WHDLoad
WHDLoad is a software package for the Amiga platform to simplify the installation of software on a hard drive , e.g. B. for demos or games . It enables better compatibility for Amiga software, which, due to the very different hardware specifications of the Amiga product line in the course of its history, can sometimes have hardware incompatibilities that make it difficult to use in emulated environments. WHDLoad basically bypasses the operating system in the Amiga for more compatibility and preserves the original program environment.
The tool enables an installed floppy image to be started automatically by clicking on an icon.
Two special parts are required, each of which was written specifically for the client program: To install a medium, it must be read from the original diskette and written to an image file on the hard disk by the "Imager" . Then the installed program can be started from a virtual drive with the "slave" interface.
Slave interface
The "slave" interface enables interaction between the program and WHDLoad and coordinates reading and writing of files. This makes it possible to run or emulate programs that are incompatible with conventional emulators such as WinFellow or WinUAE . WHDLoad can simplify the use, since the work to find out the exact configuration in the emulators mentioned above is no longer necessary.
history
The main reason for this loader is that a large number of computer games for the Amiga do not interact properly with the AmigaOS operating system, run directly on the Amiga hardware and make specific assumptions about registers , storage locations, etc. The hardware of the newer Amiga models has been heavily reworked, so that these assumptions failed when trying to run the same games on newer hardware and vice versa with newer games on older hardware. WHDLoad offers a possibility to install such games on an AmigaOS-compatible hard drive and to run them on newer hardware. Another advantage is the avoidance of loading times and disk changes, since everything that the game needs is saved on the hard drive. Also, floppy disks degrade faster than hard drives, so installing games with WHDLoad helps keep the games going.
WHDLoad was released on September 5th, 1996, the latest version 18.3 is from April 2017.
properties
WHDLoad takes over the entire operating system, which can lead to problems with some software (e.g. TCP / IP stack ), but exiting the game or the demo returns the system to its normal operating state.
WHDLoad games are stored on the AmigaOS file system as disk images , with driver files known as "WHDLoad slaves" being used. These slave files are freely available on the Internet (as freeware ), but the games themselves must be purchased separately to prevent software piracy . In addition, many fans have made their own freeware games available, which are also free and legal.
A special feature of the WHDLoad drivers is that they also remove old password queries in games for which code lists or the original manuals had to be kept ready at that time. Some WHDLoad drivers also remove real bugs in games or add new features, such as: B. a switch for PAL / NTSC 50 / 60Hz, or a support of the second joystick button, z. B. in Battle Squadron.
functionality
The WHDLoad "slave" interface is integrated in the operating system. The program can be executed at any time by double-clicking on a program symbol. When the user executes the program, the AmigaOS operating system loads the executable WHDLoad file and starts it. The loader then checks the software and hardware environment, loads and checks the slave interface required for the selected demo or game and allocates the required memory to the installed program. If the function 'Preload' is activated on the request side of WHDLoad, the program tries to load disk images and files into the main memory (if free space is available).
At this point, WHDLoad performs its main task of switching off the AmigaOS operating system, deactivating multitasking and interrupts , and copies memory areas that are used by AmigaOS and required by the installed program to an unused space until the AmigaOS is needed again.
WHDLoad also degrades the graphics hardware to OCS on original Amiga computers (this function can actually also work on emulated Amigas, but only in the newer versions of WinUAE that recognize WHDLoad and keep its interrupts), then WHDLoad initializes all hardware with defined values and jumps to the slave interface required for the respective program.
The slave interface loads the main program executable of the installed program by calling a WHDLoad function ( resload_DiskLoad or resload_LoadFile ), then patches the main program (so that the loaded program is able to load its data saved via the slave onto the hard disk, to fix compatibility problems and to allow an exit from the program) and calls the main program.
At this point the program that was installed can do the job it was written for and load its data as if it were from a real floppy disk.
The user can interrupt the execution of the loaded program with a "Quit" key (usually F10). When this action is performed, the slave interface returns to WHDLoad by calling an internal function resload_Abort .
The operating system is restored with all hardware registers and the original display. The memory and all allocated resources remain free for further use.
conditions
A standard Amiga 1200 or Amiga 600 without additional memory only works with a limited number of games. That usually means games with OCS / ECS and a floppy disk . It is recommended that either a 4 MB - or 8 MB to install RAM extension in the trapdoor slot to be compatible for 99% to ensure the Games.
A hard drive is required, the number of games that can be installed depends on their size.
Footnotes
- ↑ Drummond, Richard (May 2000). "AFCD52, Retro Gaming". Amiga format. No. 136. Future Publishing. p. 69. ISSN 0957-4867.
- ↑ Kasík, Pavel (October 1998). "WHDLOAD V7.0". Amiga Review (in Czech). No. 37. Atlantida Publishing. p. 25. ISSN 1211-1465.
- ↑ Topolnicky, Peter (September 2006). "WHDLoad". Amiga Future (in German). No. 62. APC & TCP. p. 29
- ↑ Topolnicky, Peter (November 2006). "Workshop: WHDLoad". Amiga Future (in German). No. 63. APC & TCP. pp. 40-41
- ↑ http://www.whdload.de/games/BattleSquadron.html