QHow can I force text-page-two shadowing on the Apple II GS?
A Most uses for text-page-two shadowing come from older, 8-bit applications that use
text page two. On the Apple IIGS, a Monitor ROM routine at $F962 (TEXT2COPY)
toggles shadowing of text page two, through hardware on ROM 3 and through software
on older machines. (A heartbeat task copies the bank $00 screen to the bank $E1
screen for software shadowing.)
TEXT2COPY is only a toggle--it can't tell you the current state of shadowing. To see if
shadowing is currently enabled (the user may have enabled it manually with the
Alternate Display Mode desk accessory), try storing a character in the bank $00
text-page-two screen, waiting more than 1/60th of a second and seeing if the
character has been copied to bank $E1.
QSome of the toolbox calls I make crash when executed with GSBug active, but behave
normally when GSBug isn't present. How come?
A GSBug is intolerant of toolbox calls made in 8-bit mode. Although theApple IIGS
Toolbox Reference (pages 1-2) clearly states that all toolbox calls must be made in
full native mode, the current tool dispatcher protects you by beginning with a REP
#$30 instruction. GSBug does not. Be sure to make all toolbox calls in full native
mode.
QIf I try to select a file in an SFPutFile dialog box and the file already exists, clicking
Save produces no action if I've entered ProDOS 8 since rebooting. Why?
A The System Software 5.0.2 Resource Manager does not restart correctly on return
from ProDOS 8. It doesn't correctly add the system resource file into the search path.
When Standard File detects that you're trying to save over an existing file, it calls
ErrorWindow to display a dialog box with the warning, "That file already exists," and
the choice to replace or cancel. ErrorWindow fails because the system resource file is
not open and the AlertWindow template can't be loaded. Standard File treats an error in
the ErrorWindow call as if you'd clicked Cancel in the "That file already exists" dialog
box. The net effect is that nothing at all happens. This is corrected in System Software
5.0.3.
QWhy do Apple IIGS fonts look tall and skinny, as if they were made out of rubber and
stretched too far in one direction? They look OK when I print using the "vertical
condensed" option.
A Nearly all the Apple IIGS fonts were originally designed for other systems, usually
the Macintosh. Font definitions for the Apple II GS and other systems are nearly
identical. Macintosh pixels are square; the width-to-height ratio of a pixel is 1:1.
Apple II GS pixels are much taller than they are wide (the ratio for Apple II GS 640
mode is about 5:12). When a font designed for square pixels is displayed on a system
with pixels of a different shape, the characters look stretched. This is what happens
on the Apple IIGS.
Apple could have changed the font strike for a more pleasing look at Apple IIGS
resolutions, but for legal reasons such a change would require renaming the fonts.
Times wouldn't be Times anymore, Helvetica wouldn't be Helvetica, and so on. The
fonts would look the same, but the names would have to be different. In the tradeoff
between appearance and well recognized font names, Apple chose to keep the familiar
names and font strikes. To compensate for the stretched fonts, all of Apple's printer
drivers include a "vertically condensed" printer option. Selecting this option causes
the printer drivers to print with double the screen's vertical resolution. Doubling the
vertical resolution effectively makes the pixel aspect ratio about 10:12, or 5:6,
which is close enough to square that the fonts look the way we expect them to.
Some fonts are designed for the Apple II GS aspect ratio of 5:12. Such fonts are
identified in their font family numbers by having the high bit set.
These questions and answers are compiled by the Apple II Developer Technical
Support group. *