Given that the API states you can allocate up to ~1TB of memory and 2^40 (5
bytes) is just over 1TB I'd say the 5 byte offset seems reasonable. The API
also states that these pointers are not tagged BTW.

I will continue to play with this as time allows, but I'm going to argue
that it should stay on midrange-l and not move to MI since there is nothing
MI about this. It's esoteric, granted, but it's pure RPGLE and API coding.


Walden H Leverich III
Tech Software
(516)627-3800 x11

-----Original Message-----
From: Leif Svalgaard []
Sent: Tuesday, December 18, 2001 14:36
Subject: Re: Teraspace memory allocation

From: Steve Richter <>

> A spcptr contains a 5 byte segment and a 3 byte offset.  The teraspace
> pointer is probably a 3 byte segment and a 5 byte offset with a high
> order bit in the segment portion telling the machine where the
> segment/offset division is. ( my  speculation ).

Investigating this would make a nice chapter in my eBook (I need to get back
to writing a few more chapters - gotta earn a living too and the day only
got 24 hours :).

AFAIK the division between segment and offset is completely arbitrary on the
PPC RISC machines. Segments are not mapped to memory in any special way, the
mapping is done on a page (4K) basis.

I hope that Walden would take some time to check this out. We could also
speculate together, but maybe we should move the discussion to the MI-list

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