[atari7800] Re: Why do DLLs have to be in RAM?

The 2600 CPU clock is 1.19MHz (1/3 colorburst) while the 7800 CPU clock is
1.79MHz (1/2 colorburst, 50% faster than the 2600); which is why the 7800
CPU has to downshift to 1.19MHz to access the RIOT and TIA (because those
parts can only handle the lower clock rate).

The 2600 TIA internally uses the colorburst clock (3.58MHz) to generate the
graphics, but doesn't access RAM/ROM itself.  Not only does the 7800 MARIA
use a 7.16MHz clock (2x colorburst) internally, but it accesses RAM & ROM.
Each MARIA clock is ~140ns,  but the RAM and ROM of the day wouldn't have
had access times low enough to support it.  So the RAM is probably 250ns (2
MARIA cycles) and the ROM is max 400ns (3 MARIA cycles).

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