troubles with the timer value at $4ba

[vol]

I just want to read a timer value by

move.l $4ba,d0

and I get "Panic: bus error".  What is it?  Documentation shows that it is a long value.  What is wrong?  Please help me to read the timer.  Thank you.

Edited April 24, 2021 by vol

[vol]

Sorry I missed "The address range from 0 to $800 (2048) can be accessed only in the supervisor mode".  But is there a way to get a timer value from an application program?

It was unknown to me that the ST actually has an MMU which can protect some memory areas.  The Amiga doesn't have any such things despite having a multitasking OS.  It is an interesting discovery for me.

[vol]

Finally I has been able to find an answer to my question. It is here. 

Edited April 24, 2021 by vol

[ParanoidLittleMan]

10 hours ago, vol said:

Sorry I missed "The address range from 0 to $800 (2048) can be accessed only in the supervisor mode".  But is there a way to get a timer value from an application program?

It was unknown to me that the ST actually has an MMU which can protect some memory areas.  The Amiga doesn't have any such things despite having a multitasking OS.  It is an interesting discovery for me.

Sure, there is a way, supported by TOS. XBIOS function # 38 - subroutine execution in supervisor mode.