips
At a glance
Type:
8-bit microprocessor
Technology:
PMOS
Introduction:
1972
Frequency:
500 KHz - 800 KHz

DDR U808D

18-pin DIP
East German clone of Intel 8008 processor
DDR U808D

Intel C8008 (purple/gold/gold)

0.5 MHz
18-pin ceramic DIP
Gray ceramic/gold top/gold pins
Intel C8008 (purple/gold/gold)

Intel C8008 (no ground strap)

0.5 MHz
18-pin ceramic DIP
Purple ceramic/gold top/gold pins
No ground strap
Intel C8008 (no ground strap)

Intel C8008-1

0.8 MHz
18-pin ceramic DIP
Purple ceramic/gold top/gold pins
Intel C8008-1

Intel D8008

0.5 MHz
18-pin ceramic DIP
Intel D8008

Intel D8008-1

0.8 MHz
18-pin ceramic DIP
Intel D8008-1

Microsystems International MF8008R

0.5 MHz
18-pin ceramic DIP
Gray ceramic/gold top/gold pins
Microsystems International MF8008R

Microsystems International MF8008-1R

0.8 MHz
18-pin ceramic DIP
Microsystems International MF8008-1R

Siemens SAB8008-1C

0.8 MHz
18-pin ceramic DIP
Purple ceramic/gold top/gold pins
Siemens SAB8008-1C
(c) Copyright 2003 Gennadiy Shvets