Amiga Halfbrite mode
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Extra Half-Brite,[1][2] usually abbreviated as EHB, is a planar display mode of the Amiga computer.
This mode uses six bitplanes (six bits/pixel).[3][4][5] The first five bitplanes index 32 colors selected from a 12-bit color space (4096 possible colors). If the bit on the sixth bitplane is set, the display hardware halves the brightness of the corresponding color component.[6] This way 64 simultaneous colors are possible (32 arbitrary colors plus 32 half-bright components) while only using 32 color registers.[7] The number of color registers is a hardware limitation of pre-AGA chipsets used in Amiga computers.
Some contemporary game titles and animations used EHB mode as a hardware-assisted means to display shadows or silhouettes.[8] EHB was also often used as general-purpose 64 color mode with the aforementioned restrictions.[9][10][11][12]
Some early versions of the first Amiga, the Amiga 1000 sold in the United States lack the EHB video mode, which is present in all later Amiga models.[13][14]
See also[edit]
References[edit]
- ^ Mortimore, Eugene P. (1986). Amiga Programmer's Handbook. SYBEX. ISBN 978-0-89588-343-8.
- ^ Maher, Jimmy (2018-01-26). The Future Was Here: The Commodore Amiga. MIT Press. ISBN 978-0-262-53569-4.
- ^ "3 / Color Selection / Color Selection in Extra Half Brite (EHB) Mode". amigadev.elowar.com. Retrieved 2022-11-19.
- ^ "Retroshowcase:oldschool game reference!". www.retroshowcase.gr. Retrieved 2022-11-19.
- ^ "Amiga (1988) | IEEE Computer Society". Retrieved 2022-11-19.
- ^ Maher, Jimmy (2018-01-26). The Future Was Here: The Commodore Amiga. MIT Press. ISBN 978-0-262-53569-4.
- ^ Inc, Commodore-Amiga (1992). Amiga ROM Kernel Reference Manual: Libraries. Addison-Wesley. ISBN 978-0-201-56774-8.
{{cite book}}:|last=has generic name (help) - ^ "Amiga Graphics Archive – Amiga Graphics Archive". amiga.lychesis.net. Retrieved 2022-11-19.
- ^ "Extra Half Bright (EHB)". Amiga Graphics Archive. Retrieved 19 September 2011.
- ^ "Amiga Graphics Archive - EHB". Amiga Graphics Archive. Retrieved 19 September 2011.
- ^ Compute. Small System Services. 1989.
- ^ "Kroah's Game Reverse Engineering Page - The Bard's Tale serie - Bard's Tale Construction Set". bringerp.free.fr. Retrieved 2022-11-19.
- ^ "Amiga Animations | Blair-Sullivan Computer Graphics & Animation | HalfBrite Hill". www.randelshofer.ch. Retrieved 2022-11-19.
- ^ Maher, Jimmy (2018-01-26). The Future Was Here: The Commodore Amiga. MIT Press. ISBN 978-0-262-53569-4.