On Wed, 14 Aug 2002, Eric Smith wrote:
> Note that neither manual explicitly discusses the concept of having
> multiple windows on the screen simultaneously, although the first
> paragraph in the newer manual suggests that when it proposes using
> the feature to "protect areas of the screen from being overwritten with
> new text." The earliest game program I wrote for the Apple ][ (in
> Integer BASIC), back in late 1977, took advantage of this feature to
> display multiple windows for different aspects of the game, and even
> used inverse-video space characters to create visible borders for
> the windows. The utility of multiple independent text windows was
> readily apparent to even a novice programmer. Since the Apple monitor
> would only keep track of one window and cursor location, it fell upon
> the application programmer to track multiple sets and swap the relevant
> values in and out of the zero page variables used by the monitor
> ($20-23 for window bounds, 24-25 for cursor location, and 28-29 for
> current line base address (or call VTAB at FC22 after switching)).
By gum, you're right. I remember becoming cognizant of the possibilities
and experimenting with this myself.
> As anyone who used the Apple ][ extensively will tell you, many programs
> did use multiple windows, although only a few programs presented
> overlapping windows. Most were tiled, but at least a few allowed
> overlap in a limited manner. The most common form of overlap that I
> recall seeing in Apple II programs was the creation of a new window
> overlapping existing information in order to prompt the user for some
> input, akin to a "dialog box" in modern GUIs.
Yeah, but I don't remember any of those being prior to 1983. Maybe you
do, but my experience with the Apple ][ started in late 1983.
Sellam Ismail Vintage Computer Festival
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Received on Wed Aug 14 2002 - 05:58:00 BST