TweetFollow Us on Twitter

Winter 92 - APPLE II Q & A

APPLE II Q & A

APPLE II Developer Technical Support

Q What's the best way to do text-only printing to a character device through GS/OS? 

A If you want to print text to a GS/OS character device, here's how you do it:

  1. Look at all the on-line devices to find which are character devices. You can tell when a device is a character device by examining bit 7 of the "characteristics" word returned by DInfo--the bit is set for block devices and clear for character devices. You don't have to hard-code a list of character device IDs.
  2. Present the user with a list of device names followed by their location and generic type in parentheses. You can adjust the names of device types to reflect your use. For example, ".RPM (AppleTalk printer, port 1)," ".DEV2 (serial modem, port 2)," or ".DEV3 (generic character device, slot 5)." You can use bit 3 of the slot returned by DInfo to know whether to return "slot" or "port," too.
  3. When the user selects a printing device, call Open on the device name (such as .RPM for an AppleTalk printer). Use Write to write the information, just as you would to a file; then call Close (you can call Flush if you like, but it shouldn't be necessary). That's all you need to do.

Remember not to embed ImageWriter or any other printer-specific codes in the output stream. With the exception of choosing a device and creating a file, this same code could be used to print to any  text printer or to another device such as a disk or modem. You might give users a "text printing preferences" dialog where they can enter some codes if they like, and you might have built-in sets for ImageWriters and other common printers, but don't make it too complicated. These instructions are very generic and will work well on any setup, not just an ImageWriter II connected through the serial port.

Q On a ROM 03 Apple II GS, I save and restore the mouse mode by getting it from ReadMouse, setting the mode to what I need, and restoring the value (with SetMouse) when done. This sometimes kills the mouse--I don't get any mouse movement until my program quits. Help! By the way, this isn't a problem on ROM 01 machines.  

A The ROM 03 mouse firmware doesn't behave as documented in two respects. First, it sometimes returns an illegal mouse mode value from ReadMouse. Specifically, there's garbage in the high nibble of the mouse mode byte. Second, SetMouse returns an error and takes no action when passed an invalid mode, even though the Apple IIGS Toolbox Reference  says it returns no errors. When you try to restore the invalid mode, nothing happens and the mouse stays in whatever mode you had it in--if it's not what the system needs, the mouse will appear "hung" until someone sets the mode to what the system does need.

You can work around this problem by masking off the high nibble of the mode result from ReadMouse (AND #$000F in 65816 assembly) before passing it to SetMouse. This problem is fixed in Apple IIGS system software version 6.0-- ReadMouse always returns a valid mode under 6.0.

Q When I call SFMultiGet2, I randomly get error $1705 (bad pathname descriptor in the reply record) even though that error doesn't mean anything for that call. Any ideas? 

A All versions of SFMultiGet2 before Apple II GS System 6.0 incorrectly look at two of the words in the reply record (offsets $0008 and $000E) to make sure they don't contain the value $0002. That value would be illegal in those positions--in any of the other  new Standard File calls. SFMultiGet2 doesn't use the same reply record, but pre-6.0 versions of Standard File accidentally check those fields anyway. Make sure the values in bytes that are past the beginning of the 6-byte reply record are not $0002. This is fixed in System 6.0.

Q Although my application fully supports GS/OS, the Finder uses slashes instead of colons in the pathnames in message #1. This means my application can't open any files that have slashes in the filename. 

A The Finder and its message-passing conventions were originally released before GS/OS was written. Applications depend on the slash (/) as the separator character to be able to parse these pathnames (for example, to find the filename to use in a document window title). If the separator character were to change, many older applications would break.

Finder version 6.0 may support an additional message containing a list of fully expanded GS/OS pathnames. These pathnames use colons as separators and aren't limited to 255 characters. See the Finder 6.0 documentation for details on using this message.

Q I've written a program that hangs inside Standard File under Apple II GS System 5.0.4, but works fine under development versions of 6.0. I'm not using any 6.0-specific features. What could be the problem? 

