Not 8-Bit, but I'm pretty sure you could do the same thing (well, the similar thing) to the IBM PC CGA monitor. You could screw with the counter(?) on the interface card and mess up the horizontal sync. If you didn't shut it off right away, it would burn itself up. Bill S. On 9/15/2026 3:27 PM, Sentrytv via vcf-midatlantic wrote:
Copied from one of the 8 bit groups. Was this the actual command?
“The PET-specific killer poke is connected to the architecture of that machine's video rasterizer circuits. In early model PETs, writing a certain value to the memory address of a certain I/O register ( POKE 59458,62 ) made the machine able to display text on the screen much faster. When the PET range was revamped with updated hardware, it was quickly discovered that performing the old trick on the new hardware led to disastrous behavior by the new video chip, causing it to destroy the PET's integrated CRT monitor.” Curious
Sent from: My extremely complicated, hand held electronic device.
On Sep 15, 2026, at 1:00 PM, Christopher Gioconda via vcf-midatlantic <vcf-midatlantic@lists.vcfed.org> wrote:
Passing this request along to the group: ~~~ A question for anyone who was there.
We are writing the October lead feature on whether software could ever actually damage 8-bit hardware, and the Commodore PET "killer poke" is at the center of it.
We have been looking for a confirmed case, and we cannot find one. Not a story about somebody's cousin's school. An actual PET that actually died and had to be repaired or replaced.
So here is what we are asking.
1. Did you personally see a computer damaged by a POKE or by a program? Any machine, any brand. What model, roughly what year, what failed, and what happened to it afterward? We are specifically after things you witnessed rather than things you were told.
2. If you typed the killer poke back in the day, what actually happened? Did the machine come back when you switched it off and on?
3. This one is a long shot and would make our year. We are trying to find the earliest place the poke appeared in print. One account has it circulating in a newsletter flyer that shipped with an order, as a tip to make a game run faster. If you have Commodore club newsletters, dealer flyers, or user group bulletins from roughly 1979 to 1981 sitting in a box, we would love to hear from you.
Please do not go and try the poke on your own machine to find out. The effect is almost certainly survivable, but there is a real possibility of long term stress from two outputs fighting each other, and no reason at all to risk a 45 year old computer for a magazine article.
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