Re: A86: Re: system variables


[Prev][Next][Index][Thread]

Re: A86: Re: system variables




At 23:30 1998-11-23 -0500, you wrote:
>
>ComAsYuAre@aol.com wrote:
>
>> do you or anyone else know how addressing was done on the ti-85?  since
>> there's obviously no _asm_exec_ram, are the progs moved somewhere or
just run
>> from their original location? it musta been hard to do...
>
>Programs are run from wherever they happen to be in memory.  All call
>and jump address are given as offsets from the start of the program
>(.org 0) and then added onto the program's start address which is saved
>in memory whenever it's run.  This is how ZShell works anyway, I havn't
>looked into Usgard/Rigel/PhatOS yet.

ZShell adds the start address runtime which makes calls and jumps
(not relative) "slow". Usgard adds the start address at execution
time ("relocation" used in Fargo and other OS on the 89/92). Rigel
and PhatOS moves the program to a fixed location (right after
the shell). The two latter methods have both advantages and
disadvantages, while the ZShell method has no advantage whatsoever :)
--
Real name:     Jimmy Mårdell         
Email:         mailto:yarin@acc.umu.se
Homepage:      http://www.acc.umu.se/~yarin/

Icarus Productions homepage: http://icarus.ganymed.org/


References: