[fpc-devel] On a port of Free Pascal to the IBM 370

Mark Morgan Lloyd markMLl.fpc-devel at telemetry.co.uk
Thu Jan 19 13:00:06 CET 2012

Mark Morgan Lloyd wrote:
> Felipe Monteiro de Carvalho wrote:
>> 2012/1/18 Tomas Hajny <XHajT03 at hajny.biz>:
>>> As pointed out in my other e-mail, "everywhere necessary" implies either
>>> "dear user, convert all your files from the original encoding before you
>>> want programs created in FPC to touch them"
>> Yes, no problem here. I assume there must be some program in this
>> platform which can edit ASCII text and another one (or the same) to
>> convert text files between encodings. If not, just use the new port to
>> cross-compile such a program =)
> Just a moment. Granted that everybody's favourite reference site is 
> unavailable today, but minimal Googling suggests that MUSIC/SP- which I 
> believe was Paul's OS of choice- supports web browsing etc.
> I think we need a reality check from Paul here, in case EBCDIC operation 
> is mandated only by the emulator he was planning to use (whether I think 
> his choice is good is irrelevant- lets try to get things like character 
> set resolved before it causes any more sound and fury).

It appears that MUSIC/SP requires a particular hardware opcode (IUCV) to 
access TCP/IP, and that this is not provided directly by the Hercules 
emulator. IUCV can be provided by either IBM VM running between Hercules 
and a guest OS such as MUSIC/SP or Linux, or alternatively by running 
the Sim390 emulator instead of Hercules. For completeness, Linux gets 
around this by using SLIP to encapsulate IP rather than assuming that IP 
(and lower-level protocols) is handled by the hardware or host OS.

I see MUSIC/SP described as "unix-like", but I don't know whether it is 
sufficiently close to industry norms to run standard tools such as make, 
and even if the compiler is intended to be PC-hosted I think that would 
be unfortunate. MUSIC/SP running on Sim390 should have networking etc., 
but I for one have reservations about an initial port to an OS that 
might turn out to be significantly removed from POSIX etc. If I have 
time I might have a bit more info on this later, as well as on the 
character set issue.

One important point, and I don't much like raising this, is that it 
turns out that the principal maintainer of both MUSIC/SP (through his 
work at McGill) and Sim390 died in 2008. I agree with Paul that a 
mainframe port is worth attempting, but I've got reservations about his 
choice of target hardware and OS unless he can make a case that there is 
a significant number of S/370 and older (i.e. without inline operands) 
S/390 still in the field.

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

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

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