Gnat Ada 9X - What sort of PC does it need???

Gnat Ada 9X - What sort of PC does it need???

[Michael Coburn]

Hi all,

I need a reliable indication of what sort of system requirements the
Gnat (PC) version of Ada9X imposes. I would also like to know at what
point more memory is needed. That is, when the size and complexity of
a program warrants > 4 meg of memory.
  
I am mainly concerned with programs written at undergraduate level - 
not major software projects.

I also need an indication of the processor, and speed requirements.

Thanks in advance...

 
--
|/-\| Michael Coburn              email: s9409498@yallara.cs.rmit.oz.au |/-\|
|\-/|                Two's Complement - Three's a crowd.                |\-/|

Re: Gnat Ada 9X - What sort of PC does it need???

[Robert Dewar]

Small programs can be compiled and run successfully in 4 megs of memory
if the OS environment is compatible with such a small memory size. Using
DJPP or Warp (i.e. OS/2 version 3.0, or the current Warp Beta), you can
probably manage fine with 4 megs. Of course these are virtual memory
systems, so memory is jut an aspect of performance, not capacity. Large
programs will begin to thrash the disk badly, but for example you may
still find that a 90MHz Penitum with 4 megs (what a horrible thought!)
out performs a 16 MHz 386 with 8 megs on a large program. You really have
to try yourself to see what performance you get and whether it is acceptable
to you.

Certainly we strongly recommend getting more memory, a reasonable lower
limit would be 8 megs for DJPP or OS/2, 12 megs for Linux, and 20 megs
for NT (when that GNAT port comes out, or perhaps less for Daytona).
Remember these days 4 megs of memory costs $150, and there is no better
investment you can make for improving performance of a PC for running 
large 32-bit applications (such as GNAT or the 32-bit OS environments
that support it!)

Re: Gnat Ada 9X - What sort of PC does it need???

[Robert Dewar]

Here is a more general idea of what hardware we recommend for running
the PC version of GNAT, using either OS/2 or DJPP:

Minimum:
  486 25 MHz
  200 meg hard drive
  8 megs of memory

such systems should be available with 14" color monitor in the $1250 range
or even cheaper if you settle for a no-name clone (but be sure to check
OS compatibility in this case, make sure you have a money back guarantee)
The $1250 is for a minstream machine (e.g. Compaq Presario 433, which is
actually a 33MHz machine, in fact you may as well go for a 33 MHz, really
they cost so little more today). Note that SZ or DX does not really affect
GNAT performance, since the compiler itself does not use floating-point.

Desirable:
  Pentium
  400 meg drive
  16 megs of memory

now you are in the $2000-$2500 range, although in the latest computer
shopper, there was a Pentium clone for less than $1500.

One of the nice things about the timing of GNAT is that the hardware that
you buy today has caught up nicely with the requirements of GCC/GNAT. A
couple of years ago, specs like the above would have seemed much too
luxurious, but these days, minimal student machines are likely to at
least match the "minimum" spec above (with the possible need to add
4 megs of memory).

Of course when compiling large programs or systems, more power will never
hurt. In particular, more memory is always helpful, and GNAT should be
able to take convenient advantage of the new symmetric multi processing
systems coming out (running OS/2 MP or NT with the soon to be available
GNAT port to NT/x86). THe lack of a required order of compilation is
particularly helpful when compiling large programs on an MP system.

Re: Gnat Ada 9X - What sort of PC does it need???

[Tom Griest]

In article <36os50$22j@gnat.cs.nyu.edu> dewar@cs.nyu.edu (Robert Dewar) writes:
[snip]

>Certainly we strongly recommend getting more memory, a reasonable lower
>limit would be 8 megs for DJPP or OS/2, 12 megs for Linux, and 20 megs
>for NT (when that GNAT port comes out, or perhaps less for Daytona).

Actually, 16MB seems to work pretty well on vanilla NT.  Of course,
our dual-processor 90MHz Pentium (Pent-house) system w/32MB running Daytona
does tend to make a 66MHz 486 w/16MB look a little slow. :-)

>Remember these days 4 megs of memory costs $150, and there is no better
>investment you can make for improving performance of a PC for running 
>large 32-bit applications (such as GNAT or the 32-bit OS environments
>that support it!)
>

I agree.  But two things you might want to keep in mind:

  1) Windows95 should be able to support gnat with 8MB.  If you are
     planning for a buy in early part of next year, this is a consideration.

