The Killer POKE

Bill Gates is responsible for the Killer Poke

Shorting an output of a TTL chip (like 74LS08) to ground is harmless

Can you use the crt seperetly

Shelby you're wrong, I ran the poke on my PET and it caught fire, burned my house down, robbed my mother, screwed my wife, kidnapped my children and poisoned my towns water supply.

Please do your research next time.

My brother (who is a computer programmer and expert) told me once that a computer can be destroyed with a few BASIC instructions (perhaps he was refering to the "poke" one)

I can't remember what poke I used, so many years ago, but I made a double Dragon clone where the screen looped around and I could draw over it, so I used it to make the background.. I probably only used text base graphics for the game .. I don't have one anymore to try and show you guys what I mean, but it was cool!

My recollection of why the "killer poke" was dangerous was that it was valid only for later PET's that had video logic that was based on an 6845 CRT controller, and the story was that you could manipulate a register of the 6845 so that it increased the frequency of the horizontal sync, this would increase the frequency of the horizontal sweep gnerator which would increase the voltage of the high voltage generator to a point that it dramatically started to spark inside and that COULD damage your PET. Maybe it isn't the same poke shown here, just that such a poke could exist on a PET.
But then the 6845 was used in many other video cards especially those used in PC's, like the CGA, EGA and many other video cards, and I have never heard of a killer poke (or OUT command) for these so perhaps it was an urban legend after all. by the way, the poke that drove an I/O pin low against an 7408 could be simply solved by adding a small resistor (470 Ohm or so) so that the PIO's output or the 7408 would not be damaged by this I/O conflict, the 470 ohm would do nothing when the I/O was used as input, but when reprogrammed as an output the 470 Ohm would significantly lower the output current outputted by the I/O pin.

I remember hearing about this as an urban legend when I was in computer class as a junior in high school, in 1982. The way my teacher explained it, this command had the power to melt down your computer like something in a Star Trek episode.

Compatibility isnt a issue, if you run exactly same system as i have, says devs back in the day
. And read the manual, there was documented all the things what you need modify before running the applications :D

Thank you for the update. It toke human kind 10 years to anderstand what the killerpook is and 30 years to anderstand what It does

Of course, the oscilloscope deflects the electron beam with an electric field rather than a magnetic field so it can respond to faster signals.

What is that red thing on the shelf over your right shoulder? It looks so familiar!
EDIT: Nevermind, I found out it is a "Merlin" Electronic game 1978.

I managed to kill my Hercules monitor 3 times by blowing the fuse. When switching from text mode to graphics mode, you must set the registers in a certain way within a certain time period otherwise you will damage your monitor (popping the fuse)

Today i learned: 3 isn't a prime number 🙂

Where's his friend Garth?

Fortunately... a 74LS08 is not a hard chip to replace. Or a 65C22 for that matter.

In addition to that killer poke it looks like someone applied a killer punch to the screen bezel.

due to cbm (and also atari's ;) tendency to use 'universal' i/o chips all over the place i'm pretty sure one can find a gate programmable as an output that is either connected to another gate connected as an output or some ground or vcc line through a dipswitch without protective resistors or whatever resulting in a short in quite a number of periphials. what on earth these people had against simply using an 8 bit latch as either an input or output port (without data direction register ;) is beyond me :P but yeah. pretty sure there is hell a lot more than the killer poke that violates the 'nothing you can type into the computer can break the computer' stuff they claimed. potentially also plenty of stuff that while it's still on still has a 1 on some input/output line (to a computer that is off, or the other way around) and as such that input/output line is 'higher than vcc' thus operating out of spec. maybe all the computers nicely have resistors on all such things but the diskdrives and printers and stuff which usually are also reprogrammable in circuit and also literally plastered with 6520's 6522's 6530s etc where a simple one way 8 bit latch would do..... usually are not that well thought of :P think things like 'device number jumpers'. all nice and well as long as the input, is always an input. but on anything with a data direction register, that can be reprogrammed from the computer itself it's not :P those serial busses also may nicely be open collector for some things... bbbbbut can happily be switched on other lines to just have a 1 output against a 0 output. although yes. the killer poke does involve just the computer itself as the screen is attached to the computer on a pet.... but you can bet your ass that in the 'larger ecosystem' of periphials there is plenty of stuff you can get to either destroy itself or other units. think i also fried some 6526'es and 6522's once by connecting 2 c64's to the same serial bus without a vic-switch in between and one was off. thus it somehow tried to power itself from the serial bus :P 'oops' :p you know it's generally better to just insert a proper hardware uart. a one directional output or input latch, an actual hardware shift register, etc than those things that try to be too many things to too many people and then having to take care that it doesn't blow itself up with all kinds of resistors and protection diodes if set up in some unexpected way. all the funnier when the protocol demands timers, and it turns out the firmware doesn't even use the timers from said chip :P LOL. then why even put that thing in there :P

