Release 4 Compatibility - Revision history

Steven Solie: /* Exec */

2015-10-02T18:36:37Z

Exec

← Older revision		Revision as of 18:36, 2 October 2015
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	=== Exec ===		=== Exec ===

	* When an Exec device gets an IORequest, it must validate io_Command. If the io_Command is 0 or out of range, the device must return IOERR_NOCMD and take no other action. The ~~filesystem~~ now sends new commands and expects older devices to properly ignore them.		* When an Exec device gets an IORequest, it must validate io_Command. If the io_Command is 0 or out of range, the device must return IOERR_NOCMD and take no other action. The file system now sends new commands and expects older devices to properly ignore them.

	=== DOS ===		=== DOS ===

Daniel Jedlicka at 06:40, 9 September 2012

2012-09-09T06:40:01Z

← Older revision		Revision as of 06:40, 9 September 2012
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	* Depending on unsupported side effects or undocumented behavior. Be sure to read the Autodocs, include file comments and other documentation.		* Depending on unsupported side effects or undocumented behavior. Be sure to read the Autodocs, include file comments and other documentation.
	* Assuming current choices, configurations or initial values. If the current possibilities are A, B, or C, do not assume C if it isn't A or B. Check specifically for the choices currently implemented, and provide default behavior for unexpected values.		* Assuming current choices, configurations or initial values. If the current possibilities are A, B, or C, do not assume C if it isn't A or B. Check specifically for the choices currently implemented, and provide default behavior for unexpected values.
	* Amiga debugging tools such as ''MemGuard'' can find many program bugs that may affect compatibility. A program that is ''MemGuard'' clean stands a much better chance of working well under current and future versions of the OS.		Amiga debugging tools such as ''MemGuard'' can find many program bugs that may affect compatibility. A program that is ''MemGuard'' clean stands a much better chance of working well under current and future versions of the OS.

	== Release 4 Changes That Can Affect Compatibility ==		== Release 4 Changes That Can Affect Compatibility ==

Steven Solie at 15:49, 6 September 2012

2012-09-06T15:49:15Z

← Older revision		Revision as of 15:49, 6 September 2012
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	{{NeedUpdate}}
	== Release 4 Compatibility ==		== Release 4 Compatibility ==

Steven Solie at 15:48, 6 September 2012

2012-09-06T15:48:50Z

Show changes

Steven Solie at 22:55, 5 September 2012

2012-09-05T22:55:42Z

@@ Line 28: / Line 28: @@
 * Process structure is bigger. "Rolling your own" Process structure from a Task fails. Use dos.library System() or NewCreateProc().
 * Unless documented otherwise, you must be a process to call DOS functions. DOS function dependence on special process structures can change with OS revisions.
 === Timer Device ===
 === Intuition ===
 <li><p>You can‚Äôt type control characters into string gadgets by default. Use Ctrl-Amiga-char to type them in or use IControl Prefs to change the default behavior.</p></li>
 <li><p>Width and Height parameters of AutoRequest are ignored.</p></li>
@@ Line 90: / Line 56: @@
 <li><p>Window borders are now drawn in the screen‚Äôs DetailPen and BlockPen rather than the Window‚Äôs pens. For best appearance, you should pass an SA_Pens array to OpenScreen(). This can be done in a backwards compatible manner with the ExtNewScreen structure and the NS_EXTENDED flag.</p></li>
 <li><p>The system now renders into the full width of window borders, although the widths themselves are unchanged. Window borders are filled upon activation and inactivation.</p></li>
-<li><p>Window border rendering has changed significantly for 2.0. Note that the border dimensions are unchanged from 1.x (Look at window-&gt;BorderLeft/Top/Width/Height if you don‚Äôt believe us!). If your gadget intersects the border area, although it may have looked OK under 1.3, a visual conflict may occur under 2.0. If Intuition notices a gadget which is substantially in the border but not declared as such, it treats it as though it were (this is called ‚Äúbordersniffing‚Äù). Never rely on Intuition to sniff these out for you; always declare them explicitly (see the Gadget Activation flags GACT_RIGHTBORDER, etc.). See ‚ÄúIntuition Gadgets and Window Borders‚Äù in the ‚ÄúAdditional Information‚Äù section below.</p></li></ul>
+<li><p>Window border rendering has changed significantly for 2.0. Note that the border dimensions are unchanged from 1.x (Look at window-&gt;BorderLeft/Top/Width/Height if you don‚Äôt believe us!). If your gadget intersects the border area, although it may have looked OK under 1.3, a visual conflict may occur under 2.0. If Intuition notices a gadget which is substantially in the border but not declared as such, it treats it as though it were (this is called ‚Äúbordersniffing‚Äù). Never rely on Intuition to sniff these out for you; always declare them explicitly (see the Gadget Activation flags GACT_RIGHTBORDER, etc.). See ‚ÄúIntuition Gadgets and Window Borders‚Äù in the ‚ÄúAdditional Information‚Äù section below.</p></li>
 === Preferences ===

