Re: branch address architecture, not interactive use, The Design of Design

On Tue, 14 May 2024 02:59:38 -0000 (UTC)
John Levine <johnl@taugh.com> wrote:

According to MitchAlsup1 <mitchalsup@aol.com>:

   JSR PC,@(SP)+
>
Popped the return address off the stack, pushed another return
address on the stack and transfers control. This is how we did
coroutines. 

 
When I was teaching an operating system class in about 1977 I
challenged the class to come up with a minimal coroutine package. They
all found that pretty quickly.
 
It's not very good coroutines since it just switches the return
address, not any other stack context, but it can sometimes be useful.
 
 

I would guess that is was sometimes usefull in 1967, much less often
usefull 1977 and almost never useful (on "big" general-purpose
computers) in 1997 or later.