[geeks] Mac definitions

[Nemo]

On 8 July 2011 10:12, Phil Stracchino <alaric at metrocast.net> wrote:
> On 07/08/11 08:10, Nemo wrote:
>> On 7 July 2011 21:30, Sandwich Maker <adh at an.bradford.ma.us> wrote (in
part):
>> [...]
>>> - never mind reprogramming - is out of reach of the average weekend
mechanic.
>>
>> I am reminded of a friend 15 years ago who replaced the ROM in his
>> car's ECM with his hacked version.  The results were not quite what he
>> expected.
>
> Inquiring minds would love to hear the rest of the story...   :)

He is a embedded-computer engineer with no inside knowledge of the
car.  He noticed the ROM, popped it out, and disassembled the
contents.  (AMC used 68k chips in those days with which he was quite
familiar.)  Believe it or not, he *guessed* what parts of the code did
what and "improved" it -- decreasing loop counts, increasing output
values.  He burned an EPROM and popped it in -- the car would not even
start.  A few more iterations and the car started but idled rather
wildly.  Engine fluctuations were too great to even drive it.  He gave
up and put the original ROM back.  However, his tinkering seems to
caused problems because some extensive work was needed by a garage
before the car could be driven.  I never asked -- he was sufficiently
embarrassed not to want to discuss it anymore.