TweetFollow Us on Twitter

Apr 97 Tips

Volume Number: 13 (1997)
Issue Number: 4
Column Tag: Tips & Tidbits

Tips & Tidbits

By Steve Sisak

Debugging 68K Code Resources with MacsBug

I'm using a CDEF as an example here, but this technique can be quite useful in many situations.

I recently had the pleasure of writing a tiny application for an old client. There was actually more code in the custom CDEF than the app itself. Once it was all polished and "bug free" I took it to the client's site for a demo. Naturally, it crashed immediately on launch. Everything froze up and I had to do a hard reset. I strongly suspected my CDEF was the problem. Normally, I would put a DebugStr in the CDEF, recompile, and use MacsBug to find the problem. But this was a 4MB LCII. There was no chance of installing CodeWarrior and rebuilding the CDEF. However, the computer did have an old copy of ResEdit. The following is what I did.

1) I opened my application in ResEdit and used the GetInfo dialog to make my CDEF preloaded and locked. I then saved the file and quit ResEdit.

2) In MacsBug, I set an A-trap break on InitGraf.

atb _InitGraf

3) I launched my app. Since initializing QuickDraw is one of the first things my program does, my A-trap break fired and I dropped into MacsBug.

4) The MacOS automatically loads preloaded resources when the resource file is open, so I found my CDEF in memory and set a breakpoint. To find the resource, I typed "hd RS" (list all resources in the current heap).

The screen looked something like this

hd RS

Displaying the "Quick Launch" heap at 00192830

Start Length Tag Mstr Ptr Lock Prg Type ID

00194890 00000544 R 00192A00 L CODE 0001

00196872 00000A44 R 00192A04 L CDEF 0080


5) Since my CDEF was already loaded in memory, and locked down, I set a breakpoint at the beginning of the CDEF.

br 00196872

I then typed command-g to continue. My breakpoint was soon hit and the bug identified. I fixed the problem the next day and got paid. This technique can be used to set a breakpoint at the beginning of nearly any code resource.

Damon Cokenias

In the MacTech 13.02 (February 1997) we printed a tip from Bill Hayden that System 7.5.3 made it possible to navigate the Standard File dialog box by clicking items visible on the desktop. Since then, a number of readers have written to report they could not reproduce this behavior.

After trying a variety of system software releases, we have not found a publicly released version of the system exhibiting this behavior, although one reader has reported reproducing it on a version of System 7.5.3 release 2 but not 7.5.5.

We offer two possible explanations for the source of the tip. First is a freeware utility called "Click, there it is!", by Richard Cardona Utilities Group (now in version 1.0.7), which enables the behavior described in the tip. A second possible explanation is that the reported functionality may have been enabled in a developer release of system software, but removed from the final, public release.

In any case, we apologize for the error and thank everyone who took the time to report it, as well as those who have taken the time to submit tips - please keep them coming.

Best wishes,



Community Search:
MacTech Search:

Software Updates via MacUpdate

Square Rave guide - How to grab those te...
Square Rave is an awesome little music-oriented puzzle game that smacks of games like Lumines, but with its own unique sense of gameplay. To help wrap your head around the game, keep the following tips and tricks in mind. [Read more] | Read more »
Snowboard Party 2 (Games)
Snowboard Party 2 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: Crowned the best snowboarding game available on the market, Snowboard Party is back to fulfill all your adrenaline needs in... | Read more »
The best games like Animal Crossing on m...
Animal Crossing amiibo Festival is out right now for the Wii U, reminding us of just how much fun that world can be. Or at least to go back and check in on our villages once in a while. [Read more] | Read more »
Between 2 Taps - Tap for Tap interview M...
Hello, and welcome back to Between 2 Taps, Tap for Tap’s Indie Dev interview series. [Read more] | Read more »
Facility 47 (Games)
Facility 47 1.0.1 Device: iOS Universal Category: Games Price: $3.99, Version: 1.0.1 (iTunes) Description: You wake up alone and freezing in an icy cell. You try the cell door but it’s locked, it seems that you are stuck with no... | Read more »
The best Photoshop alternative on iPad
Instagram and Lightroom are great and all, but sometimes people need to get extra creative with their image editing.Like, Photoshop creative. If you're one of these people, take a look at our pick for the best mobile Photoshop experience on iPad... | Read more »
The Walking Dead: No Man’s Land guide -...
A new update for The Walking Dead: No Man’s Land was released last week, making it the perfect time for you to head back to your base and take out some walkers. Here’s the lowdown on what’s new to the game, and how to take advantage. [Read more] | Read more »
Goat Rider guide - Tips and tricks to st...
We've all been there. One second, we're riding high on a crazed goat, and the next, we've been tossed off it like someone who's no good at goat ridin'. [Read more] | Read more »
Real Boxing 2 CREED: How to become a gre...
Just in time for Rocky fans who can’t wait to see CREED, the latest movie, we have the official tie-in game,Real Boxing 2 CREED. It builds on the success of its predecessor and there’s lots to take in so we at 148apps thought we’d run you through... | Read more »
CoinOp Heroes 2 guide - How to build an...
CoinOp Heroes 2 justlaunched and, like all clickers, it's dangerously addictive stuff. You have to furiously tap your screen to defeat wave after wave of foes and earn an insane amount of cash to spend on character upgrades and an army of minions... | Read more »