Steven Solie: /* Expansion */

2012-09-05T22:52:20Z

Expansion

← Older revision		Revision as of 22:52, 5 September 2012
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	* When an Exec device gets an IORequest, it must validate io_Command. If the io_Command is 0 or out of range, the device must return IOERR_NOCMD and take no other action. The filesystem now sends new commands and expects older devices to properly ignore them.		* When an Exec device gets an IORequest, it must validate io_Command. If the io_Command is 0 or out of range, the device must return IOERR_NOCMD and take no other action. The filesystem now sends new commands and expects older devices to properly ignore them.

	=== Expansion ===

	* ExpansionBase is private - use FindConfigDev().
	* Memory from contiguous cards of the same memory type is automatically merged into one memory pool.

	=== DOS ===		=== DOS ===

Steven Solie: /* DOS */

2012-09-05T22:51:59Z

DOS

← Older revision		Revision as of 22:51, 5 September 2012
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	=== DOS ===		=== DOS ===

		⚫	* Process structure is bigger. "Rolling your own" Process structure from a Task fails. Use dos.library System() or NewCreateProc().
	* DOS is now written in C and assembler, not BCPL. The BCPL compiler artifact which caused D0 function results to also be in D1 is gone. System patches in Release 2 that return some DOS function results in both D0 and D1 are not guaranteed to remain in the next release. Fix your programs! Use ''Scratch'' to find these problems in your code.
	* DOS now has a real library base with normal LVO vectors.
	* Stack usage has all changed (variables, direction).
	* New packet and lock types. Make sure you are not passing stack garbage for the second argument to Lock().
⚫	* Process structure is bigger. ~~‚ÄúRolling~~ your ~~own‚Äù~~ Process structure from a Task fails. Use dos.library System() or NewCreateProc().
	* Unless documented otherwise, you must be a process to call DOS functions. DOS function dependence on special process structures can change with OS revisions.		* Unless documented otherwise, you must be a process to call DOS functions. DOS function dependence on special process structures can change with OS revisions.

Steven Solie: /* Exec */

2012-09-05T22:51:07Z

Exec

← Older revision		Revision as of 22:51, 5 September 2012
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	=== Exec ===		=== Exec ===

