peter@cbmvax.commodore.com (Peter Cherna) (05/05/90)
Following a specific request I received, and some general confusion, I
thought I should present a discussion of the complete set of modes
supported by ECS and AmigaOS 2.0.
Mode Name Size Color Monitor Type De-Interlacer Notes
Lores 320x200 (A) NTSC Scan-doubles (1)
Lores-Interlaced 320x400 (A) NTSC De-interlaces (1)
Hires 640x200 (B) NTSC Scan-doubles (1)
Hires-Interlaced 640x400 (B) NTSC De-interlaces (1)
Lores 320x256 (A) PAL Scan-doubles (2)
Lores-Interlaced 320x512 (A) PAL De-interlaces (2)
Hires 640x256 (B) PAL Scan-doubles (2)
Hires-Interlaced 640x512 (B) PAL De-interlaces (2)
SuperHires 1280x200 (C) NTSC disable it (*) (3,7)
SuperHires-'lace 1280x400 (C) NTSC disable it (*) (3,7)
SuperHires 1280x256 (C) PAL disable it (*) (3,7)
SuperHires-'lace 1280x512 (C) PAL disable it (*) (3,7)
Productivity 640x480 (C) VGA pass-through (4,7)
Productivity-'lace 640x960 (C) VGA pass-through (4,7)
A2024-10Hz 1008x800 (D) A2024 (NTSC) N/A (5)
A2024-15Hz 1008x800 (D) A2024 (NTSC) N/A (5)
A2024-10Hz 1008x1024 (D) A2024 (PAL) N/A (6)
A2024-15Hz 1008x1024 (D) A2024 (PAL) N/A (6)
Size:
The nominal sizes of each mode are given. The regular NTSC and PAL
modes can be overscanned. TheSuperHires NTSC and PAL modes can
also be overscanned, though less that proportionately to the regular
NTSC or PAL modes. The two productivity modes can also be overscanned.
The A2024 modes may not be overscanned.
Colors Notes:
(A): 2, 4, 8, 16, 32, 64(EHB), or HAM, from a palette of 4096.
(B): 2, 4, 8 or 16 from a palette of 4096.
(C): 2 or 4 from a palette of 64.
(D): 2 or 4 shades of gray.
Signal Type:
NTSC: Requires NTSC-type monitor, including 1080, 1084, television.
Some PAL-type monitors also can handle NTSC.
Most (?) multiscanning monitors can support NTSC rates.
PAL: Requires PAL-type monitor, including PAL 1080, 1084, television.
Some NTSC-type monitors also can handle PAL.
Most (?) multiscanning monitors can support PAL rates.
VGA: Requires VGA-class or multiscanning monitor.
A2024 (NTSC): Requires NTSC version of A2024 monitor.
A2024 (PAL): Requires PAL version of A2024 monitor.
De-Interlacer:
The de-interlacer is a circuit on the A3000 motherboard that works
with a VGA-class or multiscanning monitor.
When enabled, the de-interlacer provides a VGA-compatible output on
its 15-pin connector, from what would be NTSC or PAL or VGA modes from the
23-pin video connector. To use this, you require a VGA-class or
multiscanning monitor.
De-interlacing means that instead of pushing out two fields in alternation
at 60 (NTSC) or 50 (PAL) fields per second (30 or 25 full screens per
second), the de-interlacer buffers one field and pushes it out with the
other, so that both fields come out together, for 60 or 50 non-flickering
full screens per second.
Scan-doubling means that a single (non-interlaced) field is pushed out
twice as fast, and is replicated on adjacent lines. The result is
a solid display of color, with no visible scan-lines.
(*) The SuperHires modes require that you disable your de-interlacer. If
you do, then the output from the 15-pin connector will become NTSC or PAL
rate, and will not be scan-doubled or de-interlaced. If you leave
the de-interlacer on, you will get a de-interlaced or scan-doubled
display, though you will only see every second pixel horizontally, since
the display-enhancer is sampling for 640 (plus overscan) pixels per
line, and not the 1280 pixels that are being generated.
Pass-through means that the de-interlacer detects these modes and
passes them through directly to the 15-pin VGA connector.
N/A is because the A2024 plugs in to the 23-pin video connector, and
doesn't come near the de-interlacer and its 15-pin connector.
Notes:
(1) Requires NTSC Amiga or any Amiga with Super Agnus.
(2) Requires PAL Amiga or any Amiga with Super Agnus.
(3) Requires Super Agnus and Super Denise, and AmigaOS 2.0.
(4) Requires Super Agnus and Super Denise, and AmigaOS 2.0.
(5) Requires NTSC A2024 (with JumpStart or with AmigaOS 2.0)
(6) Requires PAL A2024 (with JumpStart or with AmigaOS 2.0)
(7) These modes take up twice the bandwidth of a comparable Hires mode,
so Super-Hires Interlaced 4 colors is comparable in bandwidth to
Hires-Interlaced 16 colors. As well, there is only one sprite
available.
Other modes:
For completeness, I should note that there are also some smaller members
of the Productivity family that output VGA-class signals, and have
resolutions of 320 x 480, 320 x 960 (interlaced), 160 x 480, and
160 x 960 (interlaced). These modes were basically "free" given that
we have Productivity mode, but they aren't particularly useful.
Peter
--
Peter Cherna, Software Engineer, Commodore-Amiga, Inc.
{uunet|rutgers}!cbmvax!peter peter@cbmvax.cbm.commodore.com
My opinions do not necessarily represent the opinions of my employer.
"If you insist on spending $10000 on a 68030 technology, may we humbly
suggest you buy three Amiga 3000's."