Re: Two ways to torture a comp teacher

[fishern3485@cobra.uni.edu]

> To keep people from performing dastardly deeds, my high school computer
> lab ran a hacked version of BASIC in the language card.  It disabled
> POKE, PEEK, CALL, and every other command that you could use to disable
> the language card and get into "normal" BASIC, and hence into the system.
> 
> They left an intentional back door, however, which I managed to find: there
> is no bounds checking on PDL(). :-)

10 onerr goto 20
20 :
30 fart

that'll do it.  on the 85't error, basic will crash due to a bug in
the Onerr goto code that forgets to pull three bytes off the stack.
(call -3288 after the goto has executed to fix it)

There's also a very particular range of (large) line numbers that if
you try to list them, will crash basic.  Pity I can't recall what
they are.... (experament!  make an exe file to list every 256'th line)

also try ?usr(1) and that sometimes will do it.

-- 
Nathan Fisher
  FISHERN3485@COBRA.UNI.EDU