		⚫	* When an Exec device gets an IORequest, it must validate io_Command. If the io_Command is 0 or out of range, the device must return IOERR_NOCMD and take no other action. The filesystem now sends new commands and expects older devices to properly ignore them.
	<ul>
	<li><p>Do not jump to location $FC¬†0002 ‚Äì the start of the ROM under 1.3 ‚Äì as part of performing a system RESET. The 2.04 Kickstart ROM has a temporary compatibility hack called ‚ÄúKickety-Split‚Äù which is a redirecting jump at $FC¬†0002. This hack does not appear on the ''A3000'' ROM and due to space considerations will not appear on future machines.</p></li>
	<li><p>Everything has moved.</p></li>
	<li><p>The Supervisor stack is not in the same place as it was under 1.3. This has caused problems for some games that completely take over the Amiga. If your program goes into Supervisor mode, you must either respect allocated memory or provide your own Supervisor stack when taking over the machine.</p></li>
	<li><p>ExecBase</p>
	<p>is moved to expansion memory if possible. Before, ExecBase would only end up in one of two fixed locations. Now, ColdCapture may be called after expansion memory has been configured.</p></li>
	<li><p>Exception/Interrupt vectors may move. This means the ''68010'' and above Vector Base Register (VBR) may contain a non-zero value. Poking assumed low memory vector addresses may have no effect. You must read the VBR on ''68010'' and above to find the base.</p></li>
	<li><p>No longer tolerant of wild Forbid() counts. Under 1.3, sometimes this bug could go unnoticed. Make sure that all Forbid()s are matched with one and only one Permit()(and vice versa).</p></li>
⚫	~~<li><p>~~When an Exec device gets an IORequest, it must validate io_Command. If the io_Command is 0 or out of range, the device must return IOERR_NOCMD and take no other action. The filesystem now sends new commands and expects older devices to properly ignore them.~~</p></li>~~
	<li><p>A fix to task-switching in Release 2 allows a busy task to properly regain the processor after an interrupt until either its quantum (4 vertical blanks) is up or a higher priority task preempts it. This can dramatically change the behavior of multitask programs where one task busyloops while another same-priority task Wait()s. See ‚ÄúTask Switching‚Äù in the ‚ÄúAdditional Information‚Äù section below.</p></li></ul>

	=== Expansion ===		=== Expansion ===

Steven Solie: /* Expansion */

2012-09-05T22:48:56Z

Expansion

← Older revision		Revision as of 22:48, 5 September 2012
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	=== Expansion ===		=== Expansion ===

		⚫	* ExpansionBase is private - use FindConfigDev().
	<ul>
		⚫	* Memory from contiguous cards of the same memory type is automatically merged into one memory pool.
	<li><p>ExpansionBase</p>
⚫	~~<p>~~is private - use FindConfigDev().~~</p></li>~~
⚫	~~<li><p>~~Memory from contiguous cards of the same memory type is automatically merged into one memory pool.~~</p></li></ul>~~

	=== DOS ===		=== DOS ===

Steven Solie at 22:48, 5 September 2012

2012-09-05T22:48:08Z

← Older revision		Revision as of 22:48, 5 September 2012
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	{{NeedUpdate}}		{{NeedUpdate}}
	== Release 2 Compatibility ==		== Release 4 Compatibility ==

	If you are developing new software or updating older software, you need to avoid compatibility traps. This ~~comprehensive~~ list of Release 2 compatibility problem areas can help you avoid and diagnose compatibility problems ~~In addition, you should refer to the "Amiga Programming Guidelines" listed in Chapter 1~~.		If you are developing new software or updating older software, you need to avoid compatibility traps. This is a partial list of Release 4 compatibility problem areas can help you avoid and diagnose compatibility problems.

	== General Compatibility Problem Areas ==		== General Compatibility Problem Areas ==

	The following improper Amiga programming practices are likely to fail on new ~~ROMs~~ or hardware.		The following improper Amiga programming practices are likely to fail on new OS versions or hardware.

