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Re: On attempting to make the 3.5" floppy adaptor to work...

Tristan Mumford wrote:

Michael J. Mahon wrote:



Tristan Mumford wrote:


<snip>


I also managed to turn an 18f452 into a nice heating element. When I did
the reshuffling I managed to short the -12v to one of its IO lines, which
would have resulted in a nice 17v potential difference inside the chip.
Or is it 16v. Doesn't matter anyway. Now I have something to throw at the
neighbours cats.


Aaaack.  ;-(



I believe I measured a whopping 12ohm resistance between Vdd and Vss.

Paranoia now has me keeping my finger on top of the uC the whole time it's
on feeling for a temperature difference.


Been there--even slightly burned my finger!  ;-)


Just the other day, I found an Apple ][+ ROM (the E8 ROM) that is
a near short from +5v to ground--it also makes a nice heating element!

This is the first time I've found a ROM with this failure mode.



Was the extent of the failure isolated to the ROM? I'm surprised too that it
died. Electronics don't come much more robust than a ROM.


I was amazed.  That was the only failure, though it may have induced
the power supply to fail (it doesn't work).



Glad you think so. Do you think that using a soft encoding method like I
attempted is wrong? I have my doubts about it. It's just it was easy to
modify my board to try it so I did.

To do it I disconnected my erroneous connection of the write signal from the
hex inverter and connected it to the uC. I also connected a pin of the uC
to the write enable pin so I could get feedback on when it wants to write.


How fast can the controller poll the input and produce an output?
The write signal should be on time within a fraction of a microsecond.

-michael

NadaNet networking for Apple II computers!
Home page:  http://members.aol.com/MJMahon/

"The wastebasket is our most important design
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