what memory expansion size to choose?

[eto]

Does it make sense to add more than 256K or 512K additional RAM to a CPC? I know that FutureOS and SymbOS support more RAM but are there any applications or games that also take advantage of the additional RAM above 512KB?  Anything relevant that will only run with more than 512KB? Or at least be much more convenient with more than 512KB?

[TotO]

The 80s standard on CPC was 256K, mostly used by tools like Discology, not games neither demo.
Extra 256K (512K total) was usually used to add a RAM Drive (Silicon Disk), more than real RAM for programs.

[Gryzor]

Was there any, say, database program that could load huge files into memory, even with paging? 

[eto]

Was there any, say, database program that could load huge files into memory, even with paging?

Not sure when the Yarek/RAM7 Addressing scheme came up, but I guess it was way after any such program came out. 

[zhulien]

Alyssa Database by myself supports 512kb extra RAM.

[Prodatron]

E.g. I know about these productions, where I am not sure, if you could call them "relevant":

- Shinings
Bad Apple demo requires 1MB ram
- a lot of Devilmarkus musik sample demos, using my AY stereo sample player, support up to 4MB
- CPC Word supports up to 576K

[zhulien]

Is that 4mb or 4mb plus the 64k?

[Gryzor]

Ooh yes CPC Word is a nice one!

[eto]

E.g. I know about these productions, where I am not sure, if you could call them "relevant":

- Shinings
Bad Apple demo requires 1MB ram
- a lot of Devilmarkus musik sample demos, using my AY stereo sample player, support up to 4MB
- CPC Word supports up to 576K

thanks a lot. "Relevance" is of course a matter of opinion and personal preferences, so I'm happy to see examples.

Are there any games that run only with >128K or work better with >128K?

Since you are probably the best person to ask: In SymbOS, what works only/better with 1MB than with 512K?

[Prodatron]

Since you are probably the best person to ask: In SymbOS, what works only/better with 1MB than with 512K?

Nothing. You just have more ram and can load more stuff and run more applications at the same time. It's all dynamic like on a modern PC and operating system.
IMHO 576K is fine for most things. But with 1 MB you can e.g. start the browser 15times
You cannot view this attachment.

Are there any games that run only with >128K or work better with >128K?

Outside SymbOS I don't know of any. In SymbOS there are several applications and games which won't run on a naked 128K system, as SymbOS already requires around 80K by itself.

[Prodatron]

Is that 4mb or 4mb plus the 64k?

The first 64K are always seperate. So total RAM is 64K + memory expansion size (for those with 512K or more).

[GUNHED]

Well, the 4 MB Exp-RAM size is getting to be a standard (hopefully one day), but very slowly sadly.
Some software I did supporting 4 MB, but it would be great if there would be much more support for it.

[zhulien]

we are lucky we have a CPC that can load fast from drives - I love this video from 19mins in, how it is sped up 50x loading from mass storage - on the C64 and it STILL takes a minute!  Imagine loading for 50 minutes from sdcard or similar

[TotO]

Well, the 4 MB Exp-RAM size is getting to be a standard, but very slowly sadly. Some software I did supporting 4 MB, but it would be great if there would be much more support for it.

While many users do not want to use more than 64KB since 30 years ago and few programs really use 512KB since 10 years ago, I'm not sure that will be a big step to require 4MB RAM. In fact, using ROM cartridges or a mass storage for new programs tend to reduce the real RAM usage today.

[zhulien]

On a single real cpc we can now have 2 hxc drives with 64gb storage each (maybe bigger haven't tested), a 512mb x-mass (any success with larger yet @TotO), m4 with 64gb, and i guess 2 Albieros with huge amount of remote storage. Then all can be used at once with unidos (except the hxc currently need floppies images for now, not native) plus a massive remote ftp site.  I guess I can put a massive movie collection now on cpc - just need a movie player for it to make it a media centre.

