WHDLoad is a software package for the

Amiga Amiga is a family of personal computers introduced by Commodore in 1985. The original model is one of a number of mid-1980s computers with 16- or 32-bit processors, 256 KB or more of RAM, mouse-based GUIs, and significantly improved graphi ...

platform to make installation of software to a

hard disk A hard disk drive (HDD), hard disk, hard drive, or fixed disk is an electro-mechanical data storage device that stores and retrieves digital data using magnetic storage with one or more rigid rapidly rotating platters coated with magnet ...

easier, for such things as

demos Demos may refer to: Computing * DEMOS, a Soviet Unix-like operating system * DEMOS (ISP), the first internet service provider in the USSR * Demos Commander, an Orthodox File Manager for Unix-like systems * plural for Demo (computer programming) ...

games A game is a structured form of play, usually undertaken for entertainment or fun, and sometimes used as an educational tool. Many games are also considered to be work (such as professional players of spectator sports or games) or art (such ...

. Allowing for better

compatibility Compatibility may refer to: Computing * Backward compatibility, in which newer devices can understand data generated by older devices * Compatibility card, an expansion card for hardware emulation of another device * Compatibility layer, compon ...

for Amiga software, which can sometimes have hardware incompatibilities making them hard to use in

emulated In computing, an emulator is Computer hardware, hardware or software that enables one computer system (called the ''host'') to behave like another computer system (called the ''guest''). An emulator typically enables the host system to run so ...

environments due to the widely varying hardware specifications of the Amiga product line across its history. WHDLoad basically circumvents the operating system in the Amiga for greater compatibility and preserves the original program environment. WHDLoad makes it possible to autostart an installed

floppy disk A floppy disk or floppy diskette (casually referred to as a floppy, or a diskette) is an obsolescent type of disk storage composed of a thin and flexible disk of a magnetic storage medium in a square or nearly square plastic enclosure lined w ...

image by clicking an icon. Two special parts are required, each one specially written for the client program: To install media, it must be read from the original disk and written to an image file on the

hard drive A hard disk drive (HDD), hard disk, hard drive, or fixed disk is an electro-mechanical data storage device that stores and retrieves digital data using magnetic storage with one or more rigid rapidly rotating platters coated with magnet ...

by the "Imager". Then the installed program can be run from a virtual disk drive with the "Slave" interface.

Slave interface

The "Slave" interface allows interaction between the program and WHDLoad, and co-ordinates the reading and writing of files. This makes it possible to run or emulate programs that are traditionally incompatible with common emulators such as WinFellow, or

WinUAE UAE is a computer emulator which emulates the hardware of Commodore International's Amiga range of computers. Released under the GNU General Public License, UAE is free software. History Bernd Schmidt conceived of an emulator that can run Ami ...

. WHDLoad can be easier to use than trying to figure out the exact configuration for the aforementioned emulators as well.

History

The primary reason for this loader is that a large number of

computer game Video games, also known as computer games, are electronic games that involves interaction with a user interface or input device such as a joystick, game controller, controller, computer keyboard, keyboard, or motion sensing device to gener ...

s for the Amiga don't properly interact with the AmigaOS operating system, but instead run directly on the Amiga hardware, making assumptions about specific control registers, memory locations, etc. The hardware of newer Amiga models had been greatly revised, causing these assumptions to break when trying to run the same games on newer hardware, and vice versa with newer games on older hardware. WHDLoad provides a way to install such games on an AmigaOS-compatible hard drive and run on newer hardware. An added benefit is the avoidance of loading times and disk swaps, because everything the game needs is stored on the hard drive. The first public release of WHDLoad was on September 5, 1996, and the latest available version is 18.8 released in May 2022.

Features

WHDLoad takes over the entire operating system which may cause problems with some software (e.g. TCP/IP stack), but quitting the game or demo restores the system back into its normal working state. WHDLoad games are stored on the AmigaOS file system as

disk image A disk image, in computing, is a computer file containing the contents and structure of a disk volume or of an entire data storage device, such as a hard disk drive, tape drive, floppy disk, optical disc, or USB flash drive. A disk image is us ...

s, relying on driver files known as "WHDLoad slaves" to work. These slave files are freely available from the

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(as

Freeware Freeware is software, most often proprietary, that is distributed at no monetary cost to the end user. There is no agreed-upon set of rights, license, or EULA that defines ''freeware'' unambiguously; every publisher defines its own rules for the f ...

), but the games themselves have to be acquired separately, to prevent

software piracy Copyright infringement (at times referred to as piracy) is the use of works protected by copyright without permission for a usage where such permission is required, thereby infringing certain exclusive rights granted to the copyright holder, su ...

. Additionally, many fans have made their own freeware games, which are also freely, and legally, available.

How WHDLoad works

The WHDLoad "Slave" interface is integrated into the OS in such way that one can double-click a program icon to run the program at any time. When the user executes the program, by clicking a stored image icon, the AmigaOS operating system loads the WHDLoad executable and starts it. Then the loader checks the software and hardware environment, loads and checks the Slave interface required for that chosen demo or game and allocates required memory for the installed program. If the ''Preload'' feature is enabled into the requester page of WHDLoad, then the program attempts to load disk images and files into RAM (insofar as free memory is available). At this point WHDLoad performs its main task of switching off the AmigaOS operating system, disables multitasking and interrupts, and copies memory regions which are used by AmigaOS and required by the installed program to an unused place until the AmigaOS is needed again. WHDLoad also degrades the graphics hardware to OCS on original Amiga machines (this function actually can work also on emulated Amigas, but only on newer versions of WinUAE which recognizes WHDLoad and preserves its interrupts), then WHDLoad initializes all hardware with defined values and jumps into the Slave interface required for the program in question. The Slave interface loads the main

executable In computing, executable code, an executable file, or an executable program, sometimes simply referred to as an executable or binary, causes a computer "to perform indicated tasks according to encoded instruction (computer science), instructi ...

of the installed program by calling a WHDLoad function (''resload_DiskLoad'' or ''resload_LoadFile''), then patches the main executable (so that the loaded program will be capable of loading its data stored into the hard disk via the Slave, in order to fix compatibility problems, and to enable an exit from the program) and calls the main executable. At this point, the program that has been installed can perform the task for which it has been written, loading its data as it would from a real floppy disk. Users can break the execution of the loaded program by way of a "Quit" key (usually F10). When this action is performed, then the Slave interface returns to WHDLoad by calling a ''resload_Abort'' internal function. The OS will be restored with all hardware registers and original display. The memory and all allocated resources are left free for any further usage.

Requirements

A standard Amiga 1200 or

Amiga 600 The Amiga 600, also known as the A600, is a home computer introduced in March 1992. It is the final Amiga model based on the Motorola 68000 and the 1990 Amiga Enhanced Chip Set. A redesign of the Amiga 500 Plus, it adds the option of an internal ...

without any extra memory, will only work with a limited number of games. Which usually means games using OCS/ ECS and one

. It is recommended to install either a or RAM Board in the trapdoor slot to ensure compatibility for 99% of the games. A harddisk is required, the number of games that can be installed depend on the size of the harddisk.

References

External links

whdload.de: WHDLoad home page