A Standard File before System 6.0 does not behave gracefully if called with both prefix 0 and prefix 8 empty. Try setting one of these prefixes to an existing directory and see if your problem vanishes.

Q I can't find the ProDOS partition on Volume IX or later of the Developer CD Series discs. What's happened? 

A Apple II information was duplicated on all Developer CDs from Volume III through Volume VIII because without the ProDOS partition, Apple II users couldn't see the information, and without the Apple II folder on the HFS partition, the information couldn't be shared on an AppleShare file server (or Macintosh System 7 File Sharing). Apple II GS System 6.0 includes an HFS (Macintosh) file system translator, which means that Apple II GS developers can access the information on the HFS partition, making the ProDOS partition unnecessary.

The Apple II information can be found on the HFS partition with the pathname Dev.CD Vol. IX:Development Platforms (Moof!):Apple II. Note that this means the Apple II folder can only be accessed from ProDOS 8 using AppleShare with long naming on--the path to the Apple II folder is not a legal ProDOS 8 pathname.

Q Apple II Applesoft's floating-point routine results are sometimes accurate to only two places. For example, the answer returned for PRINT 55555.099-55555.09 is 9.01031494 E-03. How can we get more accurate results? 

A The accuracy loss you're experiencing with the Applesoft floating-point routines is normal. If you convert a number such as 55555.099 to a base 2 floating-point number, you won't get an exact representation using Applesoft's floating-point routines or even 96-bit precision IEEE numerics. Because 9.01031494 E-03 is 0.0090103, you can see that you have accuracy out to three and a half decimal places. The solution is to determine the accuracy that you want and massage the result to give you that accuracy. Here's a sample program that shows common Applesoft rounding techniques:

1 REM Round to 3 decimal places of accuracy example
10 Input a
20 Input b
30 If a-b>1000 then 100: REM no 3-digit rounding of numbers >1000
40 Print "Standard Applesoft Non-accurate result:";a-b
50 Print "Truncated result:";
   INT((a-b)*1000)/1000 60 Print "Rounded result:";
   INT(((a-b)+.0001)*1000)/1000
70 Goto 10
100 Print "Result has 3 decimal accuracy already:";a-b
110 Goto 10

This is the only way that you can get Applesoft to clip the numbers, apart from using a separate floating-point engine. Alternatively, you can do your own conversion from Applesoft internal numeric format to a string in assembly language and have it simulate the above operation when converting the number.


Kudos to our readers who care enough to ask us terrific and well thought-out questions. The answers are supplied by our teams of technical gurus; our thanks to all. Special thanks to Matt Deatherage, Jim Luther, Dave Lyons, Jim Mensch, and Tim Swihart for the material in this Q & A column. *



Have more questions? Need more answers? Take a look at the Dev Tech Answers library on AppleLink (updated weekly) or at the Q & A stack on the Developer CD Series  disc.*

 
AAPL
$524.94
Apple Inc.
+5.93
MSFT
$40.01
Microsoft Corpora
-0.39
GOOG
$536.10
Google Inc.
-20.44

MacTech Search:
Community Search:

