Re: [cosmacelf] Re: membership card
- rileym65 wrote:
> Just to put my .02 into the conversation, I think a clearer, easierAgreed. So, what is a "good" size? Playing-card sized? 3"x5" card sized?
> circuit design is far preferable to small size.
What sorts of standard common boxes come to mind?
> I could really see for tiny sizes if you are using them as embeddedWell, one of the things I am interested in are "beam" robots; tiny
light-powered autonomous robots. While there are dozens of BASIC
Stamp-like microcontrollers, none of them are within orders of magnitude
of being as low-powered as the 1802.
> when talking about something a beginner can put together and use,Hmm... how about this then?
> embedded controllers are just not part of the equation. Better to
> design a board specefically to that task, in which case all you
> would need is the cpu, ram, rom, 8-bit latch and i/o connector.
> That could be done in really small space for those who are after
> an embedded controler.
Suppose the "system" consisted of TWO boards; an "application" board
with the CPU, memory, and I/O -- and a "development" board that has the
front panel switches, displays, etc.
This doubles your overall PCB area without making the final package much
bigger (only thicker). Parts are spread out more, so each board is
easier to build and layout.
The application board has:
- 1802, crystal oscillator, and power-on-reset
- two bytewide RAM/ROM sockets
- 8-bit input port
- 8-bit output port
- RS-232 port (bit-banger using Q and EF4)
The development board has:
- 1802, adjustable RC oscillator
- Elf toggle switch front panel (8 Data, Load, Run, Protect, In)
- Elf hex display (or 8 individual LEDs)
- 256 bytes RAM
Here's the tricky part. Each of these boards is a fully operational
stand-alone 1802 computer by itself. But, you can plug them together to
make a more powerful system.
I suggest using the 1802 socket itself as the bus connector that
interconnects the boards. I did this at TMSI for the "Proteus" and it
was very handy. Each board has a 40-pin IC socket with ~0.5" long pins.
The 1802 itself plugs into the top of this socket.
Additional boards are "stacked", with the long pins of the 1802 socket
of one plugging into the 1802 socket of the next. There is only one
1802, which goes in the top socket.
Let's say we have an application board that we need to debug. Build the
development board with its toggle switches and LED displays on the
"back". Plug it onto the long pins of the application board, and you
have a 2-board stack. It has all the I/O and memory of both boards. The
front panel can examine and load programs, to help figure out what is
How does that sound?
"The two most common elements in the universe
are hydrogen and stupidity." -- Harlan Ellison
Lee A. Hart 814 8th Ave N Sartell MN 56377 leeahart_at_earthlink.net
- --- In email@example.com, Lee Hart <leeahart@e...> wrote:
> One more thought. Can someone who has any of the skinny-DIP 28-pinLee, they run the gamut from cmos parts in the few mils range to
> thru-hole 32k RAMs actually plug one into a breadboard and see how much
> power they really take? If we can find one that is reasonably
> inexpensive and available, we could use it on the MEMBER card to save a
around 100ma for the older nmos designs. I have some Alliance CMOS
parts pulled from a 486 cache and they run about 12ma when supporting
a z80/4mhz. Their drain is cycle time dependent for the cmos. I've
looked and the general xx256 parts are still fairly easy to find and
cheap. Do watch for the parts that are semi-static where the address
lines are latched by CE/. Their power drain is very low but CE/ must
be asserted for every access.