11 Aug
2008
11 Aug
'08
12:51 p.m.
On Mon, Aug 11, 2008 at 07:08:43AM -0700, dwight elvey wrote:
I do remember that it is P-MOS, but that's a bit out of my
experience - I got my start in the CMOS and TTL days of the
late 1970s. What little I know about older circuit types (RTL,
DTL, etc.) is from playing with DEC equipment.
I am not surprised to hear that it won't connect directly
to TTL, but I was thinking a 4007 or 4050 might do the trick.
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.
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.
OK.
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.
OK. I don't know if I have _those_ exact chips, but I do
have some support chips along with the processors.
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.
Those I have, at least one or two of.
The EPROM interface sounds quite useful - that was really my
worry since it's not possible to order genine MCS4-family
ROMs anymore.
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.
Right... I remember something about built-in I/O ports, but not
the details.
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.
Sure. I was just hoping to be able to dedicate a square inch or
two of the design and have a single-supply board. I also have
some +5V/-12V potted chargepump blocks at home, a remnant of
a particular COMBOARD design for a DEC chassis that lacked -12V
or -15V to run the EIA level shifters. Those might be able to
put out more than a few mA at -12V.
Thanks for the more detailed info,
-ethan
--
Ethan Dicks, A-333-S Current South Pole Weather at 11-Aug-2008 at 19:40 Z
South Pole Station
PSC 468 Box 400 Temp -78.7 F (-61.5 C) Windchill -123.7 F (-86.5 C)
APO AP 96598 Wind 15.9 kts Grid 13 Barometer 671.6 mb (10947 ft)
Ethan.Dicks at usap.gov http://penguincentral.com/penguincentral.html