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From: larry@JPL-VLSI.ARPA
Newsgroups: net.lang.ada
Subject: Ada on a PC
Message-ID: <8602070222.AA01241@ucbvax.berkeley.edu>
Date: Thu, 6-Feb-86 21:03:07 EST
Article-I.D.: ucbvax.8602070222.AA01241
Posted: Thu Feb  6 21:03:07 1986
Date-Received: Sun, 9-Feb-86 05:45:27 EST
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I received some material from Alsys today, including descriptions of their 
IBM PC/AT compiler.  The compiler looks very interesting; I intend to give 
it a close look at the SIGAda/AdaJUG meeting the last week of this month in 
L.A.  Alsys says they will be demoing their AT and their Sun versions at the 
very least.

The host is an AT with a hard disk, DOS 3.x, and at least 512K of memory.  
The compiler comes with a ~3 MB memory board that fits in a full slot.  You 
run under PC-DOS, using your own editor to create source files.  Source 
files are stored in a library created and maintained by an Alsys-proprietary 
library manager.  You could, of course, edit your files on an XT or any 
other system that creates ASCII files you could copy to your AT.  Possibly 
even the library manager would run on an XT or PC compatible.  Compilation, 
however, has to be done on the AT.

The Alsys linker binds into the load module a run-time executive which 
handles memory allocation/freeing.  It also implements tasking.  The 
resulting module will run on a PC or compatible under MS-DOS 2.x.  If you 
want to do any floating point the target must also have an 8087/80287 chip.
No mention is made of a symbolic debugger of any kind, a serious lack if 
there really is none.

If the target is an AT with more than 640K of memory you can have it run in 
virtual mode (this is NOT virtual memory, but the 16 MByte direct memory 
addressing feature of the 80286).  There's no need to recompile to have your 
program run in real or virtual mode; I assume this is a linker option.

Alsys claims the object code is about as compact and fast as C code.  The 
size of the run-time executive isn't given, however.  My guess is that the 
executable is probably a good deal bulkier than the C executable, primarily 
due to the tasking code.  (The dynamic-memory management should be comparable 
to the C code.)

Alsys says they'll soon pre-validate the AT compiler system under ACVC 1.6;
I suppose that means they'll eventually really validate it.  They say the 
total cost including the ~3MB memory should be under $3000.  If the compile 
and execution speed and load-module size isn't too bad, we'll probably buy a 
copy.  That combined with their CAI "Lessons on Ada" ought to make a good 
educational tool here at JPL.  Maybe we'll have deep-space craft someday with 
Ada code in them after all!
					Larry @ JPL-VLSI.arpa