Software Updates via MacUpdate

Mac DVDRipper Pro 4.1.7 - Copy, backup,...
Mac DVDRipper Pro is the DVD backup solution that lets you protect your DVDs from scratches, save your batteries by reading your movies from your hard disk, manage your collection with just a few... Read more
PDFpenPro 6.2 - Advanced PDF toolkit for...
PDFpenPro allows users to edit PDF's easily. Add text, images and signatures. Fill out PDF forms. Merge or split PDF documents. Reorder and delete pages. Even correct text and edit graphics! Create... Read more
PDFpen 6.2 - Edit and annotate PDFs with...
PDFpen allows users to easily edit PDF's. Add text, images and signatures. Fill out PDF forms. Merge or split PDF documents. Reorder and delete pages. Even correct text and edit graphics! Features... Read more
Monolingual 1.5.9 - Remove unwanted OS X...
Monolingual is a program for removing unnecesary language resources from OS X, in order to reclaim several hundred megabytes of disk space. It requires a 64-bit capable Intel-based Mac and at least... Read more
Maya 2015 - Professional 3D modeling and...
Maya is an award-winning software and powerful, integrated 3D modeling, animation, visual effects, and rendering solution. Because Maya is based on an open architecture, all your work can be scripted... Read more
Starcraft II: Wings of Liberty 1.1.1.180...
Download the patch by launching the Starcraft II game and downloading it through the Battle.net connection within the app. Starcraft II: Wings of Liberty is a strategy game played in real-time. You... Read more
Sibelius 7.5.0 - Music notation solution...
Sibelius is the world's best-selling music notation software for Mac. It is as intuitive to use as a pen, yet so powerful that it does most things in less than the blink of an eye. The demo includes... Read more
Typinator 5.9 - Speedy and reliable text...
Typinator turbo-charges your typing productivity. Type a little. Typinator does the rest. We've all faced projects that require repetitive typing tasks. With Typinator, you can store commonly used... Read more
MYStuff Pro 2.0.16 - Create inventories...
MYStuff Pro is the most flexible way to create detail-rich inventories for your home or small business. Add items to MYStuff by dragging and dropping existing information, uploading new images, or... Read more
TurboTax 2013.r17.002 - Manage your 2013...
TurboTax guides you through your tax return step by step, does all the calculations, and checks your return for errors and overlooked deductions. It lets you file your return electronically to get... Read more

Latest Forum Discussions

See All

Where's My Water? Featuring XYY (G...
Where's My Water? Featuring XYY 1.0 Device: iOS Universal Category: Games Price: $.99, Version: 1.0 (iTunes) Description: iPod Touch 4th Gen, iPhone 3GS or iPad 1 are not compatible with this app. | Read more »
The Amazing Spider-Man 2 (Games)
The Amazing Spider-Man 2 1.0.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0.0 (iTunes) Description: *IMPORTANT* The Amazing Spider-Man 2 requires an iPad 2 (or newer), iPhone 4s (or newer), or iPod touch 5th... | Read more »
Living Planet - Tiny Planet Videos and P...
Living Planet - Tiny Planet Videos and Photos 1.0 Device: iOS Universal Category: Photography Price: $.99, Version: 1.0 (iTunes) Description: 50% OFF LAUNCH SPECIAL! BUY NOW BEFORE THE PRICE GOES UP... | Read more »
Livescribe 3 Smartpen Review
Made by: Livescribe Price: $149.99 for Livescribe 3 Hardware/iOS Integration Rating: 4.5 out of 5 stars Usability Rating: 4 out of 5 stars Reuse Value Rating: 4.75 out of 5 stars Build Quality Rating: 4.5 out of 5 stars Overall Rating: 4.44 out of... | Read more »
Unpossible Review
Unpossible Review By Carter Dotson on April 17th, 2014 Our Rating: :: RALPH WIGGUM APPROVESUniversal App - Designed for iPhone and iPad Unpossible is much better than its English!   | Read more »
Hitman GO Review
Hitman GO Review By Carter Dotson on April 17th, 2014 Our Rating: :: GO HITMAN, GO!Universal App - Designed for iPhone and iPad Hitman GO is not the obvious way to do a mobile version of the Hitman series, but it’s an incredibly... | Read more »
Monster High Ghouls and Jewels is a Frea...
Monster High Ghouls and Jewels is a Freaky Fashion-Forward Match-3 Puzzler Posted by Rob Rich on April 17th, 2014 [ permalink ] | Read more »
Dinosaur Train A to Z Review
Dinosaur Train A to Z Review By Amy Solomon on April 17th, 2014 Our Rating: :: DINO DETAILSUniversal App - Designed for iPhone and iPad Dinosaur Train A to Z is an educational app about dinosaurs that includes In-App Purchases... | Read more »
Easter Comes to Junk Jack X – Bringing N...
Easter Comes to Junk Jack X – Bringing New Crafts, Chemistry, and More Posted by Rob Rich on April 17th, 2014 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »
Call of Cookie Review
Call of Cookie Review By Jordan Minor on April 17th, 2014 Our Rating: :: COOKIE CRUMBLESUniversal App - Designed for iPhone and iPad Call of Cookie proves that plants aren’t the only fighting foods out there.   | Read more »

