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Re: Apple //c, 255 version: rare?

On 8/6/2010 6:05 AM, The Elfe wrote:

"Michael J. Mahon"<mjmahon@aol.com>  wrote in
NMWdnfCwy4mjKMbRnZ2dnUVZ_g6dnZ2d@giganews.com:">news:NMWdnfCwy4mjKMbRnZ2dnUVZ_g6dnZ2d@giganews.com:


On 8/5/2010 11:03 PM, The Elfe wrote:

"Michael J. Mahon"<mjmahon@aol.com>   wrote in
g7-dndafytxF98bRnZ2dnUVZ_rmdnZ2d@giganews.com:">news:g7-dndafytxF98bRnZ2dnUVZ_rmdnZ2d@giganews.com:


On 8/5/2010 9:23 AM, The Elfe wrote:

Mitchell Spector<mitch2gs@hotmail.com>    wrote in
lk6k569vb7hjf7e35410crf0c48jlhdkcp@4ax.com:">news:lk6k569vb7hjf7e35410crf0c48jlhdkcp@4ax.com:


The Elfe<email@nospam.com>    wrote:



       Less common to find, at least in my experience, is the

original

       IIc
motherboard with serial port timing glitch (identified by the
presence of a 72LS161 chip rather than a tin oscillator). Also less
common is a IIc with the 'ROM 4' firmware. Or better yet, 'ROM 5',
which is the IIc Plus. :) None of these are rare per say, just less
common.


I'm living in Europe.
Mine has 2 problems: one is when I press CONTROL+RESET, I could
nothing type, for the cursor was moving endless

>from time to time with some strange patterns and some beeps. Well

I

have

to find another motherboard, I think, aye.


       Sounds like certain keys are stuck, either physically or due

to

the fault of failed circuit logic, like the keyboard encoder chip.

       The original ROM (255) had no built-in self test diagnostic,
however if you pressed Apple + Control + Solid-Apple you'd
get something like you describe. Could be the Solid-Apple
key is stuck, or shorted because of an attached joystick.

       Could also be bad DRAM's on the motherboard, though
the only way to tell is to run a floppy disk based diagnostic.
I'd recommend the Apple II Diagnostic from Apple.

Mitchell Spector


Well, the original ROM (255) has a "almost"built-in self test
diagnostic... but neverending. I know that I can start the
diagnostic, stop the working disk drive. So it could be a bad ram or
keyboard encoder chip. is there a means to check this chip?

Thank for your help,
The Elfe

Well, I tried with another working keyboard. What would happen if I
remove the keyboard chip, then switch on the Apple 2c?


If the encoder is the problem, that should make the machine boot
normally.

-michael

NadaNet 3.1 for Apple II parallel computing!
Home page:  http://home.comcast.net/~mjmahon/

"The wastebasket is our most important design
tool--and it's seriously underused."


Thanks.
Could I do remove this keyboard chip without any damage to the Apple 2C?


Sure--particularly if it's socketed.

-michael

NadaNet 3.1 for Apple II parallel computing!
Home page:  http://home.comcast.net/~mjmahon/

"The wastebasket is our most important design
tool--and it's seriously underused."