Quote:
Originally Posted by mc6809e
Page mode certainly did exist at the time. The Acorn Electron (1983) used it to cleverly reduce the number of dram chips from eight to four. It actually had a four bit bus. Page mode was exploited to grab two nibbles to create each needed byte.
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Dig then for 4164 technology as it was common when Amiga become WIP:
(1981) Fairchild 4164 - support Page Mode
(1980) TI 4164 - support Page Mode
(1981) Toshiba 4164 - support Page Mode
(1982) OKI 4164 - support Page Mode
(1980) Mostek 4164 - support Page Mode
(1980,1981/1982) Motorola (MCM6664) 4164 - doesn't support Page Mode
(1982) Motorola (MCM6664A) 4164 - does support page mode
Page Mode was also unavailable in some 41256 DRAM's - my impression is that Amiga designers avoided exploring this due few reasons - one of them was that Page Mode was not industry standard before 1984 and they willing to avoid situation being too dependent but also adding Page Mode require more complex design (more FETCH logic, higher complexity etc), also i think they anyway considered Amiga design as impressive so no need to increase memory bandwidth.
Quote:
Originally Posted by mc6809e
Not sure what you mean by buffering, but Denise and Paula already store multiple bytes before they're needed. Paula stores two byes per channel and Denise stores up to six words for display.
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Single WORD is not so much - i case of the FPM you will need to at least double this size or even more - this is like FMODE coding rules with AGA - also alignment need to be considered and avoiding page crossing at all cost.
Quote:
Originally Posted by mc6809e
Interestingly the Atari ST has a video memory organization that combines both the idea of bitplanes and linear organization with a bitplane words interleaved with each other sequentially in memory.
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But this can be explained by simpler bitplane organization - you have only 1, 2 or 4 bitplanes where Amiga may have 1,2,3,4,5, and 6 bitplanes also
with Dual Playfield in action... as such it was way easier to design chunky-planar ST organization than pure planar (Amiga of course at a cost of additional logic could introduce similar but then at least some limitations need to be introduced).
Quote:
Originally Posted by mc6809e
Look, I'm not bashing the Amiga. I love it. There were just a few regrettable choices made.
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it is not about bashing, i can regret those choices same as you but trying to understand way of thinking and also see some limitations - if Amiga could be designed after 1985 i'm quite sure that it will use FPM, perhaps interleaving, more RAM, more colors etc. So it will be like Ranger from very beginning...
We must see both sides of problem...
Even simple DRAM refresh - check Toni very interesting information - how inconsistent was Commodore in terms of DRAM refresh - this DRAM feature was not also industry standard till at least 1985 - so many versions across those times.
http://eab.abime.net/showpost.php?p=...&postcount=290
http://eab.abime.net/showpost.php?p=...&postcount=294