	* Requiring all free RAM.		* Requiring all free RAM.
	* Overwriting memory allocations. With 32-bit addresses, a 1-byte overwrite of a string array can wipe out the high byte of a pointer or stack return address~~. This bug could go unnoticed on a 24-bit address machine (e.g., ''A500'') but crash the system or cause other problems on an ''A3000''~~.		* Overwriting memory allocations. With 32-bit addresses, a 1-byte overwrite of a string array can wipe out the high byte of a pointer or stack return address.
	* Improper flags or garbage in system structures. A bit that means nothing under one OS may drastically change the behavior of a function in a newer version of the OS. Clear structures before using, and use correct flags.		* Improper flags or garbage in system structures. A bit that means nothing under one OS may drastically change the behavior of a function in a newer version of the OS. Clear structures before using, and use correct flags.
	* Misuse of function return values. Use function prototypes and read the Autodocs for the functions you are using. Some system functions return just success or failure, or nothing at all (void). In such cases, the value which the function happens to return must not be used except as it is documented.		* Misuse of function return values. Use function prototypes and read the Autodocs for the functions you are using. Some system functions return just success or failure, or nothing at all (void). In such cases, the value which the function happens to return must not be used except as it is documented.
	* Depending on unsupported side effects or undocumented behavior. Be sure to read the Autodocs, include file comments and other documentation.		* Depending on unsupported side effects or undocumented behavior. Be sure to read the Autodocs, include file comments and other documentation.
	* Assuming current choices, configurations or initial values. If the current possibilities are A, B, or C, do not assume C if it isn't A or B. Check specifically for the choices currently implemented, and provide default behavior for unexpected values.		* Assuming current choices, configurations or initial values. If the current possibilities are A, B, or C, do not assume C if it isn't A or B. Check specifically for the choices currently implemented, and provide default behavior for unexpected values.
	* Amiga debugging tools such as ''~~Enforcer'', ''Mungwall'' and ''Scratch~~'' can find many program bugs that may affect compatibility. A program that is ''~~Enforcer''/''Mungwall''/''Scratch~~'' clean stands a much better chance of working well under current and future versions of the OS.		* Amiga debugging tools such as ''MemGuard'' can find many program bugs that may affect compatibility. A program that is ''MemGuard'' clean stands a much better chance of working well under current and future versions of the OS.

	== Release 2 Changes That Can Affect Compatibility ==		== Release 4 Changes That Can Affect Compatibility ==

	There are several areas where ~~Relase~~ 2 OS changes and enhancements can cause compatibility problems for some software.		There are several areas where Release 4 OS changes and enhancements can cause compatibility problems for some software.

	=== Exec ===		=== Exec ===
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	<p>is private - use FindConfigDev().</p></li>		<p>is private - use FindConfigDev().</p></li>
	<li><p>Memory from contiguous cards of the same memory type is automatically merged into one memory pool.</p></li></ul>		<li><p>Memory from contiguous cards of the same memory type is automatically merged into one memory pool.</p></li></ul>

	=== Strap ===

	<ul>
	<li><p>romboot.library</p>
	<p>is gone.</p></li>
	<li><p>Audio.device cannot be OpenDevice()ed by a boot block program. See ‚ÄúAudio Device‚Äù below.</p></li>
	<li><p>Boot from other floppies (+5,-10,-20,-30) is possible.</p></li>
	<li><p>Undocumented system stack and register usage at Diag and Boot time have changed.</p></li></ul>

	=== DOS ===		=== DOS ===
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	* Buffer is freeable, so low memory open failure is possible.		* Buffer is freeable, so low memory open failure is possible.
	* Do not disable interrupts (any of them), then expect trackdisk to function while they are disabled.		* Do not disable interrupts (any of them), then expect trackdisk to function while they are disabled.

	=== CIA Timers ===

	* System use of CIA timers has changed. Don‚Äôt assume how they‚Äôre used.
	* Don‚Äôt depend on initial values of CIA registers.
	* Don‚Äôt mess with CIABase. Use cia.resource.
	* If your code requires hardware level CIA timers, allocate the timers using cia.resource AddICRVector()! This is very important. Operating system usage of the CIA timers has changed. The new 2.0 timer.device (‚ÄúJumpy the Magic Timer Device‚Äù) will try to jump to different CIAs so programs that properly allocate timers will have a better chance of getting what they want. If possible, be flexible and design your code to work with whatever timer you can successfully allocate.
	* OS usage of INT6 is increasing. Do not totally take over INT6, and do not terminate the server chain if an interrupt is not for you.