it sounds like the story of a linux forced command to change a refresh to a crt screen that didn't support it, normally a screen would blank out like windows refresh change so not damaging the screen. but what if you force a old crt to display an unsupported mode - would it damage the monitor ? this was what I heard in the late 90s so I dont know if its a rumour but it sounds like it could be true technically speaking. I would be interested in the truth behind this.

Usually, it is not a good idea to connect two outputs together. But the original 6522 VIA has current limiting resistors in the output. So there is no real short circuit. The 7408 can drive this load without problems. The „Retrace“ bit at PB5 will be read as zero. So, it is disabling the „wait for retrace“ function in the PRINT.

With the modern WDC 65C22, it would be a problem, since this does not have internal current limiting resistors in the port outputs.

Love your shirt, bro.

My dad, a refrigerator repairman, had a Simpson multimeter just like the one over your shoulder. Good times!

My second computer in high school. The first was the smaller pet with the chicklet keyboard,

Whoever sais "only Pokémon 'Evolve'" is wrong.

But there was a Killer SYS comand !

In the 70s and 80s personal computers where only for the rich and affluent...............when this computer came out you could buy a new car for the same price , albeit it was a Ford Pinto or a Honda but in the 70s a car was far more useful than a home computer..................it was not till the 90s and Windows 95 before PC's went mainstream.

Facebook poke is the real killer

Again, do not try this at home as it will fry your PET.

pin15 lol

Adrian with a RPN calculator on his smartphone, fantastic!

The Serios Sam shirt made my day. Thank you for that.

There actually is a killer poke command, it would burn out your monitor, there was I guy in my class back in the 80's who did it. The poke command kept cycling the screen graphics to a pixel in the middle of the screen. I saw it in action, unfortunately I don't know what the command was or the name of the guy who did it.

"Two thousand eighteen..."

Try saying "TWENTY-eighteen" instead. It's shorter, so it's easier.

So what's the original value in that location, and what happens if you poke that back into it? And what about all the other values from 0-255?

"This is pretty much why we stopped writing in assembly for everything and created BIOS[es] and operating systems."
What? This is incorrect on a few levels: 1. We/they already weren't writing in assembly for everything. 2. It already has its OS! What do you mean by "why we... created operating systems" despite this computer already having one?

Tektronix 465... that's some seriously old test gear there..

Happy days PEEKing, POKEing my way round micros

It's time to upgrade to a digital oscilloscope lol.

"The killer poke... SWING!"

In college, a friend of mine told me that a friend of his made a POKE to ROM on his Atari and ruined the computer. Was that actually possible on Ataris?

Computer.

sudo rm -rf --no-preserve-root /

Way

Really enjoyed this. I remember reading about some computer that had a "killer poke" when I was a kid, but for years, I couldn't recall which one. The story I read was you'd burn out a chip with it, because you'd cause some rapid cycling that would overheat it. I see now the source of this lore was from the PET. I just remember this was one reason I dreaded delving into assembly language on a different computer, because I thought this sort of thing was a potential problem on many 8-bits, which is too bad, because once I got into 6502 assembly, many years later, it didn't seem that scary at all.

Well phooey, another legend from my childhood thoroughly debunked. ;-)

So - does this mean that you can run POKEMON or not on these machines? 😊