730 vs 747 (was Re: Posted Tuning paper ...)

[Ludis Langens]

Joe Boucher <BoucherJC at lmtas.lmco.com> wrote:
> Here's some stuff I cut from the raw material Bruce orginally posted.
> Nothing better than
> his own words to explain!  The 730 and 747 are closely related aren't
> they?

The 730 and 747 are related, but only in the same way that a 4.77 MHz
8088 system is related to a 300 Mhz Pentium II system.  Actually, a
better comparison would be PC vs AT.  (The 1227148 ECM would be an XT.)

Looking at the wiring harness connector pinouts, the 747 seems to be
descended from the ECM used on the 1984 2.0 L4 TBI engine.  For 1985,
that ECM was changed to use an EPROM.  I would not be surprised if there
are no hardware changes between the '85 version and a 747.

The 730 is a member of the next generation of ECMs.  It has improvements
like a large EPROM, more RAM, a faster CPU, and SMD ICs.  Based on a
software comparison, the engine controller chip is similar, but some of
the control registers are moved around.

               unsigned long BinToBCD(unsigned long i) {unsigned long t;
Ludis Langens     return i ? (t = BinToBCD(i >> 1), (t << 1) + (i & 1) + 
ludis at cruzers.com            (t + 858993459 >> 2 & 572662306) * 3) : 0;}