Here is one idea for doing a multicart using the 2600 to provide a
menu interface... I'll use a 127-in-1 cart as an example.
$00000-$00EFF menu interface
$00F00-$00FFF menu B/S area
$01000-$01FFF 1st game
$02000-$02FFF 2nd game
...
$7F000-$7FFFF 127th game
you could use a 512K FLASH like a AMD 29F400 for this.
Set up some address decode logic so on power-up, A18-A11 are all 0.
When an address with A10-A7 set to 1 is read, latch the low 7 bits of
the address unto bits A18-A11 of the flash's address bus. At this
point we will need to force a jump to the reset vector, either by
holding off on the BS for a few cycles and doing it in software or by
forcing the jump command on the bus.
I'd anticipate the logic to hold the address bus until power-off.
This would be easy with a small microcontroller -- the only limitation
is the eightteen required I/O lines and possibly clock generation.
That number could be reduced a little by some external glue logic,
however.
With some extra logic and decoding on the MCU, you could even
implement one of the common BS methods, like the Activision or Atari
8K ones. That would let you do a multicart for games larger than 4K.
--
Benjamin L. Combee (combee@xxxxxxxxxxxx) <URL:http://www.yak.net/combee/>
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