Re: A86: im 0

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Re: A86: im 0


At 23:56 1999-01-14 -0500, you wrote:
>
>The following code should count the number of interupts that occur
>within a certain amount of time (but it doesn't).  So, have I done
>something wrong, or am I mistaken about what im 0 does?  Dux's tutorial
>says it executes the code contained in the i register...

That's very wrong. The code that gets executed is the opcode that
currently lies on the databus. Since that opcode can be anything
(ie random) you will cause (in 99%) a crash. The I register is
for im 2 only.

Note: On some systems which doesn't have support for im 0 (ie TI-85)
the CPU will put $FF on the databus (==nothing) which gets executed.
$FF = rst 38h => im 0 == im 1. But that's not the case on the 85
I believe.

//Jimmy Mårdell

E-mail: yarin@acc.umu.se
Homepage: http://www.acc.umu.se/~yarin/
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