[ih] Intel 4004 vs the IMP

[Tony Li]

> But, processors such as the 68000s provided an excellent platform for
> companies that weren't burdened by millions of lines of assembly
> language software.  Most notably Cisco.  And, we all know how that
> story turned out.


If you’re implying that the 68000 somehow led to Cisco’s success, you’d be ignoring
the real workhorse, the TI DSP chip that was at the heart of Cisco’s performance.

This was the slave co-processor on the original MCI card and took care of moving
the bytes, managing the queues, doing the IP checksum and fixup, and doing the 
MAC rewrite. The 68k CPU was only responsible for doing the IP address lookup.
This is what allowed Cisco to get to 10Mbps Ethernet wire speed performance.

This was extended into the AGS+ cBus architecture, where again the DSP did
the lion’s share of the work and even took over doing the address lookup. 

Even the DSP was insufficient, so it was assisted by additional FPGA based
processing and then (after a major wrong turn) things transitioned to an ASIC
based forwarding architecture.

Microprocessors for all of their benefits have never been sufficient. More silicon has
always been a fundamental requirement.

T