Re: A86: RST 10
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Re: A86: RST 10
At 04:13 PM 9/23/97 -0400, you wrote:
>In a message dated 97-09-23 15:19:40 EDT, you write:
>
>>
>> can someone tell me how to use RST commands and what exactly they're used
>> for? sorry this is proably basic stuff to ya'll. all i know about them is
>> that they're used to find things in memory right?
>>
>> thanx,
>> Patrick
>>
>>
>
>Restarts are used to call locations in ROM that are called commonly. RST 20h
>and RST 10h both deal with finding variables. I believe 00h has something to
>do with formatting the calc, or maybe a self test. Anyway, they go all the
>way from 00h to 40h in increments of 8h. (00h,08h,10h,18h, etc). I think
>they actually call that address in rom but are faster or more efficient or
>something. (someone correct me if I'm wrong) Once I get my Z80 books (if
>_ever_) then I can tell you more about it... :-(
>
>~Stephen Hicks
>
>
Yeah, you're exactly right. TI just put commonly used routines at those
entry points. The reason is because <rst 10h> is 2 bytes shorter than
<call $0010> and those bytes can add up.
RST $10 finds the variable whose id, length, and name are in op1
RST $20 puts the variable id, length, and name into op1
RST $00 does start the calc, because that is the initial code started when
calc is started. (actually only when batteries are taken out and back in)
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Alan Bailey mailto:bailela@charlie.cns.iit.edu
IRC:Abalone Web:http://www.iit.edu/~bailela/
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