Stopping stuff

[JoeImp]

Ok, I have a question. Let's say you were linked to another calculator, and they were using an asm program to send stuff to you, just a sendbyte thing. Is there any way that I could have an asm program running that catches everything sent to my calculator and somehow doesnt use it, or get rid of it?

[Adm.Wiggin]

i don't know, i will leave this one up to either, Justin W., Jbirk, or David L.

[Adm.Wiggin]

I wouldn't know... That sounds like it would work though, the TI-OS is somehow able to know when a connection becomes active...

[NETWizz]

You can meake a getkeyhook because it is always active.

The hook would watch the link insertion bit of the correct port.

Upon cable entry, you need to put the calculator into IM 2 after setting your interrupt vectors, creating a table and code.

There is more

You cannot use jp $3a, jp $38, or do anthing that would run the IM 1 interrupt handler. You will use reti to run the IM 2 only.

Your IM 2 handler would need to be incredibly complicated because it would need to handle APD, the Keyboard, the Screen, and anything else IM 1 handles.

The only difference is that you would not have a Link Port Driver.

Upon removal of the link cable, your program should reinstate IM 1.

__________

Another option:

You could try wrighting a getkeyhook to continuously reset port 0 (hold a line lo).

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Yet another option:

Link Hook probably have to talk to Jason Kovas, Michael Vincent, or Dan Englender.

Suffice it to say, it is very difficult because TI-OS is handling the Link Port and likes to listen too it!

What are you trying to do? If you are trying to prevent calcs from sending programs to each other, I wrote an app for that

If you are trying to circumvent TestGuard, that would take a more complicated approach because you would have to make TI-OS unable to listen to the port.

[JoeImp]

Ok then, thsi might take a while, thx 4 ur help

[Adm.Wiggin]

u mean u couldn't just have an iterrupt that each time ran, reset the linkport to 0? then it could process main TI-OS interrupt, and it would read it as 0... i dunno, just a speculation...

[David]

If the calculator is using the silent link protocol, one could set a link hook that disables the silent link.
The specs are as follows:
In 83+ ROM versions 1.13 and above, there is a link hook. It is called upon the silent linking routine receiving a byte.

To enable: B_CALL 50CE
To disable: B_CALL 4F69

bit 7,(iy+36h) controls this hook. Memory address is 9BD0.

Inputs: None
Outputs: Z flag will cancel the silent link routine.

[NETWizz]

David,

Is it really that easy?

Just set the hook and have it set the Z flag?

cp a ;will set the Z flag.

[David]

Yes, according to the documentation, it is that easy.