[fpc-devel] Re: Statistics on compiling the Free Pascal compiler for Win32

[Mark Morgan Lloyd]

Paul Robinson wrote:

 > I sometimes wonder if programmers at the Rite Aid or Walgreens drug
 > store chains use CVS.  (CVS is a competing drug-store chain in the US
 > as well as the name of a source-code repository system.)  Oh well, it
 > was a better joke when I thought of it.

I'd remind you that several other manufacturers (including Burroughs and 
ICL) used the IBM 029 card punch, even if they typically put their own 
logo on it.

 > On the pages on the Free Pascal Wiki I'm writing on my attempts to
 > port the Free Pascal Compiler over to the IBM 370 series machine
 > (known now as zSystem),

That seems an eminently good idea, since it's about the only major 
architecture (with the arguable exception of the Itanic) that FPC 
doesn't target.

 > with the initial target being an IBM 370 on OS/VS1,

Why not start with Linux? it's a bit more accessible for the rest of us, 
and you'll be able to refer to existing RTL source.

 > * It's Big Endian (I believe the PDP-11 minicomputer is also.)

As are SPARC and PPC, both of which FPC supports.

 > * The most you can access at any one point from a register is 4K,
 > whether that's a branch in code, or a piece of data. [...] Only
 > tables are available, in-line constants are generally not (this is
 > not exactly true, but is close)

I'd suggest reviewing the "Porting GCC to the IBM S/390 Platform" paper 
that I've cited on http://wiki.lazarus.freepascal.org/ZSeries, and 
selecting a base system that does allow inline constants. I think it's 
pretty unlikely that anything's left in (commercial) operation that's 
older than this, and the Hercules emulator (see for example 
http://wiki.lazarus.freepascal.org/Qemu_and_other_emulators#Debian_zSeries_Guest_using_Hercules) 
obviously supports the newer facilities.

 > * It's internal character set is EBCDIC, not ASCII.  Also, the
 > character set is not continuous along the alphabet, e.g. doing a test
 > on ['a'..'z'] or ['A'..'Z'] will fail because it will pick up other
 > non-alphabetic characters.

Again, I'd suggest starting off targeting hardware and OS that's happy 
with ASCII.

-- 
Mark Morgan Lloyd
markMLl .AT. telemetry.co .DOT. uk

[Opinions above are the author's, not those of his employers or colleagues]