Re: A92: Backup files
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Re: A92: Backup files
> So it is possible to change the vectors at the begin of the RAM. But the
> Fargo backups are only 39KB big. So how can be modified vectors? Such a
> backup file is too small, isn' t it ? Can you explain that or can you send
> me a descripe me how can I change vectors or how can I execute assembly
> commands. I'm very interested
> in Fargo and I use it as my new operating system. So I want to get answers
> of my questions.
The new fargo backups use a 'callback' function built into the TI-OS. The
one David uses is an event-callback, that is, after the backup is sent the
TI-OS goes back to looking for user input and notices that the callback address
is filled out. After recieving an event (such as an idle event), the TI-OS
calls the callback function to do some filtering. This callback installs
Fargo. You can see all this when you examine the backup with a hex editor.
Also, you can dissassemble the TI-ROM looking for low-memory addresses. This
is probably how David found the event-callback in the first place.
--Bryan
bcturner@eos.ncsu.edu
References: