I know I am a bit late to the party (about 40 years late I guess) but here goes.
When I was 12 or so I discovered a bug in the TI BASIC interpeter on the TI-99/4A.
It would cause wonderful crashes, errors, hangs, dancing pixels, sometimes weird sounds and sprite shows and sometimes - a console reset.
It was an unintended demonstration of capabilities in stark contrast to the slow, limited, frustrating TI BASIC.
All you needed is a TI-99/4A console.
Instructions:
0. Power up
1. Fill the memory [buffer?] with some data
2. Enter an incomplete arithmetic syntax command, such as "a=a/"
3. Enjoy
For example:
would result in a couple of random pixels, and a stuck console.
And:
Would result in a couple of stationary sprites [?] with a dancing pixel show in them.
And a minimal "program" to launch some lively sprites:
If BASIC programs are loaded from tape, or entered and run, or the interpeter is loaded with a bit more text/history, a wonderful sprite show may result.
I never knew of GPL or VDP back then, all I wanted is to be able to program in assembly language or at least have PEEK and POKE like my buddies on their VIC20, ZX81 or C64s, but that was not to be.
Cartridges such as Mini Memory or Extended BASIC were very expensive so I never got one of those.
So - I could in principle make many sprites show up on my TV screen, but I had no control over how many, what they looked like, or what they'd do.
I have never seen a mention of this bug. Perhaps today those of you much more knowledgable in the memory structure of the machine can actually achieve proper sprite action or a proper jailbreak, and have some fun.
Some schreenshots attached for your enjoyment.
Good Luck,
-Alon.
When I was 12 or so I discovered a bug in the TI BASIC interpeter on the TI-99/4A.
It would cause wonderful crashes, errors, hangs, dancing pixels, sometimes weird sounds and sprite shows and sometimes - a console reset.
It was an unintended demonstration of capabilities in stark contrast to the slow, limited, frustrating TI BASIC.
All you needed is a TI-99/4A console.
Instructions:
0. Power up
1. Fill the memory [buffer?] with some data
2. Enter an incomplete arithmetic syntax command, such as "a=a/"
3. Enjoy
For example:
would result in a couple of random pixels, and a stuck console.
And:
Would result in a couple of stationary sprites [?] with a dancing pixel show in them.
And a minimal "program" to launch some lively sprites:
If BASIC programs are loaded from tape, or entered and run, or the interpeter is loaded with a bit more text/history, a wonderful sprite show may result.
I never knew of GPL or VDP back then, all I wanted is to be able to program in assembly language or at least have PEEK and POKE like my buddies on their VIC20, ZX81 or C64s, but that was not to be.
Cartridges such as Mini Memory or Extended BASIC were very expensive so I never got one of those.
So - I could in principle make many sprites show up on my TV screen, but I had no control over how many, what they looked like, or what they'd do.
I have never seen a mention of this bug. Perhaps today those of you much more knowledgable in the memory structure of the machine can actually achieve proper sprite action or a proper jailbreak, and have some fun.
Some schreenshots attached for your enjoyment.
Good Luck,
-Alon.
