Path: utzoo!attcan!uunet!lll-winken!xanth!ukma!tut.cis.ohio-state.edu!ucbvax!LUCID.COM!lnz
From: lnz@LUCID.COM (Leonard N. Zubkoff)
Newsgroups: comp.sys.apollo
Subject: Re:  Parallel port drives user nuts
Message-ID: <8903190753.AA00485@atlantis>
Date: 19 Mar 89 07:53:55 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 12

In answer to (5) on the line_width value returned by gpr_$inq_bitmap_pointer:

GPR bitmaps are not necessarily organized such that the pixels of one line
are immediately followed by the pixels of the next line in memory.  Consider
direct mode access to a window that is not the full screen width, for example.

So the pixels on one line are found from the storage_ptr value, and the pixels
of the next line are found by adding 2*line_width to the original pointer,
and so on.  As documented in the insert file, the line width is the number
of 16bit words per line, which is the reason for multiplying by 2.

		Leonard