Price Scanner via

Best Buy Black Friday deals: Up to $200 off M...
Best Buy has posted their Black Friday sale prices for 2015. Save on MacBook Pros, MacBooks, MacBook Airs, iMacs, iPads, and Apple Watches. Choose free shipping or free local store pickup (if... Read more
Save $30-$40 on new Apple TVs after rebate
Adorama has new Apple TVs on sale for up to $40 off MSRP after mail-in rebate, good through December 15th. Shipping is free, and Adorama charges NY & NJ sales tax only: - 32GB Apple TV: $119.99... Read more
13-Inch Haswell MacBook Air At Two Years – Th...
The 13-inch mid-2013 “Haswell” MacBook Air I ordered in Apple’s November 2013 Black Friday sale was my first new Mac in four and a half years — the longest interval I’ve gone between system upgrades... Read more
Target Black Friday Early Access deals: $100...
Target is offering early access to their Black Friday deals on Apple products on their online store for today, the 25th, only. Choose free shipping or free local store pickup (if available): - Apple... Read more
BlackBerry Q3 Mobility Index Report Finds iOS...
BlackBerry has announced results of its thirteenth Good Mobility Index Report, showing that organizations are increasingly building custom secure apps. Among Good Powered by BlackBerry (formerly Good... Read more
Wednesday roundup of early Black Friday Mac s...
Save up to $500 on a new Mac with these early Black Friday deals from Apple resellers, currently the lowest prices available for these models: (1) B&H Photo has all new Macs on sale for up to $... Read more
iPod nano on sale for $119, $30 off MSRP
Walmart has the 16GB iPod nano (various colors) on sale for $119.20 on their online store for a limited time. That’s $30 off MSRP. Choose free shipping or free local store pickup (if available). Sale... Read more
Adorama Black Friday deals: Up to $400 off Ma...
Adorama has released their Black Friday deals for 2015. Save up to $400 on MacBook Pros, $200 on MacBooks and MacBook Airs, and $270 on iMacs. Use code RYBFDEAL during checkout to see these prices.... Read more
B&H Photo Deals: $200 off 12-inch 1.2GHz...
In addition to the B&H Photo Black Friday week sales we posted yesterday, B&H has lowered their price on two products to $200 off MSRP: - 12″ 1.2GHz Gray Retina MacBook: $1399 save $200 - 13... Read more
Best Buy Early Access: Today only, Up to $125...
Best Buy has iPad Air 2s on sale for up to $125 off MSRP and Apple Watch models on sale on their online store for up to $100 off MSRP with special codes through midnight CT tonight. Choose free... Read more

Jobs Board

Hardware Systems Integration Engineer - *App...
# Hardware Systems Integration Engineer - Apple Watch Job Number: 39380139 Santa Clara Valley, Califo ia, United States Posted: Apr. 23, 2015 Weekly Hours: **Job Read more
Sr. Technical/Project Manager, *Apple* Educ...
# Sr. Technical/Project Manager, Apple Education Job Number: 36588557 New York City, New York, United States Posted: Jul. 30, 2015 Weekly Hours: 40.00 **Job Summary** Read more
*Apple* Retail - Multiple Positions (US) - A...
Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, you're also the Read more
Merchant Operations Manager: *Apple* Pay -...
Changing the world is all in a day's work at Apple . If you love innovation, here's your chance to make a career of it. You'll work hard. But the job comes with more than Read more
*Apple* Pay QA Manager - Apple Inc. (United...
Changing the world is all in a day's work at Apple . If you love innovation, here's your chance to make a career of it. You'll work hard. But the job comes with more than Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.