... and also a working FM-PAC and an IDE-CF cart or LPE-MMC cart... just to cover the basic needs of a recently returned MSX user

256KB (inner and faster access) Memory Mapped RAM , 512 KB megaRAM and 3 1/2 720 KB should be fine for most applications or games.

With 512KB RAM it is possible to run things like the demonstration programs that the MSX community released in the past years.

Matsushita Video Graphics probably would require 512KB Memory Mapper.
Philips Video Graphics works with only 64KB RAM, but the animations would require extra Mapped RAM to work.

512KB Memory Mapper and 1024 KB megaRAM would be great! Maybe later, there could be software for 2048 KB memory ...

Graphics or animations would need 256KB or even 512 KB Memory Mapper, for general games and demonstration software even a 512KB megaRAM would do fine!

For 99.9% 512KB is enough... Some people have said that 2MB is better than 4MB because 4MB may cause 8bit overflow on some applications. Anything bigger than 1MB is just for big number freaks and do not currently have practical use.

This is pure speculation, no actual data used... only feelings and about 5 minutes of time:

8KB 2% of software (practically only some old cartridges)
16KB 8% of software (small BASIC programs)
32KB 40% of software (practically all BASIC programs, 97% of cartridges)
64KB 80% of software (minimum for MSX-DOS, Japanese games, cracked 8KB,16KB,32KB cartridges)
128KB 90% of software (Most European games, minimum for MSX-DOS2)
256KB 95% of software (European games from harddisk)
512KB 99.9% of software (New software)
1MB 99.99% of software (New software from harddisk)

I think that most Japanese cartridges only need to use one page of RAM (8/16KB).

MSX1

First 16KB (probably ROM BIOS)
Second and third 16KB pages = game ROM/EPROM
The Last page with 16KB RAM is what the program need .

16+16*2+16=64KB memory

Sure, it is possible to use external 64KB RAM for other purposes. Since a lot of software do not make correct use of bank switch, there is not any need for more than just 8/16KB RAM (the Z80 only see 64KB of memory).
When a personal computer only have 8KB RAM, the memory is rumored to be mirrored into the upper part of the page.

Since the MSX2 has full 64KB RAM and probably more than 64 KB VRAM, it would be more than enough for most cartridges ...

The quick analysis done by NYYRIKKI is very interesting. I haven't found them; but maybe the Generation database allows some kind of detailed queries about such fields (MSX family or RAM needed I mean).

If it's not supported could be a great addition to the database

I'd say in the world of MSX, about 512K is enough for everything! (640K pun intended)

Here is the rationale:

1) The holy grail of all cracked games, translated Metal Gear 2, will work on 256K, but with lots of swaps and no SCC support. On 512K you get fewer swaps and some of the best SCC music (SCC cart with disconnected ROM required in MSX slot).

2) 512K gives a decent size ram disk, if you use Turbo Pascal 3 or something like this.

3) More then 512K is kind of pointless due to general slowness of MSX.

4) Final MSX computer had 512K from factory (TurboR GT).

5) You can upgrade all Panasonic and Sanyo MSX2+ computers from 64K to 512K simply by adding 4 x 44256 DRAM chips. Also it's teoretically possible to add 512K RAM to all S1985-based MSX2 computers.

8KB is enough

Depends on the game and the size of the game on the medium.

For European games, 128kB is enough in all cases except for Micro Mirror Man (which wasn't finished anyways) which required 256kB RAM, and if I remember correctly, Tetris II by RAM also requires 256kB RAM. Unknown Reality also requires 256kB RAM. Don't know if there are any more titles that require more than 128kB RAM. Some games require 256kB RAM if played from HD (e.g. Pumpkin Adventure). So, for legal games 256kB is as much as you really need to run all MSX software.

One of the few application that would require Memory Mapper is GEM. Since for use GEM the software need to have extra (additional) memory to load the 128KB or 256KB games and demonstration from other machines.This even can use 512KB or 1024KB Memory Mapper ...

It is the only thing that I remember that would need more than just 512KB RAM!!!

Well, I'm sure GEM user community is well supplied with memory, both two of them.

Quote:

It is the only thing that I remember that would need more than just 512KB RAM!!!

Don't forget SymbOS, although it doesn't really needs a 1024KB mapper, it could be very useful (specially if you have a standard 128KB machine).

The thing with games is that you can't have oodles o' code at once in memory as your Z80 couldn't cope with it anyway. The smaller the code, the more often the Z80 can run it. In a way it may be the same with maps, if there's some kind of pathfinding involved: the smaller the map, the faster the pathfinding. What's left is the media: music, graphics. If you'd have 2 -big- Moonsound tunes in memory it'd be about 32KB already, add a player, add some frequency tables and the memory piles up. Graphics idem, if you store some anims and/or game graphics bitbusted or pletted in RAM, then this may also pile up quite well. So, media adds to memory usage. Question is: how much media is present in games and how much could be present in games?

In a demo like Sphere the memory equals the amount of frames, where each KB could be like 3..6 frames, so there memory does count.

The minimum specification for MSX2 seems to be like 64KB Main RAM. The graphics are stored into the Video RAM, since it is a dedicated area it should not be a problem for the general applications.The same could be true about sound applications, since even the old Music Module has a small RAM area for samples. Since graphics and sound samples are stored into dedicated RAM chips this does not reflect the real use in the main ram. Even the MSX-DOS2 cartridge from ASCII Corp. has dedicated Memory Mapper (256KB RAM) that would be enough for most applications, a typical European MSX with 128 KB Main RAM plus 128 KB VRAM would be great with the addiction of a DOS2 cartridge with additional 256 KB RAM ... 384 KB Main RAM (Memory Mapper) + 128KB VRAM is enough to play most softwares on the market!

One question that i have is why cracked games like vampire killer had no sound in 128k ram while it had sound effects.What caused the absence of sound?

By experimenting with bluemsx i noticed that there are various strange glitches to find in games that require certain amount of vram.Eg lower vram from 128k to 64 and Metal Gear 2 radar does not work at all,and some glitches appear.

I think though that the official specification of MSX2 machines was 64kbytes of ram,although in theory we could create a machine with fewer than that.

Most Konami games that run from cartridge require no more than 16kbytes of ram,and many only run fine with 8kbytes.

I assume it would be easy to upgrade an msx1 machine to msx2 -(upgrade bios,vdp,diskrom etc)- but not upgrade the ram,wouldn't then be an msx2 machine with fewer than 64kbytes of ram?

Would this be an msx2 machine?