Re: [Amforth] External Interrupt Mask Register

[Matthias T. <mt...@we...>]

Hi,

> When I do the command $1d c@ . I get a value of 0001000. How is that
> possible? Or do I something wrong?

Historically Atmel defined 32 special addresses 
that together with
certain opcodes that are used for
some IO or CPU relevant things (e.g.
the machine
status register which is one of them). They are mapped 
into
the "normal" memory addresses with an offset 
of 32 (0x20). "real" RAM
memory starts at address
$40 (32 registers and 32 IO registers).

The lowest 32 "memory" addresses are used for the 
CPU registers itself. $1d is part of the Y register 
pair amforth uses as data stack pointer.

HTH
Matthias