On Sat, May 29, 2004 at 05:46:03PM -0700, Ron Hudson wrote:
> How rare are elfs? How about 1802s, could I build my own?
Not sure how rare, but the 1802 is still in production (~$50), or you can
find them for a lot less than that on ePay. What's rare is the 1861 "Pixie"
video chip.
I built a Popular-Electronics Elf here at Pole. I brought down the processor
and many of the parts when I arrived, and ordered what I was missing while
we still had daily flights. I finished the circuit about six weeks ago, but
I still haven't found black paint to finish the switch panel. It runs, but
I'm not ready to take pictures of it yet.
If you aren't trying to make a picture-perfect replica of the one in the
magazine, all you need is a hunk of perf board, a handful of sockets, some
resistors and diodes, 11 toggle switches, 1 push button switch, a +5V power
supply, and a few chips (1802, SRAM (1822/5101/2101 were used 28 years ago,
but even a 2016 or 6116 would work), 2 x 4016, 2 x 4050, 4049, 4013, 4023),
either a pair of hex displays (like the TIL311) or a slightly different
circuit and 8 LEDs, and a clock. The two most popular frequencies are 1MHz
and 1/2 of 3.579545 MHz. The P-E Elf started out at 1MHz and switched to
1.79MHz to accomodate the 1861 (by adding a 3.579545MHz crystal, a 74L00
used as an oscillator, and a 7474 to divide by two). The ACE designs
specified 1.79MHz. Toggle-in programs expect one of the two frequencies.
If you want to get fancy, you can hook interesting things up to the Q line,
like a speaker or a relay. You can also latch some of the upper address bits
and have more than 256 bytes of RAM, but that's a lot of toggling.
There's an active Yahoo! Group about the 1802...
http://groups.yahoo.com/groups/cosmacelf
Folks are discussing new designs, there was a thread last year about reverse
engineering a hand-held factory "palmtop" computer (the size of a *large*
calculator) that some of us bought surplus for $4 each, there's even some
people from the old days that are still around and still working with the
1802.
I think you have to sign-on to access the pictures and download files (one of
the pictures in the gallery is of my Quest Elf I built as a kid).
-ethan
--
Ethan Dicks, A-130-S Current South Pole Weather at 30-May-2004 02:40 Z
South Pole Station
PSC 468 Box 400 Temp -76.2 F (-60.2 C) Windchill -125.3 F (-87.40 C)
APO AP 96598 Wind 20.8 kts Grid 358 Barometer 664.3 mb (11225. ft)
Ethan.Dicks_at_amanda.spole.gov http://penguincentral.com/penguincentral.html
Received on Sat May 29 2004 - 21:57:55 BST