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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