The 4004 is not an ancestor of x86 even though the part numbers make it seem so. The 4004 was s 4-bit processor designed for calculators, and is different from x86 in almost every way. The 4004 isn't even a von Neumann architecture; it has separate data and instruction memory. The 4004 has weird instructions like KBP (Keyboard Process) to decode a calculator keyboard. I/O is done through RAM ports , not memory-mapped I/O, but I/O ports built into the RAM chips!
The origin of x86 is the Datapoint 2200, a desktop computer built from TTL chips. Datapoint contracted Intel to build a single-chip version of the 2200's processor, and Intel built the 8008, which was essentially a clone. Datapoint decided not to use the chip and gave the rights to Intel and the rest is history. Intel improved the 8008 to get the popular 8080 microprocessor. Intel then created the 8086, which was a 16-bit processor loosely based on the 8080. From that, the x86 architecture developed. Many features of x86 can be mapped back to the Datapoint 2200, such as little-endian.
Noncoml, did you really read the manual? The 4004 is unrelated to the x86-64.
Perhaps you are confusing it with the 8008 which is related to the 8080 which is related to the 8086 which is related to the 80286, 80386, 80486, and so forth.
Hmm, I don't know. Especially the way the segregate RAM into banks reminds me a lot of the x86 segments with their direct and indirect addressing modes.
Also a lot of instructions have similar names: CLC
You are right, it is not a true ancestor, but ready through the manual, it did seem to me that it was designed by the same people.
To be honest I haven't dig into other CPU families, so maybe these were pretty common.
The CLC - clear carry - instruction predates the 4004. The PDP-11 for instance used it. I think you're seeing patterns that aren't really there.
One thing the 4004 and 8008 do have in common is a similar floor plan for the chips. They both have the ALU on the left, data bus along the top, instruction decoding in the middle, registers on the right, and on-chip stack on the right. Other processors of that era (e.g. 6800, 6502, 8080) have very different layouts so it's not just coincidence. Texas Instruments produced the TMC 1795, a chip equivalent to the 8008 (before the 8008), and it also has a completely different layout.
If you look lower-level, at e.g. the ALU implementation or the register implementation or the pin drivers, there's less similarity. I would have expected they would essentially cut-and-paste some of these low-level pieces, but they are more different than I would expect.
The 4004 is so weird that it stands in a class of its own, for me. I'm not sure how much of its instruction set came from Busicom, the company that the 4004 was made for, instead of from Intel engineers.
It is a bit excessive to say that it is unrelated. Many of the techniques and methologies created for the 4004 were instrumental in the development the 8008. Also, the 4004, 8008, and 8080 were all designed by more or less the same people (esp. Faggin).
The 4004 has all kinds of strange instructions, like DAA (for BCD) and separate instructions for accessing main memory, ROM, and RAM. It's pretty clear that it was made to be in a calculator.
On the other hand, the 8008 has the familiar IN, OUT, MOV, PUSH, etc.
