1227727 vs 16149396

Ludis Langens ludis at cruzers.com
Thu Nov 5 05:36:32 GMT 1998


A while ago, I asked about the second of the above two ECMs.  The
16149396 turns out to be a 1227727 with some extra SRAM.  (The '7727 is
the underhood version of a 1227730 ECM.)

The '9396 populates three chip locations which are empty in a '7727.  U3
is an industry standard 2K byte SRAM in a 24 pin 0.6" DIP package.  The
GM part number is 16045908.  U4 is a 74*138 style 3to8 decoder in a SMT
package.  The GM number is 49227 (or 16049227 ?).  U8 is a 74*00 NAND
gate, also in a SMT package - number 49228 (or 16049228 ?).

U8 generates ~OE and ~WE from the 68xx R/~W and E signals.  U4 generates
a ~CS from the upper address lines.  It maps the SRAM into memory in the
range $1800 through $1FFF.  For some reason, the ~CS, ~OE, and ~WE lines
all have a series resistor.

Now, the 64 bit question is, what's the service number of a 1227730 with
this extra SRAM?

-- 
Ludis Langens                               ludis (at) cruzers (dot) com
Mac, Fiero, & engine controller goodies:  http://www.cruzers.com/~ludis/





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