	=== Other Hardware Issues ===		=== Other Hardware Issues ===
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	=== Intuition Gadgets and Window Borders ===		=== Intuition Gadgets and Window Borders ===



	If 2.0 Intuition finds a gadget whose hit area (gadget Left/Top/ Width/Height) is substantially inside the border, it will be treated as though it was declared in the border. This is called ‚Äúbordersniffing‚Äù. Gadgets declared as being in the border or detected by Intuition as being in the border are refreshed each time after the border is refreshed, and thus aren‚Äôt clobbered.		If 2.0 Intuition finds a gadget whose hit area (gadget Left/Top/ Width/Height) is substantially inside the border, it will be treated as though it was declared in the border. This is called ‚Äúbordersniffing‚Äù. Gadgets declared as being in the border or detected by Intuition as being in the border are refreshed each time after the border is refreshed, and thus aren‚Äôt clobbered.
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	# You currently hold a lock on this screen (see LockPubScreen()).		# You currently hold a lock on this screen (see LockPubScreen()).

		⚫	IntuiText rendered into a window (either through PrintIText() or as a gadget‚Äôs GadgetText) defaults to the Window RastPort font, but can be overridden using its ITextFont field. Text rendered with the Text() function appears in the Window RastPort font.
	IntuiText

		⚫	The Window's RPort's font shown above is the initial font that Intuition sets for you in your window's RastPort. It is legal to change that subsequently with SetFont().
⚫	rendered into a window (either through PrintIText() or as a gadget‚Äôs GadgetText) defaults to the Window RastPort font, but can be overridden using its ITextFont field. Text rendered with the Text() function appears in the Window RastPort font.

⚫	The ~~Window‚Äôs~~ ~~RPort‚Äôs~~ font shown above is the initial font that Intuition sets for you in your ~~window‚Äôs~~ RastPort. It is legal to change that subsequently with SetFont().

	=== Workbench and Startup ===		=== Workbench and Startup ===

		⚫	Under 4.0, simply avoid any output from your "s:startup-sequence". If your program opens a screen it will be the first screen the user ever sees. Note that if EndCLI is ever hit, the screen will pop open.


	Under 1.3, the Workbench Screen and initial Shell (CLI) opened before the first line in ‚Äús:startup-sequence‚Äù. Some naughty programmers, in an attempt to recover memory, would search for the bitplane pointers and appropriate the memory for their own use. This behavior is unsafe.

	By default 2.0 opens the initial CLI on the first '''output''' from the ‚Äús:startup-sequence‚Äù. This allows screen modes and other parameters to be set before the user sees the screen. However, this broke so many programs that we put in the ‚Äúsilent-startup‚Äù hack. A disk installed with 1.3 install opens the screen as before. A disk installed under 2.0 opens silently. Never steal the Workbench bitplanes. You don‚Äôt know where they are, how big they are, what format they may be in, or even if they are allocated. Recovering the memory is a bit tricky.

⚫	Under 2.0, simply avoid any output from your ~~‚Äús~~:startup-~~sequence‚Äù~~. If your program opens a screen it will be the first screen the user ever sees. Note that if EndCLI is ever hit, the screen will pop open.

	Under 1.3, after EndCLI, use CloseWorkbench() to close the screen. This also works under 2.0. Loop on CloseWorkbench() with a delay between loops. Continue looping until CloseWorkbench() succeeds or too much time has passed. Note that a new program called ''EndRun'' is available for starting non-returning programs from the startup-sequence. ''EndRun'' will reduce memory fragmentation and will close Workbench if it is open. ''EndRun.lzh'' will be available in Commodore‚Äôs Amiga listings area on BIX.