Hi,
Megaram is a brazilian dynamic RAM cartridge with 8Kb banks, exactly
like Konami megaroms. But it has a mode control port (8EH).
Performing a write to the port 8EH you put the cartridge in ROM mode.
It means that you can only select the banks shown in pages 1-2 just as
the game originally does.
Performing a read from the port 8EH you put the cartridge in RAM mode.
In this mode the data you write in pages 1-2 are stored in the RAM shown
at these address. The bank selection is disabled in this mode.
Here we have Megarom games splited in 16 Kb blocks, with a loader in
ML/BASIC. The loader loads a block into page 2 of RAM, put the Megaram
in ROM mode, selects the desired banks of Megaram at the page 1, put the
Megaram in RAM mode and performs an LDIR. This loop is repeated 8 or 16
times until the whole game is loaded into Megaram. Then the loader set
the ROM mode and resets the MSX or boot the game on Megaram. And now you
have a RAM cartridge with a megarom game loaded into it, looking to the
MSX exactly like a ROM cartridge. You can even reset the MSX by
hardware, that the game stands there.
Some Megarams have an EPROM with MSXDOS1, and work like a ramdisk drive
(B: or C:), but they dont have a battery and refresh for keeping data
when msx is turned off. They are called megaram-disk. There are just
256, 512 and 768 Kb models, although its maximum possible size is 2Mb
(256 x 8 Kb).
The first Megaram was originally made in 1987 by Ademir Carchano, and
he is still selling it. Contact him at:
[EMAIL PROTECTED]
Thanks
Werner Kai
