Re: [cosmacelf] Re: membership card
- Here's another idea
> - RS-232 port (bit-banger using Q and EF4)I don't know how easy it is to make a bit-banged RS-232 port. But you could
instead make a bit-banged I2C bus and use an I2C eeprom. Those are generally
DIL8 chips and don't take up much space at all.
You would then also already have the I2C bus to connect the Nokia display.
How large would an I2C bootloader be? Could it be toggled in by hand in a
short time? Then you could pre-load the eeprom with all sort of routines.
You could then toggle in the bootloader which copies the eeprom to ram, and
then you could boot from ram.
The stacking-boards design sounds very nice, by the way. At those low
frequencies I don't expect any real problems.
- --- In firstname.lastname@example.org, 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.