[fpc-pascal] How are Assigned, Free, Nil and Destroy related?

Mark Morgan Lloyd markMLl.fpc-pascal at telemetry.co.uk
Mon Oct 24 08:27:00 CEST 2011

Ralf A. Quint wrote:
> At 11:52 AM 10/23/2011, Frank Peelo wrote:
>> If I recall corerctly, that Modula-2 value for nil was the address the 
>> 8086 jumped to when released from RESET. So jumping through a pointer 
>> with value nil would be something you would notice pretty much 
>> immediately.
> Certainly not. Modula-2 was/is not depending on any CPU specifics, 
> certainly not on anything x86, considering that the first computers 
> Modula-2 ran on were the Xerox Alto and the Lilith, using M-Code, and 
> both not even a remote connection to anything x86. And a lot of 
> non-Wirth Modula-2 implementation ran on Motorola 68k before I can 
> remember to have seen the first x86 implementation (not sure if it was 
> FST or XDS)...

We're getting off-topic. I *DID* specify that it was one, particular 
compiler that had that behaviour: if I recall correctly it was the first 
version that Logitech targeted at OS/2 (the one that bombed when you 
said BYTE(0)). I've also seen ffff:0000 used by a disassembler 
(Sourcer), possibly for the same value that Frank suggests.

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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