Price Scanner via MacPrices.net

Apple restocks refurbished Mac minis starting...
The Apple Store has restocked Apple Certified Refurbished Mac minis for up to $150 off the cost of new models. Apple’s one-year warranty is included with each mini, and shipping is free: - 2.5GHz Mac... Read more
Hyundai Brings Apple CarPlay To The 2015 Sona...
Hyundai Motor America has announced it will bring Apple CarPlay functionality to the 2015 Sonata. CarPlay is pitched as a smarter, safer and easier way to use iPhone in the car and gives iPhone users... Read more
Updated iPads Coming Sooner Than We Had Thoug...
MacRumors, cites KGI securities analyst Ming Chi Kuo, well-respected as an Apple product prognisticator, saying that Apple will introduce an upgraded iPad Air and iPad mini in 2014/Q3, meaning the... Read more
Toshiba Unveils New High And Low End Laptop M...
Toshiba has announced new laptop models covering both the high-end and low-end of the notebook computer spectrum. Toshiba 4K Ultra HD Laptop Toshiba’s new Satellite P55t features one of the world’s... Read more
Save up to $270 with Apple refurbished 13-inc...
The Apple Store has Apple Certified Refurbished October 2013 13″ Retina MacBook Pros available starting at $1099, with models up to $270 off MSRP. Apple’s one-year warranty is standard, and shipping... Read more
Apple now offering refurbished iPad mini with...
The Apple Store has Certified Refurbished 2nd generation iPad minis with Retina Displays now available starting at $339. Apple’s one-year warranty is included with each model, and shipping is free.... Read more
Microsoft Blinks – Drops Microsoft Office 365...
Microsoft has dropped the annual subscription fee for Microsoft Office 365 Personal – which is needed in order to create and edit documents in Microsoft Office for iPad. However, Apple’s iOS and OS X... Read more
New AVG Vault Apps for iOS and Android Help K...
AVG Technologies N.V. an online security company for 177 million active users, has announced the launch of its latest mobile application, AVG Vault. The free app introduces an innovative user... Read more
Free Local Carrot iPhone App Helps Find Fresh...
I love fresh vegetables. I’m not a vegan, although I was for several years in the 1980s, but fresh vegetables and other whole foods are still my dietary mainstays as a matter of taste rather than... Read more
CarSO Pro – Car Service and Finance Manager/O...
Lviv, Ukraine-based BM-Studios’ CarSO Pro is a tool to manage operations concerning your car. Never forget to change the oil or prolong the insurance for your car. Remember when you’ve done the car... Read more

Jobs Board

*Apple* Solutions Consultant (ASC) - Apple (...
**Job Summary** The ASC is an Apple employee who serves as an Apple brand ambassador and influencer in a Reseller's store. The ASC's role is to grow Apple Read more
*Apple* Retail - Manager - Holyoke - Apple I...
Job Summary Keeping an Apple Store thriving requires a diverse set of leadership skills, and as a Manager, you’re a master of them all. In the store’s fast-paced, Read more
*Apple* Retail - Manager - Apple (United Sta...
Job SummaryKeeping an Apple Store thriving requires a diverse set of leadership skills, and as a Manager, you're a master of them all. In the store's fast-paced, dynamic Read more
*Apple* Solutions Consultant (ASC) - Apple (...
**Job Summary** The ASC is an Apple employee who serves as an Apple brand ambassador and influencer in a Reseller's store. The ASC's role is to grow Apple Read more
*Apple* Retail - Market Leader - Cincinnati...
…challenges of developing individuals, building teams, and affecting growth across Apple Stores. You demonstrate successful leadership ability - focusing on excellence Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.