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Old 08 December 2017, 09:37   #141
LocalH
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Dynamic Hires/SHAM is not real HAM6. True HAM6 relies on the hardware allowing the standard "hold-and-modify" technique to access non-paletted colors, and can easily generate more than 16 colors on a single scanline. SHAM/dynamic hires simply changes up to 16 colors per line on a 16-color hires display, and can not access colors that aren't on the palette for a given scanline.

There is no way prior to AGA to use HAM6 on anything but lores.
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Old 08 December 2017, 11:04   #142
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There is no way prior to AGA to use HAM6 on anything but lores.
Why was it that the OCS/ECS Amigas were limited to 16 colours in hires and no HAM, but the AGA Amigas were able to achieve ridiculously high resolutions AND colour depths like Super Hires HAM8, albeit at the cost of speed? I've never understood this "unshackling of graphical limitations" between chipsets.
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Old 08 December 2017, 14:09   #143
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Hardware and custom chips are designed with constraints:
- Time
- Money
- What is good enough at the time

4096 colours was good enough at the time and the ICS/OCS chipset had a maximum Chip RAM space of 512k. You can't fit a lot of stuff in there anyway, so the limits they deemed "good enough" were ok for the machine the chips were going to go in to.

AGA came six years later, RAM prices had fallen and micro chip fab techniques had gone forward to enable higher speeds / larger chips with more pins.
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Old 08 December 2017, 14:22   #144
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Originally Posted by Foebane View Post
Why was it that the OCS/ECS Amigas were limited to 16 colours in hires and no HAM, but the AGA Amigas were able to achieve ridiculously high resolutions AND colour depths like Super Hires HAM8, albeit at the cost of speed? I've never understood this "unshackling of graphical limitations" between chipsets.
It's just a question of bandwidth. The "unshackling" was done by making the Chip RAM bus 32-bits wide instead of 16-bits wide, and by doubling the transfer rate between the Chip RAM and chipset, which means AGA in its fastest fetch mode can fetch 64 bits of data in the same time ECS takes to fetch 16 bits.
These improvements were possible due to advances in technology, improved speeds, miniaturisation, surface-mount techology for circuit boards (routing a 32-bit data bus for chips with through-hole pins? Not anyone's idea of fun!), and not least, the falling costs of more advanced tech.

The real tragedy is that only the bitplane hardware was able to make use of this extra bandwidth, and the audio, disk and blitter weren't updated.
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Old 08 December 2017, 14:56   #145
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Buying an off the shelf chip and drive could have been easier and cheaper to start with but when you are fabbing your own chips would that have been cheaper once you go over 100k units?
Were there licencing issues?
If you use the off the shelf, would you have to licence the code from WD to read/write to the format in your OS?
CBM didnt like to spend money on that sort of thing


CBM didnít design the Amiga though. Amiga Inc did. Its just my opinion but I think they would have got to market sooner with more standard parts and have had more money left over. Plus we would have an easier time maintaining the machines.
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Old 08 December 2017, 15:12   #146
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CBM didnít design the Amiga though. Amiga Inc did. Its just my opinion but I think they would have got to market sooner with more standard parts and have had more money left over. Plus we would have an easier time maintaining the machines.
This happened in the Atari land with the ST (The Jackintosh). Both Macs and Atari's used mostly off the shelf parts - one of them succeeded, the other miserably failed.
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Old 08 December 2017, 22:21   #147
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Originally Posted by Foebane View Post
Why was it that the OCS/ECS Amigas were limited to 16 colours in hires and no HAM, but the AGA Amigas were able to achieve ridiculously high resolutions AND colour depths like Super Hires HAM8, albeit at the cost of speed? I've never understood this "unshackling of graphical limitations" between chipsets.
For the same reason your C64 and ZXSpectrum didn't have hardware accelerated 3D graphics cards, nor quad-core GHz-class CPUs and GBs of RAM.
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Old 09 December 2017, 22:40   #148
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This happened in the Atari land with the ST (The Jackintosh). Both Macs and Atari's used mostly off the shelf parts - one of them succeeded, the other miserably failed.


Donít think that either was a failure. ST and Mac both sold in good numbers. Atari and Amiga both suffered from the rise or PCs. Apple barely survived that period then rose again
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