  2) Memory prices seem to have stabilized, but there is a transition
     from 9-bit simms to 18-bit  (72-pin) simms underway.  If you sink
     a lot of money into 9-bit simms for a 486, you may not be able to 
     "take it with you" when you upgrade to a new 586 motherboard.


-Tom

Re: Gnat Ada 9X - What sort of PC does it need???

[tmoran]

The Gnat naming conventions (at least for the OS/2 version I have)
also imply two things: 1) an HPFS partition either on a new hard
disk or a repartitioning of an existing one; 2) if your editor only
understands 8.3 file names you'll need to switch to a new editor.

Re: Gnat Ada 9X - What sort of PC does it need???

[Robert Dewar]

If you are restricted to 8+3 file names (either because you are using DOS,
or using OS/2 on a FAT partition, or -- most aggravating of all if you ask
me -- you insist on using a junk editor that does not handle long file names)

you are not completely stuck
instead you can use the -gnatk8 switch when you compile, which uses a
crunching algorithm to crunch file names down to the 8+3 limit. The
associated gnatk8 utility that is part of the GNAT system can be used
to find the crunched name for a unit (although it is quite a simple
algorithm, see source of krunch.adb, and after a while easy to do in
your head).

Of course this does not guarantee uniqueness, and so you might have to
juggle unit names a bit, but in practice it works pretty well, and you
may well find you don't have any name clashes.

of course the other possibility, suitable for educational use, and actually
a convention we follow in GNAT itself, is simply to keep unit names short.
That's not so terrible:

if you use "use" clauses, then you don't often mention unit names anyway,
only in with clauses, so keeping them short does not have a big readability
effect.

if you don't use "use" clauses, then often people resort to doing local
renamings using abbreviated unit names because they can't stand giant
names before the dots. By keeping unit names short, you can use the real
unit names in qualification, which is often clearer.

Anyway, there are two ways of dealing with the "problem" that are a little
less drastic than repartioning the disk or switching editors.

My personal advice if you are using OS/2: probably worth taking the plunge.
Repartition and setup a big HPFS partition, and learn a new editor (I find
epm very nice, but also consider learning EMACS).

Re: Gnat Ada 9X - What sort of PC does it need???

[tmoran]

So I didn't need to buy a new hard disk and install HPFS?!  Arghh.
Somehow I missed seeing the gnatk8 stuff.  I'll go search now.
Is there also a utility to read arbitrarily named files and
rename them (to either HPFS or 8.3 names)? I have quite a bit
of old Ada 9X (and 83) source I'd be curious to try with GNAT.
>insist on using a junk editor that does not handle long file names
It is in fact an excellent editor - but it runs under DOS and does
not handle long file names.  If you think arguments over languages
are religious wars, just disparage a programmer's favorite editor
and find out what a *real* religious war is like.  -.-

Re: Gnat Ada 9X - What sort of PC does it need???

[Jean-Pierre Rosen]

> In article <36os50$22j@gnat.cs.nyu.edu> dewar@cs.nyu.edu (Robert Dewar) writes:
> [snip]
> 
> >Certainly we strongly recommend getting more memory, a reasonable lower
> >limit would be 8 megs for DJPP or OS/2, 12 megs for Linux, and 20 megs
> >for NT (when that GNAT port comes out, or perhaps less for Daytona).
FYI, I have installed GNAT on my portable (486/25, 4Megs, 84Megs Hard disk
with doublespace). It could be insufficient to compile large programs, but
it definitely allows me to practice 9X while on the plane :-)
Especially regarding disk space: I didn't install the whole of DJGPP, but
with the minimum required to run GNAT, I have enough space left for other
programs (Turbo Pascal, AmiPro and Freelance Graphics f.e., if you don't
install all the useless features that come with them ;-) ).

Re: Gnat Ada 9X - What sort of PC does it need???

[Robert Dewar]

Incidentally, I made a casual remark about EMACS which awakened at least
one VI disciple. To make it clear that I am not guilty of religeous
discrimination, let me rush to point out that there is also a VI for
OS/2 that works fine, and handles long file names.

Yes, there is a utility that renames files, and, optionally do the
8+3 krunching. It is called gnatchop, and is, even in our rather
incomplete documentation, reasonably fully described :-)