LoadROM doesn't load roms... freezes after awhile instead.

By metallica_tyler

Rookie (31)

metallica_tyler's picture

27-08-2005, 08:10

I made a bootable MSX-DOS2 Floppy w/ a rom image and the loadrom command file. I type in loadrom and it goes through and says it's loading the "whatevername.rom" file. These files are all under 256KB that i'm testing. Anyways it goes from 0.......................12 then freezes and doesn't load anything. What's wrong?

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By mars2000you

Enlighted (6014)

mars2000you's picture

27-08-2005, 09:47

For megaroms, LoadROM needs always a RAM size that is higher than the size of the ROM game.

Example : for a ROM game of 128 Kb, LoadROM needs 256 KB RAM.

Besides, some little roms that use the MSX-BASIC are not supported by LoadROM.

By BiFi

Enlighted (4348)

BiFi's picture

27-08-2005, 09:54

most likely not enough memory... crash course ROM images in RAM... there are a few types of ROM images... almost all ROM images of 8 KB, 16 KB or 32 KB will work perfectly. Larger ROM images are usually MegaROM images. There are basically 2 types of MegaROM structures: switching banks of 8 KB and in 16 KB...

The easiest MegaROMs to run from RAM are the ones with banks of 16 KB because RAM works with the same size. You actually need 256 KB of RAM to run an 128 KB MegaROM (16 KB banks). The reason for this is there is an amount of RAM required for the game's data. For this there is 16 KB of RAM you can't use... and when you're using MSX-DOS 2 the system claims 32 KB for itself. For a 256 KB MegaROM (16 KB banks, you usually need 512 KB.

The MegaROMs with banks of 8 KB are a bit more complicated... To run those in RAM (with 16 KB banks) LOADROM needs to scan for the combinations of 2 8 KB banks to make a functional 16 KB bank to put in RAM. It's possible 1 8 KB bank is used in more combinations. All these combinations may cause to require even more RAM than the actual size of the ROM image.