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Open Source, DIY 512KB RAM Expansion

Started by revaldinho, 22:10, 24 April 18

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eto

Quote from: llopis on 18:23, 12 October 23I'm working on a video about a similar RAM upgrade for the CPC and I was wondering what are some of the best demos/games/apps that showcase having more than 128KB of RAM. I already have FutureOS and SymbOS in the list. Anything else that you would say is really cool? Any dev environments (on the CPC itself) that can use that much RAM for something useful?
I asked a similar question a year ago, there wasn't a lot of examples that really benefit from more than 128K: https://www.cpcwiki.eu/forum/amstrad-cpc-hardware/what-memory-expansion-size-to-choose/msg220291/#msg220291

Afaik @zhulien is working on some projects that will take advantage of a lot of RAM. 

zhulien

#176
yes,

MCP (master control program); currently allows different background tasks in AMSDOS 1 per 16kb bank - this is a POC which is reasonable code that doesn't need throwing away.  The idea is to make hardware drivers available to AMSDOS in a standard manner - in a way that get adopted.  This set of drivers likely will also be compatible with PrimalOS - which isn't specifically AMSDOS, but can run on top of AMSDOS too.

I have already coded POCs of memory allocations and such for support up to 4mb RAM - as in a heap.  This uses 24 bit addressing.  I have designed the virtual memory logic to cater for up to 16mb RAM (4mb physical) - using packed far addresses too, the benefit is not to have 16mb RAM, but to allow 128kb systems run software that requires more RAM but allowing systems with 1mb, 2mb, 4mb to run optimally.  If a compiler or assembler catered for what I need here now, it would be sooner than later, but I need to put support in here for my compiler so that it's easy to write large software that also works on 128kb systems (pretty fast) or 64kb systems (pretty slow - but runs).  I am actually almost settled on 4mb RAM ceiling with 64 byte block size instead of 16mb RAM ceiling with 256 byte block size.  But... I guess it would be relatively easy to make 2 separate builds if we ever got a 16mb RAM expansion.  I can elaborate more later, but you cna read the RAM tab here: https://docs.google.com/spreadsheets/d/1XgRVlh27K_C0-gMtroMhN8lK9mAQxVQg1x-3M42kBYo/edit?usp=sharing  Of all the allocation / deallocation tests I have created and coded, the RAT (RAM Allocation Table) method seems to be the best balance for performance and accessibility for a Z80 system with lots of RAM rather than worrying about the loss of every single byte and catering for 24 bit far addresses and tralling long linked lists to find free blocks.

I have been playing with modified locomotive BASIC to improve the ways it uses RAM too. 

RAM usage: I am looking at a solution that to me is the "right way of doing things" on a CPC.  Goal: plug in memory, run some software (MCP? Primal? which initialises RAM and drivers), run applications or games that use the RAM and drivers in a nice way without trashing everything.

Should every CPC owner have at least 576kb RAM? ABSOLUTLY!!!  YES YES YES x 576 times.

zhulien

Quote from: llopis on 18:23, 12 October 23I'm working on a video about a similar RAM upgrade for the CPC and I was wondering what are some of the best demos/games/apps that showcase having more than 128KB of RAM. I already have FutureOS and SymbOS in the list. Anything else that you would say is really cool? Any dev environments (on the CPC itself) that can use that much RAM for something useful?
Try Alyssa Database as reviewed in CPC Attack!

Anthony Flack

#178
My Bomb Jack remake requires 128k and a disk drive but the eventual intention is to have it detect if 256k is available and load the entire game (title screen, all backgrounds) into memory at once. I don't have 256k of memory to test with but I guess I'll figure it out.

I do have an M4 board and running the game from that is very fast and I like that; using an extra 128k as a ram disk seems like a worthwhile thing to add for people who have it.

Also it should make for a truly epic disk-grinding session when loading the whole thing from the floppy drive.

eto


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