[fpc-pascal] MS DOS 8086 compiler?

Mark Morgan Lloyd markMLl.fpc-pascal at telemetry.co.uk
Sun Apr 28 20:07:13 CEST 2013

Marco van de Voort wrote:
> In our previous episode, Mark Morgan Lloyd said:
>>> Actually, I have a vintage IBM PC 5150, with a 4.77 MHz 8088 processor, 
>>> so this isn't true, it's very testable actually :) However, the i8086 
>>> code generator still generates some 186/286+ instructions, so it doesn't 
>>> work there yet, but I'm planning to fix this shortly. Here's a video of 
>>> a few very simple Free Pascal compiled programs on a true 80186:
>> OK, answering my own question then. A pure-8086 port could be valuable 
>> if it generated reliable code for something like vtprolog.pas, since 
>> this implements its own garbage collection relying on detailed knowledge 
>> of how Turbo Pascal manages its heap.
> Heap management is mostly a RTL feature. For high TP compatibility, things
> like calling conventions must also match.

Yes, but in the specific case I gave the program extends the heap 
management. In practical terms it could be replaced with a mark/release 
arrangement, since when the program is trying to find a solution based 
on predefined rules it won't be extending them.

But as it stands it's a good test of TP-compatibility.

> IOW 8086 codegeneration is not automatically full TP compatibility on the
> binary level.

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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