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Home » Digital Archaeology » Computer Arcana » Commodore » Commodore 8-bit » [WTB] TED 8360 and PLA for Commodore 16/116
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Re: [WTB] TED 8360 and PLA for Commodore 16/116 [message #210379 is a reply to message #210356] Sat, 26 October 2013 21:13 Go to previous messageGo to previous message
George is currently offline  George
Messages: 80
Registered: February 2013
Karma:
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address_is@invalid.invalid says...

> Those chips, especially TED, were not built to last.
> They fail in every 264 series machine If you are lucky
> you may buy a working C16 for the price some dudes ask
> for TED alone :-(

Nah. I've had a Plus4 running continuously since 1992.
It's my caller ID computer. And it still runs fine.

I've always felt that CBM computers in general were subject
to damage caused by power glitches and a resulting
collision in which two or more chips end up trying to drive
the address or data lines at the same time, which should
never happen normally, but can happen when the power
flutters and the chips get confused.

So I added a Max 690 circuit to my Commodores. That's a
little 8-pin watchdog chip that pulls a hard ground on the
*Reset line when Vcc drops below about 4.5V, which turns off
all the line drivers of the various chips, and holds *Reset
low until Vcc has again stabilized at 5V for a period of
time. Seems to work well to prevent power glitches from
causing damage.

Of course I can't prove this theory, but, you know, 1992.

By the way, with respect to looking for replacment chips,
it's possible that a number of the major chips
are the same in the C16 and +4, even including the PLA. As
I recall, the kernal determines whether it's running in a
C16 or +4 based on how much ram is present, or something
similar.
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