Resetting C= machines with non-standard implements (was Re: Are you sure the 6550 is dead?)
22 Mar
2000
22 Mar
'00
3:25 a.m.
--- Philip.Belben(a)powertech.co.uk wrote:
If I've got to the point where I need to hit RESET, it doesn't matter.
It doesn't matter to the software, but there's the risk of shorting things
together that don't want to be shorted.
The old
PETs don't AFAIK have the internal expansion connector - they have
an edge connector sticking out at one side. Very useful for toggling
RESET with a pair of tweezers!
Don't miss! Occasionally I corrupted I/O registers and disabled
the interrupts that
serviced the keyboard. You'd better not miss when toggling IRQ with the
tweezers!
I used to reset my development C-64 with a paperclip that I bent into a
hair-pin shape with a .3" or .4" spacing to fit the proper pins on the
expansion connector. I even melted a drinking straw and wrapped it around
the top of the loop for a "handle". It was my programmer's reset for
years.
-ethan
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22 Mar
22 Mar
4:04 a.m.
::I used to reset my development C-64 with a paperclip that I bent into a
::hair-pin shape with a .3" or .4" spacing to fit the proper pins on the
::expansion connector. I even melted a drinking straw and wrapped it around
::the top of the loop for a "handle". It was my programmer's reset for
::years.
I've seen people burn out 64's that way too :-P
--
----------------------------- personal page: http://www.armory.com/~spectre/ --
Cameron Kaiser * Point Loma Nazarene University * ckaiser(a)ptloma.edu
-- FORTUNE: Don't abandon hope: your Tom Mix decoder ring arrives tomorrow. ---
8:16 a.m.
Hi,
Quite, I've got to say this is an EXTREMELY BAD way of resetting a C64 in my
experience.
At one software company I worked at in 1986 we made up reset switches for
our C64s to save wear and tear on them - we were using the machines in
pairs; one to assemble/edit code, the other to test the code (which needed
frequent resetting). Some of these had the switch attached to the user port,
the rest had it connected to the reset line on the serial port (we built
little push switches into DIN plugs and just plugged them in).
Within three months of these switches being fitted ALL of the machines with
reset switches failed (with dead processors).
Obvious why really....you don't EVER connect something which is capable of
generating voltage spikes to a TTL line - this includes tweezers and paper
clips....
TTFN - Pete.
--
Hardware & Software Engineer. Sound Engineer.
Collector of Arcade Machines, Games Consoles & Obsolete Computers (esp DEC)
peter.pachla(a)wintermute.org.uk | www.wintermute.org.uk
--
I used to
reset my development C-64 with a paperclip that I
bent into a hair-pin shape.... ....fit the proper pins on the
expansion connector....
I've seen people burn out 64's that way too :-P 
10:33 a.m.
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11:30 a.m.
I had a C64 on which I installed a reset switch into my HES-MON assembler
cartridge. I used it for several years that way. I eventually gave the
64 to my nephew and I believe the machine still works to this day,
although I doubt the HES-MON got much use after I gave it away.
I did manage to fry a couple of sound chips, probably by feeding too many
nasty signals through the (band-pass?) filter input on the sound DIN.
In college I picked up a discarded Televideo 950 terminal with a 6502
processor. It had a habit of hanging on invalid escape codes, so I
soldered a momentary push button switch on its reset pin. It also
continued to work up to being discarded.
The capacitor probably would have been a good idea in either case.
Paul
On Thu, 23 Mar 2000, Tony Duell wrote:
Quite, I've got to say this is an EXTREMELY BAD way of resetting a C64 in my
experience.
Yes, but I would have thought that the main problem is that you're
effectively shorting an output (namely the output of the chip that
normally generates the reset signal) to ground. This is not generally a
good idea.
I am suprised it was the processor that failed, though. AFAIK, the
processor in a C64 never outputs anything to the reset line.
There's a fairly easy modification IIRC that adds a reset switch in
parallel with a capacitor in the reset circuit. This is a safe way to do
it. It's fairly obvious how to do this given a C64 schematic. If anyone
is seriously interested, I'll see what I can find.
