13 Oct
2007
13 Oct
'07
12:55 p.m.
"Roy J. Tellason" wrote:
Having heard of the 4004 of course, I know basically nothing about it.
Except that it's the part that was supposed to have started all this... And
the 4040? I've only seen mention of it now and then.
(Snip)
A poor scan of some datasheets are (were?) at
http://smithsonianchips.si.edu/ice/4004thb.htm
I know there are some others scans out there as well
although I have yet to run across a good set.
In brief, initially the main chips of the family were:
4001: 256*8 ROM & 4-bit IO
4002: 320-bit RAM & 4-bit IO
4004: 4-bit CPU
In a system a 4-bit bus along with a few timing/sync signals interconnected a
4004 and multiples of the 4001/2. Address and data were muxed through the bus
in a somewhat complex sequence. The 4001/2s were hard-programmed with address
range and I/O port numbers to respond to.
The 4008 & 9 were introduced later, and were in larger packages, they demuxed
the bus/machine cycle into wider,separate address/data lines to permit use of
more-conventional RAM/ROM/EPROM chips and easier I/O.
The mask-programmed 4001/2 made it all essentially inaccessible to hobbyists but
the small packages and high level of family integration actually did make for
very compact systems.
Regarding the 4040, I'm speculating as I've never dealt with one or come
across the pinout, but I suspect the 4040 essentially integrated the
4004/4008/4009 into one larger package making it look more like a 'standard'
microproc in terms of signals/interface (somebody correct me if I'm wrong).
Perhaps not speed as an issue but you were wired
into the small family of
chips that understood the highly specific machine/bus cycle, at least
until the 4008/9 came along that broke out the address/data busses.
4008/9? First I've heard of these at all.
Can you give any sort of a general overview of what those parts were all
about?