11 Aug
2008
11 Aug
'08
7:08 a.m.
From: ethan.dicks at usap.gov
Hmm... I happen to have a couple of 4004
chips (one pulled from a
non-UPC barcode scanner, the other from a commercial kitchen scale),
and I've long fantasized about building some showcase 4004 circuit,
probably a digital clock.
I don't happen to have the 4004 datasheet handy (and can't get to it
for a number of hours), but the -10V Vdd requirement makes me wonder
if it's possible/feasible to use a pair of ganged ICL7660s (still made
by Dallas/Maxim) to generate it. This chip came up recently as a
possibility for generating -5V Vdd for 4116 DRAMs (and I think the
concensus was that it would probably be adequate for up to 16 chips),
so I do recall that it can only source a few mA (each 4116 needs a
few dozen uA)...
I don't see a GND pin on the 4004, so I'm at a loss to estimate
what it would require for Vdd. Anyone know or can check easily?
Also, does anyone know about any sort of 4004 emulator or simulator?
I wouldn't mind trying my hand at some code *before* trying to build
out the hardware.
-ethan
Hi Ethan
The chip is P-mos and it doesn't directly connect to ttl.
The down is very week and only pulls up with any
strength.
There were a couple chip interfaces ( 4008 and 4009 )
that created TTL level signals to run standard RAM/ROM.
The only issue here is that one lost the instruction stream
so that one couldn' t take advantage of any RAM ot ROM
specific commands.
The later came out with a single chip version of the
interface( I think it was 4269 ).
These come up on ebay every now and then.
The manual on Al's site shows a circuit to convert the Pmos
levels to a TTL eprom ( used on the SIM4-1 ). The circuit does
use 4002-1 and 4002-2 RAMs.
The 4001/4002 had built in I/O. They would watch the instuction
steam and execute an I/O operation when the 4004 executed
the fetched instruction.
It is easier to modify a -12V supply to power the -10v than
to make a converter. Many floppy disk supplies are fine for
this.
Dwight
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