🚀 go-pugleaf

In article <1989Dec19.161509.10803@mks.com>, andy@mks.com (Andy Toy) writes:
> Here's some more information that may be helpful that someone else
> here pointed out to me.
> --
> 2) The 20 file limit of the file descriptor table per process may be increased
>    by putting a different pointer into the PSP (currently there is a
>    seg:offset address inside the PSP to a 20 byte area in the PSP for
>    the file descriptor codes).  This can be pointed to any other location
>    and a new size given (e.g. 200 open files).  The limit is probably
>    255 because FF is reserved to mean that that entry is closed)

For my own interest, I looked up the PSP description in Thom Hogan's "The
Programmer's PC Sourcebook" and can add the following details:

(As of DOS3.3):
	PSP Offset 18H: Handle Table (20 bytes). Usual contents are FFH =
	slot available. One byte per handle, bit 7 = not inherited (I presume
	this means you can have 128 files inherited by child processes and
	127 files which aren't).

	PSP Offset 32H: Handle Table size (2 bytes). Usual contents are
	14H,00H.

	PSP Offset 34H: Handle Table address (if not at 12H - 4 bytes).
	Usual contents are 12H,00H,00H,00H (0000:0012H).

(Hope I have the byte orders correct.)
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