-tony
11:44 a.m.
New subject: Resetting C= machines with non-standard implements (was Re:
On 23-Mar-2000 Tony Duell wrote:
http://www.funet.fi/pub/cbm/documents/projects/other/reset-for-64.txt
claims it's pin 8 of U20, a 556 timer IC. I think adding a cap would be
useful for debouncing.
BTW, where would one find a connector for the user port on a C-64?
-Philip
Quite, I've got to say this is an EXTREMELY BAD way of resetting a C64
in my
experience.
Yes, but I would have thought that the main problem is that you're
effectively shorting an output (namely the output of the chip that
normally generates the reset signal) to ground. This is not generally a
good idea.
I am suprised it was the processor that failed, though. AFAIK, the
processor in a C64 never outputs anything to the reset line.
There's a fairly easy modification IIRC that adds a reset switch in
parallel with a capacitor in the reset circuit. This is a safe way to do
it. It's fairly obvious how to do this given a C64 schematic. If anyone
is seriously interested, I'll see what I can find.
-tony
12:09 p.m.
New subject: Resetting C= machines with non-standard implements (was Re:
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12:36 p.m.
New subject: Resetting C= machines with non-standard implements (was Re:
::http://www.funet.fi/pub/cbm/documents/projects/other/reset-for-64.txt
::claims it's pin 8 of U20, a 556 timer IC. I think adding a cap would be
::useful for debouncing.
::
::BTW, where would one find a connector for the user port on a C-64?
I either steal them from old modems, or look at
http://www.retrobits.com/ckb/display.cgi?75
for the DigiKey part #.
--
----------------------------- personal page: http://www.armory.com/~spectre/ --
Cameron Kaiser * Point Loma Nazarene University * ckaiser(a)ptloma.edu
-- Please dispose of this message in the usual manner. -- Mission: Impossible -
4:57 p.m.
New subject: Resetting C= machines with non-standard implements (was Re:
On 23-Mar-2000 Cameron Kaiser wrote:
::http://www.funet.fi/pub/cbm/documents/projects/other/reset-for-64.txt
::claims it's pin 8 of U20, a 556 timer IC. I think adding a cap would
::be
::useful for debouncing.
::
::BTW, where would one find a connector for the user port on a C-64?
I either steal them from old modems, or look at
http://www.retrobits.com/ckb/display.cgi?75
for the DigiKey part #.
Very cool. Thank you.
-Philip
23 Mar
23 Mar
8:57 a.m.
New subject: Resetting C= machines with non-standard implements (was Re:
Hello Cameron
On 22-Mar-00, you wrote:
::http://www.funet.fi/pub/cbm/documents/projects/other/reset-for-64.txt
::claims it's pin 8 of U20, a 556 timer IC. I think adding a cap would
be
::useful for debouncing.
::
::BTW, where would one find a connector for the user port on a C-64?
Try contacting Gateway electronics in St. Louis -- they have a lot of really
obscure parts . . . .
Gary Hildebrand
24 Mar
24 Mar
6:13 a.m.
Hi,
Yes, but I would have thought that the main problem is
that
you're effectively shorting an output....
Actually, I hadn't thought of that. It's a good point.
I am suprised it was the processor that failed,
though. AFAIK,
the processor in a C64 never outputs anything to the reset line.
Well, I didn't actually do the fault finding on these machines myself. But
the chap who did repair them said he'd had to replace the 6510s.
I assume that spikes from the unbuffered switches had fried the 6510s reset
circuitry...?
There's a fairly easy modification IIRC that adds
a reset switch
in parallel with a capacitor in the reset circuit....
As you say, that's the best way of doing it.
TTFN - Pete.
--
Hardware & Software Engineer. Sound Engineer.
Collector of Arcade Machines, Games Consoles & Obsolete Computers (esp DEC)
peter.pachla(a)wintermute.org.uk | www.wintermute.org.uk
--
9040
days inactive
9042
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10 comments
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