6562Re: [cosmacelf] Re: Membership Card - Ultra Low Power Variant
- Mar 1, 2010aa3nm wrote:
> My goal is to have a truly minimum power ELF that is as simple asYep; me too! But, it's a heck of a lot less painful with good switches.
> possible with binary input and output. That being said, the tedium
> of programming anything more than ~50 bytes gets old very fast, even
> with toggle switches (been there too).
Use the best, easiest-to-use switches you can find. Notice that many of
the traditional minicomputer front panels and organs use piano key like
Same for a display. 8 raw binary LEDs are simple and cheap, but have few
other attributes. The LCD display is lower power, and can produce a much
The small step up to a hex keypad and hex display is a big improvement
You might also consider adding a circuit so a PC's parallel port can
manipulate the front panel switches, as a way to automate the
Other thoughts: I don't think nearly enough creativity has been applied
to the data entry and display issue. People quickly fixate on the
antique QWERTY keyboard and video text displays. They work , but it
takes a *lot* of hardware and software to support them.
How about some of these alternative, just for fun... :-)
- Morse code. A single switch contact is all you need for input.
One bit to drive a speaker is all you need for output.
The software to read and write Morse code is trivial (ham radio
operators have written it many times, so examples are plentiful).
Morse code (especially for numbers) isn't very hard to learn.
- Voice. Pick 16 audio tones to represent each hex digit 0-F. Whistle
or hum them to input data. A microphone and simple hardware/software
interprets the tones. Play the same tones back to read the data.
Has the advantage that it can also be saved and loaded with a tape
recorder or PC sound card. You "sing" to your computer, and it "sings"
back to you, like R2D2.
- Calculator. A calculator has special keys for each function; + - /
sin, square, etc. So, have keys labelled PHI GLO BR etc. and an
alphanumeric display that shows assembler mnemonics.
- Graphics and light pen. The display is a printed drawing of the 1802
architecture, with a single LED at each register, and perhaps 24 LEDs
showing the current memory address and its contents. A light pen
(just a phototransistor in an old pen body) connects to an EFx line.
Poke LEDs to turn them on/off, or move data to/from registers I/O
and memory. The LEDs are multiplexed, so the time at which the light
pen sees the pulse of light tells it which LED you pointed at.
- Mouse with a view. House the ELF in an old computer mouse case.
Attach a little plexiglass window that has an LED/LCD display.
Set the mouse on a printed drawing of the computer architecture.
As you move the mouse over a box on the drawing, the display on the
mouse shows you the contents of that box. Aim at Register A, and it
displays the contents of RA. Needs a mouse that doesn't "slip", or
is reading codes printed on the page to know where it is. Use the
mouse buttons to increment, decrement, scroll wheel for faster
up/down changes, or to drag data from one register to another.
- Analog meters and pots (a steampunk Elf). A pair of analog meters
are marked 0 to 15v. A simple D/A converter converts the two hex
digits you get from a typical Elf into two voltages ("A4" displays
as 10v on the left meter, 4v on the right meter). Two pots or
rotary switches under the meters are similarly labelled 0-15v.
Use knife switches for the load/run switches.
> BTW, I know you did a lot of work on the power consumption of theLCDs vary a lot. The older simpler ones (no backlight, no color, not
> membership card - Do you have any sense on the consumption of this
> layout? I read on Herb's page that you were "running air" on the
> membershiip card overnight from the charge in the .047 uF cap, but
> adding the LCD display bumps up the power consumption (a lot less
> than LEDs but its still there).
multiplexed) are very low. The Lumex display on the LCD Elf I posted
will probably run on less than 10 ua.
Pullup resistors and memory chips are likely to be your the biggest
problems. You need a design that avoids pullup resistors. The old 5101
chips I used are true CMOS; zero power consumption when all inputs are
static. but almost all modern RAMs (even those claimed to be CMOS) draw
a significant supply current when chip selected even if all inputs are
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