I suggest if you are interested in this system you make
   a folder and drag over all the many future messages on this
   subject otherwise delete it.

There are at least two ways to build an EFI program.
The first and the simplest is to assume power is a direct
function or RPM and manifold pressure. That is how a 555 system
works. The injector is triggered once per revolution
and the pules width is controlled the manifold pressure.
The higher the pressure the wider the pulse... more fuel.

See http://www.rotaryeng.net/simple-cheap-555.html

To do that using a computer programed in BASIC is trivial.
Almost a waste of the computer's power. I could write
the program in about five minutes. Maybe a day at the most.

The vast majority of EFI systems and that includes Tracy's system
use a look up table to adjust the injector pulse  width for
a given RPM and manifold pressure.  That gives a 2 dimensional
table of several hundred entries. One could have a one dimensional
table for say 75 different RPMs and modify the table values
by the manifold reading. That would be say every 100 RPM
for the rotary. I am not sure which system Tracy's
uses. One can do a bit of math and interpolate between
fixed readings. The same thing could be based on manifold
pressure alone and adjusted by intake air temperature.

The table is stored in EEPROM so it is always there even if
the power is turned off. In ZBasic speak that is called
persistent memory and there are 4000 bytes available.

Fortunately ZBasic has 2 Routines that are highly
useful in this sort of EFI system.
PersistentPoke(value, address) and PersistentPeek(address)
See page 182 of the ZBasic System Library  Reference Manual.

The address is just the line number of a one dimensional
table. The value at that address is a Byte data type
being 0 to 255. See page 7 ZBasic Language Reference Manual.

Poke can load the table from a file in your PC computer
you generated with an editor. If you used two ZX computers
such as Tracy does you could fly on one while adjusting
the other using a NetBook and switch in the air. It helps
if you have an autopilot or some one else to fly the plane
and look out for traffic.

Peek of course can read the file for a given RPM
and use that number adjusted by the MAP to control
the injector width.

Peek can also be used to read out the file to your
PC just to check up on what is in there in case you
forgot.


Paul Lamar