Goity posted on Apr 3 2005 at 02:42 AM said:
fdave posted on Apr 3 2005 at 01:39 AM said:
tekt5 posted on Apr 2 2005 at 07:49 PM said:
The GBA has MANY special chips that are hard to emulate.. like the amiga
This is one of those posts which makes me go... hmmmm.... twice
The first hmmmm is because surely the GBA is one of the nicest systems, I imagine would be quite nice to emu. But I don't know for sure. I can think of lots of systems which are much worse though I reckon. So... hmmmmmm
yes, Hmm.... Actually, the GBA only has a graphics chip, something like 512kb I believe, not Doris and Norman and all that shite they put in the amiga.
Ahem... ""Agnus" and "Denise" were responsible for effects timed to the
real-time position of the video scan, such as midscreen
palette changes, sprite multiplying, and resolution
changes. Different versions (in order) were: "Agnus" (could
only address 512K of video RAM), "Fat Agnus" (in a PLCC
package, could access 1MB of video RAM), "Super Agnus"
(slightly upgraded "Fat Agnus"). "Agnus" and "Fat Agnus" came
in PAL and NTSC versions, "Super Agnus" came in one
version, jumper selectable for PAL or NTSC. "Agnus" was
replaced by "Alice" in the A4000 and A1200, which allowed for
more DMA channels and higher bus bandwidth.
"Denise" outputs binary video data (3*4 bits) to the "Vidiot".
The "Vidiot" is a hybrid that combines and amplifies the
12-bit video data from "Denise" into RGB to the monitor.
Other chips were "Amber" (a "flicker fixer", used in the A3000
and Commodore display enhancer for the A2000), "Gary" (I/O,
addressing, G for glue logic), "Buster" (the bus
controller, which replaced "Gary" in the A2000), "Buster II"
(for handling the Zorro II/III cards in the A3000, which meant
that "Gary" was back again), "Ramsey" (The RAM controller),
"DMAC" (The DMA controller chip for the WD33C93 SCSI adaptor
used in the A3000 and on the A2091/A2092 SCSI adaptor card for
the A2000; and to control the CD-ROM in the CDTV), and
"Paula" (Peripheral, Audio, UART, interrupt Lines, and
bus Arbiter).
There were several Amiga chipsets: the "Old Chipset" (OCS),
the "Enhanced Chipset" (ECS), and AGA. OCS included
"Paula", "Gary", "Denise", and "Agnus".
ECS had the same "Paula", "Gary", "Agnus" (could address 2MB
of Chip RAM), "Super Denise" (upgraded to support "Agnus" so
that a few new screen modes were available). With the
introduction of the Amiga A600 "Gary" was replaced with
"Gayle" (though the chipset was still called ECS). "Gayle"
provided a number of improvments but the main one was support
for the A600's PCMCIA port.
The AGA chipset had "Agnus" with twice the speed and a 24-bit
palette, maximum displayable: 8 bits (256 colours), although
the famous "HAM" (Hold And Modify) trick allows pictures of
256,000 colours to be displayed. AGA's "Paula" and "Gayle"
were unchanged but AGA "Denise" supported AGA "Agnus"'s new
screen modes. Unfortunately, even AGA "Paula" did not support
High Density floppy disk drives. (The Amiga 4000, though,
did support high density drives.) In order to use a high
density disk drive Amiga HD floppy drives spin at half the
rotational speed thus halving the data rate to "Paula"."
Dictionary.com
Education is mah middle name. B)