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[Vag]

Hello.
I don't know AMOS but I'm writing an editor for .CUT and .DOG files that are used in the Flight of the Amazon Queen. This is an adventure game that was originally written in AMOS.
These files were created with AMOS and here I found the specifications.
It doesn't really matter for my purpose, but does anyone know anything about usin chip and fast memory?
There are 4 flags, "Chip memory bank", "Fast memory bank", "Try chip memory" and "Try fast memory". What if you set them all to true for example?

[Sidewinder]

Welcome Vag,

To answer your question directly, the classic Amiga divided memory into Chip and Fast RAM.  The terms are mutually exclusive.

Chip RAM was memory that could be accessed by the Amiga's custom chips.  This required all graphics and sound data to be loaded into chip RAM prior to use.  Most Amigas had only about 512k of Chip RAM, but some had up to 2 Megs.

All other RAM on the Amiga was called Fast RAM.  It could only be accessed by the 68000 processor and for some reason (which I'm forgetting right now) it was considered "faster" than Chip RAM.

My guess is that these flags were set to indicate to the load routine which area of memory the bank should be copied to.  Graphics and sound data was usually put into chip memory.  Other data, like game map data, or custom data, could be placed in fast memory if there was any available.

The meaning of the flags is as follows:

"Chip memory bank" == Load the bank into chip memory if any is available, otherwise fail.

"Fast memory bank" == Load the bank into fast memory if any is available, otherwise fail.

"Try chip memory" == Load the bank into chip memory if any is available, otherwise load it into fast memory if any is available.

"Try fast memory" == Load the bank into fast memory if any is available, otherwise load it into chip memory if any is available.


My guess is that setting them all TRUE will either cause an error or just cause the bank to be loaded into chip RAM (since it's the first flag and would probably be executed first if it was TRUE).

I'm not sure what would happen if you didn't set any flags.  Probably a load failure.

Typically only one flag should be set to indicate the desired memory preference.

I hope that helps.

[Vag]

I understand, thank you. As I stated before, this is not vital but it helps.

[Mindie]

@Sidewinder:

The reason it was called "fast" mem, is very simple, actually. The CPU had to wait for access to the chipram (where all the custom chips would also read from) and was therefore slow, while as there was no waitstates to the fastram and could thus access the data there straight away.

Espeically on the aGA machines (A1200 and A4000) the FAST ram mean a significant speedincrease for some programs.