🚀 go-pugleaf

On 2018-08-15 16:14, Charlie Gibbs wrote:
> On 2018-08-14, Johnny Billquist <b...@softjar.se> wrote:
> 
>> On 2018-08-14 03:38, Charlie Gibbs wrote:
>>
>>> The other machine that stands out in my mind is the PDP-11.  I once
>>> hand-disassembled the Dungeon machine code and was stunned by its
>>> elegance.  Making R7 the program counter and R6 the stack pointer,
>>> plus predecrement and postincrement, made it possible to do all sorts
>>> of nifty program control stuff with what at first looked like ordinary
>>> data manipulation instructions.  The Dungeon binary was threaded code
>>> implemented in hardware.
>>
>> You do know that Dungeon is written in FORTRAN? So you were
>> disassembling something produced by a compiler.
> 
> Yes, but all I had at the time was a copy of the binary.  I actually
> managed to write a program on a Univac 90/30 (an IBM 360 work-alike
> which I had much more ready access to) that emulated PDP-11 machine
> instructions, but the project foundered on the system calls, for
> which I had no documentation.

I can see that would be a bit trickier...

> A couple of years later I did get my hands on the source code -
> all 14,000 lines of FORTRAN - and ported it.  The hard part was
> the terminal I/O - going from character-mode asynchronous terminals
> to block-mode synchronous ones took some work.  But I had already
> done that for Adventure, so all I had to worry about were things
> like translating the ASCII files (including encrypted ones) to
> EBCDIC, writing functions for the bitwise logical operators which
> Univac FORTRAN didn't support, and replacing all the RAD50 constants
> with normal character constants.  But at least I finally got to play
> Dungeon right to the end.

That's what I call dedicated. :-)

   Johnny

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