[XeNoMoRPH]

Programs that use 256 kb of ram:
-----------
Discology
Orgams assembler
Punishment v1.0
Alyssa Database
Pyradev is a complete utility from Discovery Software.
Hackit ROM
JL-Copy Utilities COPY Utilities v2
Disc'O'Magic v4.1

Games:
--------
ChibiAkumas Episode 2

 

 

[TotO]

@zhulien If you remember, 32-bit 100MHz+ 486/Pentium PC running Doom was using 80/120MB HDD. Pentium III with 500MHz+ running Quake 3 was using 512MB/1TB HDD. All the CPC games/tools fit into around 200MB. Using at less only one 64GB storage on a 8-bit 4MHz CPC looks to me so supernatural. How long to fill and read them at 150kB/s ? 25 years no-stop?

[roudoudou]

Programs that use 256 kb of ram:
-----------
Discology
Orgams assembler
Punishment v1.0
Alyssa Database
Pyradev is a complete utility from Discovery Software.
Hackit ROM
JL-Copy Utilities COPY Utilities v2
Disc'O'Magic v4.1

Games:
--------
ChibiAkumas Episode 2

Demo:
---------
Onescreen Colonies #2 patched for CRTC 3

[zhulien]

Pyradev is debatably the best old assembler suite for CPC, Maxam 1.5 is pretty good too for a 16kb ROM.  Both are now well out of date when compared to modern assemblers.  Still, if I could patch Pyradev to work properly on an M4, the monitor is excellent. 

[eto]

Based on all the comments I would draw this conclusion:

• +64K: for 464/664 highly recommended to get access to most of the applications and all 128K games
• +256K: some applications will benefit a lot
• +512K: SymbOS becomes fun, few applications will benefit more
• +1/2/4MB: no killer app (yet), but will be your choice, if you produce your own new content that takes advantage of the RAM

I guess I'll skip the idea of adding a 4MB SIMM to the CPC.

[TotO]

2x256K for a DRAM. 1x 512K for a SRAM. (allows 512K or 256K + 256K drive from BASIC & CP/M)
In both cases, the base address is the CPC standard &7Fxx. That is compatible with everything.

If the idea is to provide an internal upgrade, I like the fact to have 256K for the second bank.
If you would like to support a 1024K SIMM-30 on socket, does the memory refresh is enough fast?

[eto]

2x256K for a DRAM. 1x 512K for a SRAM. (allows 512K or 256K + 256K drive from BASIC & CP/M)
In both cases, the base address is the CPC standard &7Fxx. That is compatible with everything.

If the idea is to provide an internal upgrade, I like the fact to have 256K for the second bank.
If you would like to support a 1024K SIMM-30 on socket, does the memory refresh is enough fast?

I read a couple of specs and it seems the bigger RAM chips need to refresh less often - at least for those specs I found, the refresh cycles grow with the number of rows of their internal matrix. For most RAM chips that matrix is 9x9, 10x10 or 11x11, so we would need 3 additional refresh rows compared to the 8 rows, the CPC already provides. If I continue to use the CRTC lines for refresh and mix them with normal RAM access exactly like the CPC does, I should be able to meet the refresh demands of those RAM chips. 

But it would require lots of soldering inside the CPC - and as much as it tempts me to give it a try just for the sake of it, it's nothing I would see generally as a good idea.

Getting 256KB as the second bank in a 6128 is much easier by replacing the 4164 chips with 41256 chips. They provide the Data IN and OUT pins, use a 8x10 matrix (so no additional refresh row required) and you will only need 3 standard ICs to properly control A8 of the Ram chips. I'll document this as soon as I have finished the prototype and tested it thoroughly. 

But still lots of soldering required, so unless you have to change your RAM anyway because it's fried, I would not do it. 

With all I learned over the last weeks, I think(hope/guess) it should also be possible to produce a simple extension that can be plugged into the CPU socket and only needs 2 lines to the board. With 512KB max, it should be small enough to fit into most CPCs. (Only Plus and 464 cost reduced would need a different PCB).

[TotO]

Sure. About an internal expansion on the CPU socket, I have designed one that use two thin 32K SRAM IC. The idea was to upgrade a 464/664 to be the same base as the 6128. Next, peoples are free to use an external expansion board.

[WacKEDmaN]

ill just throw in my 2c worth....
it would be alot easier to use a single SRAM (512k/1mb) chip, less wiring up/soldering..no refresh circuit needed..

[GUNHED]

ROM and mass storage is no replacement for RAM btw.