[HECnet] MACRO-11 cross assembler for VMS

[Johnny Billquist]

On 2020-03-07 02:12, Robert Armstrong wrote:
>>Didn't early Vaxen (11/780) also execute PDP-11 code?
> 
>    Yes, you are correct that the hardware could do it but to actually 
> run PDP-11 programs you needed a layered software product for VMS called 
> the RSXAME (“Application Migration Executive”).  The AME came with 
> MACRO11, task builder, and a bunch of other stuff.

Unless I remember wrong, initially AME wasn't that much of a product, 
but a part of VMS itself. Early versions of VMS was pretty much mostly 
RSX userland, with only a few VMS specific components. Over time this 
changed, obviously.

>    I don’t have it, though, and I haven’t seen a copy since the early 
> 1980s.  I’m not even sure it would work on a MicroVAX, either.  Only the 
> VAX-7xx models and (I think) the 8600 actually had compatibility mode; 
> it got dropped from the architecture pretty fast after that.  I seem to 
> remember that DEC added a software emulation feature for later VAXes 
> that didn’t have compatibility mode, but I don’t remember the details.

As VAXen stopped including PDP-11 compatibility, AME became more of an 
actual product which was separate. This then also included emulating the 
whole PDP-11 instruction set on machines that didn't the compatibility 
mode. So by this time, installing AME was possible on any VAX.

And yes, only the VAX-11 machines had PDP-11 compatibility mode in 
hardware (and I still kindof think of the 8600 as the VAX-11/790, which 
was the original designation for it). No machines after the 86x0 have 
the compatibility mode in hardware. And no micro-VAX ever had it.

AME was definitely a product still in the 90s. I think it got retired 
along with the VAX itself. AME is (obviously) not available on Alpha or 
anything newer.

One thing I'm sortof curious about is if a VAX-11 could run an RSX 
program even without AME. Actually, maybe I should just try, since I do 
have the way of testing that... But it might be that even the system 
calls were diked out of VMS and placed in AME at some point, along with 
the handling of switching in and out of PDP-11 mode.

>    In any case I don’t really need all that – I just want to assemble 
> some stand alone PDP-11 programs that I can then download to a real -11.

I think using a PDP-11 is easier than getting AME.

   Johnny

-- 
Johnny Billquist                  || "I'm on a bus
                                   ||  on a psychedelic trip
email: bqt at softjar.se             ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol