December 94 - LETTERS
PENMODE NOT FOR TEXT
In the Macintosh Q & A section of develop Issue 18, I noticed the suggestion to use PenMode(srcBic)
for drawing white text on a black background. This is wrong; the desired result will be achieved by
TextMode(srcBic). Hope this helps.
-- David Surovell
Thanks for the correction. Say, don't I recognize your name from an article in Issue 19? -- Caroline Rose
SLIME: IS IT SAFE?
As I was reading develop Issue 18, I came across the green slime question in Macintosh Q & A. A
friend of mine has been looking for just this recipe, to help keep her preschool-aged daughter
amused. However, after reading the recipe, I'm not going to forward it to my friend, because one of
the ingredients, borax, is poisonous.
Now, I'm not a toxicologist, nor do I play one on TV, so I don't know exactly how toxic borax is.
But I don't want to find out by letting anyone's children play with it (not even the nasty little feral
children down the street). And what about people who screw up the recipe? Or decide to experiment
with it? You didn't even tell them that straight borax is poisonous. And it's not like there's a big
"Mr. Yuk" sticker on the box of Twenty-Mule Team, just those friendly-looking equines.
You and your staff do a fine job of technical presentation, and you have a process for technical
review. You might consider a "toxicity review" before you publish any more recipes for nifty stuff
that's not inherently edible. Ya never know.
-- Greg Guerin
I volunteer at the Exploratorium, a science museum in San Francisco, and we've been handing out this slime
for months to any kid who wants it. The recipe was acquired from a grade-school teacher and is used in schools
all over the country.
A chemist at the Exploratorium told me that borax is toxic to about the same degree as soap: if you eat enough
of it, you'll probably get a belly ache. Any kid who's old enough to have figured out that soap is yucky to eat is
plenty old enough, in my opinion. It's my sincere hope and belief that most develop readers have already
reached that stage of maturity.
To be absolutely sure, I called the Poison Control center, and they said that to have any toxic effect at all
someone would have to eat an awful lot of it. They even told me I didn't need to bother to wash my hands after
handling it. I asked if the soap analogy was a good one, and they said it was accurate.
You might recommend corn starch and
cold water to your friend. In the right proportions (just enough water to get it all wet) it makes a very
satisfying goop (usually called "oobleck" by teachers, after Dr. Seuss) that's probably more appropriate for very
-- Dave Johnson
DOGCOW IN THINK REFERENCE
I really enjoyed reading Mark Harlan's history of the dogcow in Issues 17 and 18 of develop . He
states that Technical Note #31 has not been available for quite a while. That may be so, but
something like this Tech Note is hiding inside the THINK Reference databases. Just do a search for
"DogCow" and you'll find it.
-- Robert Grimm
Thanks for pointing out the dogcow lore in THINK Reference; I didn't know about that. I especially like the
part about how, since the dogcow is two-dimensional, she can face a predator head-on to avoid being seen.
Although that defensive maneuver sounds likely enough, keep in mind that the dogcow information in
THINK Reference is unauthorized and has nothing to do with the Tech Note. The Tech Note gives lots more
information, and we're glad it remains as mysterious as ever.
-- Caroline Rose
PUZZLING OVER THE PUZZLE PAGE
After reading Issue 17 of develop , I have a question. I'm not sure what the purpose is in calling KON
& BAL's page a Puzzle Page if it requires that you have access to certain obscure beta ROMs in
order to solve the puzzle. Perhaps this is just sour grapes because I've never scored above 5? Sure, it
still demonstrates various debugging techniques (although I'm not sure that iterative debugging with
a reboot after each test is a very useful technique, and this seems quite common in the puzzle pages).
But is it really a puzzle?
-- Peter Lewis
KON & BAL chose the Puzzle Page format because they thought it was a fun way to give people debugging
tips. They don't expect readers to take the puzzle aspect of it seriously; in fact, you're the first one we've ever
heard from who has scored anything besides 0.
None of us were thrilled with Issue 17's puzzle, but, in KON's words, "There was a lot of great stuff about
how the Resource Manager works, locking down handles, and
other really useful advice. We try to demonstrate efficient and good debugging techniques."
Want a better Puzzle Page? Why not write one yourself? We now accept "guest puzzlers," as you may have
noticed. If you've got a good idea for a Puzzle Page, please send it to us at AppleLink DEVELOP.
-- Caroline Rose
SAVED BY THE PUZZLE PAGE
I've enjoyed reading develop since the first issue was published.
I find that the articles contain a lot of
useful technical information.
Normally I try to read each issue when it arrives, but when Issue 16 arrived, it sat for two months
while I was finishing a product. About two weeks after the application shipped, a bug was reported
where the application would randomly crash with a trashed stack on the PowerBook 180c. We spent
a very frustrating Friday trying to reproduce and isolate the bug, but the behavior was inconsistent.
Over the weekend, in an effort to catch up on my reading, I picked up develop Issue 16 and read
through it. About
an hour after I finished, I thought back on KON & BAL's Puzzle Page, picked the magazine up
again, and reread it. Something struck me about the problem they were puzzling over. Their result
sounded similar to the problem we were encountering.
On Monday, we ran a series of tests in which we were able to prove that the bug was in Sound
Manager 2.0 and disappeared under Sound Manager 3.0. If it hadn't been for the timely coincidence
of reading develop and seeing a different manifestation of our bug described, we might have spent a
lot longer tracking down the problem. develop saved us a lot of time and frustration.
Thanks for the magazine.
-- Bruce D. Rosenblum
IT PAINS US WHEN YOU DON'T WRITE We welcome timely letters to the editors, especially from
readers reacting to articles that we publish in develop . Letters
should be addressed to Caroline Rose (or, if technical develop -related questions, to Dave Johnson) at Apple Computer,
Inc., One Infinite Loop, M/S 303-4DP, Cupertino, CA 95014 (AppleLink CROSE or JOHNSON.DK). All letters should
include your name and company name as well as your address and phone number. Letters may be excerpted or edited for
clarity (or to make them say what we wish they did). *