The first 8-bit microprocessor, Intel 8008 was released 5 months after Intel 4004 microprocessor. The 8008 was available in two speed grades - 500 KHz and 800 KHz, but even the faster version 8008-1 was running a bit slower (in instructions per second) than the 4004. Nevertheless, overall performance of the 8008 was greater due to 8-bit architecture. The 8008 had other advantages over the 4004:
Support of 16 KB of memory (ROM and RAM combined).
Deeper stack: 7 levels instead of 3 levels.
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.