AHI (Amiga)

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AHI (AHI audio system) is a retargetable audio subsystem for AmigaOS, MorphOS and AROS. It was created by Martin Blom in the mid-1990s to allow standardized operating system support for audio hardware other than just the native Amiga sound chip, for example 16-bit sound cards. [1]

AmigaOS native operating system of the Amiga personal computer

AmigaOS is a family of proprietary native operating systems of the Amiga and AmigaOne personal computers. It was developed first by Commodore International and introduced with the launch of the first Amiga, the Amiga 1000, in 1985. Early versions of AmigaOS required the Motorola 68000 series of 16-bit and 32-bit microprocessors. Later versions were developed by Haage & Partner and then Hyperion Entertainment. A PowerPC microprocessor is required for the most recent release, AmigaOS 4.

MorphOS is an AmigaOS-like computer operating system. It is a mixed proprietary and open source OS produced for the Pegasos PowerPC processor based computer, PowerUP accelerator equipped Amiga computers, and a series of Freescale development boards that use the Genesi firmware, including the Efika and mobileGT. Since MorphOS 2.4, Apple's Mac Mini G4 is supported as well, and with the release of MorphOS 2.5 and MorphOS 2.6 the eMac and PowerMac G4 models are respectively supported. The release of MorphOS 3.2 added limited support for PowerMac G5. The core, based on the Quark microkernel, is proprietary, although several libraries and other parts are open source, such as Ambient desktop.

AROS Research Operating System operating system

AROS Research Operating System is a free and open-source multi media centric implementation of the AmigaOS 3.1 APIs. Designed to be portable and flexible, ports are currently available for x86-based and PowerPC-based PCs in native and hosted flavors, with other architectures in development. AROS, in a show of full circle, was also ported to the m68k-based Amiga 1200, and there's also an ARM port for the Raspberry Pi series.

AHI offers improved functionality not available through the AmigaOS audio device driver, such as seamless audio playback from a user selected audio device (in applications which supported AHI), standardized functionality for audio recording and efficient software mixing routines for combining multiple sound channels thus overcoming the four channel hardware limit of the original Amiga chipset. [2] It also incorporated a unique mode that produced 14-bit playback using the Amiga chipset by combining two 8-bit channels set at different volumes. [1] The first official release of AHI was in 1996. [3] AHI became a widely supported standard for audio hardware and audio software on Amiga systems and was officially included in later operating system releases.

The author has stated that when referring to this software the correct term is 'AHI audio system' or just 'AHI' and not 'Audio Hardware Interface', [4] term sometimes used by the press. [1] [5] [6]

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References

  1. 1 2 3 Goodwin, Simon (October 1997). "AHI". Amiga Format. No. 102. Future Publishing. pp. 24–26. ISSN   0957-4867.
  2. ↑ Březovský, Boleslav (January 1997). "AHI Audio System". Amiga Review (in Czech). No. 24. Atlantida Publishing. pp. 18–19. ISSN   1211-1465.
  3. ↑ "Martin Blom's home page - martin.blom.org".
  4. ↑ Martin, Blom (2006). "m68k-amigaos-ahiusr Aminet Readme".
  5. ↑ Drummond, Richard (December 1999). "AHI PPC Preview". Amiga Format. No. 130. Future Publishing. p. 54. ISSN   0957-4867.
  6. ↑ Korn, Andrew (February 1997). "Audio Hardware Interface". CU Amiga. No. 84. EMAP. pp. 62–63. ISSN   0963-0090.


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