Re: A82: Crashes!!!!!


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Re: A82: Crashes!!!!!



At 11:56 PM 10/6/97 -0400, you wrote:
>< Preventing a faulty program from crashing the calculator is virtually
>impossible.
>< If it writes garbage all over RAM, there's nothing the shell can do about
>it.
>
>Too bad the Z80 doesn't have protected mode.  Why couldn't TI have used
>286's?

PROTECTED MODE?!?!?  You have no idea what you are talking about.
Protected mode puts the CPU, on a PC, into 32 bit-full RAM access mode.  It
doesn't "protect" RAM like you may think it should (in fact, crashes are
frequent if the programming team had no idea what they were doing).  The
CPU is normally in 16-bit mode-64K page addressing.  The switch to 32-bit
mode requires quite a bit of knowledge of ASM coding.  What I mean by full
RAM access mode is that ALL RAM (every meg) is "changed" into one
continuous block of memory.  In order to use protected mode on a PC, you
have to have your own memory manager right in your own program or have an
external program (e.g. DOS4GW) take care of it.  There are several other
things that make protected mode special, but there is NO part of it that
protects RAM.  EVERY program ever made has a high probability that it has
some flaw that could cause the PC to crash.  EVEN protected mode programs
can mess up RAM and cause the computer to hang.  No programmer I know of
can make flawless code every time they sit down.

Besides, if I wanted a hand-held PC, I would've gotten it.  However, the
Z80 chip does just fine for me when it comes to both ASM and math.


                 Thomas J. Hruska -- thruska@tir.com
Shining Light Productions -- "Meeting the needs of fellow programmers"
         http://www.geocities.com/SiliconValley/Heights/8504
                    http://shinelight.home.ml.org


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