Re: LZ: Disassembling
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At 05:51 PM 9/12/96 +0000, you wrote:
>> > I printed some of the ASM code out from the ROM, but does anyone know
>> > where the CPU starts when it is turned on??
>>
>> When the calculator is reset it starts from $0000, and probably also
>> when it's switched on after a "normal" switch-off. I'm not sure how
>> it works when it's "auto-powered-off" though.
>
>I figured that it started at 0000h when the batteries were taken out
>and it was fully reset. I traced it some and it just sets a bunch of
>stuff mentioned in some docs. I think that when you insert the
>batteries, it is turned on and it runs some code and then in
>immediately shut off because there is a halt command in there. I
>wanted to know where it started when it is turned on normally.
>
>-Ed
The HALT command just makes it dormant, waiting for an interrupt. It is
just waiting for a keypress or maybe the timer interrupt. The processor
never really turns completely off except when there are no batteries. I'm
pretty sure that it turns off the screen, disables the timer interrupt, and
then HALTs. Then it has extremely low power consumption until you press ON,
which causes and interrupt, and it starts the processing right back where it
left off. Hope that helps! (If I'm wrong about any of this, correct me :)
Ben
shakal@ns.net
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