🚀 go-pugleaf

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.

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.

-- 
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