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The X-Philes (2nd Revision)
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The X-Philes Number 1 (1995).iso
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hp48hor2
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grobbug.doc
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1995-03-31
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46 lines
(Comp.sys.hp48)
Item: 380 by jmorriso@ee.ubc.ca
Author: [John Paul Morrison]
Subj: Dangerous Bug!
Date: Sat Dec 14 1991
I came accros this bug, quite unexpectedly.
This is on on HP48SX version E roms.
I have not tested any other roms.
I can rule out my own machine's corrupt memory as a possible
cause, since I can repeat the bug in a freshly memory cleared
machine.
If you enter this on the command line:
GROB m n (hit enter)
normally, it will create a GROB m x n which is blank.
if the dimensions are too big, you should get an insufficient memory error.
if m is any number and n is a number >= 2^20 - 10, watch out!
you will get a memory clear, and you will recover very little if any
of your original memory.
notice that if you interchange m and n, and enter GROB n m it will not crash,
but you'll get an out of memory error.
example:
GROB 1 1048576 (enter)
boom!!!
The bug can also be demonstrated by entering this:
"GROB 1 1048576" OBJ\->
in general: "GROB m n" OBJ\-> will cause a crash too, where m, n are the same
as before.
I'm fairly certain this has not been documented before. It is probable that
this bug exists on all ROMS but I'm guessing.
Solution: don't do it. It was bad luck that led me to discover this, and I
doubt if it will normally be encountered.
John Paul Morrison