[net.micro.6809] OS9 Level II program size

ingoldsby@calgary.UUCP (07/09/86)

I have a question for the OS9 gurus out there: How does OS9 Level II
cope with the 64K address space limit of the 6809?  I know that it
functions on systems with well over 64K, but can individual programs
be larger than 64K.  While I'm on the subject of OS9, does OS9/68K
also use position independent code for its modules?

		Terry Ingoldsby

dibble@rochester.UUCP (07/13/86)

> How does OS9 Level II
> cope with the 64K address space limit of the 6809?  
>  but can individual programs
> be larger than 64K.  While I'm on the subject of OS9, does OS9/68K
> also use position independent code for its modules?
> 
> 		Terry Ingoldsby

OS-9 Level Two uses a DAT (Dynamic Address  Translator) to map the 64K
address space of the 6809 into whatever memory the system has.  Each 
_task_ can see one 64K address space at a time.  Modules can be in any
number of address spaces at the same time.  There are lots of tricks for 
using more than 64K at a time.  All the tricks turn on splitting the program
into several tasks, each with up to 64K, or swapping pages between address
spaces.

OS9/68K requires position independent code.

Peter Dibble