i have bought a nms 8245. and it has if correct a memory expansion.
on the board it self.

the seller said it is 128kb extra. i would agree because they have fitted the memory on the standard memory.

if i check the datasheet, what is to be find on the internet.

each chip is 256kb. so multiplay by 4 would be 1mb extra instead of 128, but i am not sure.

i would make a picture, because i would like to have some input about this build in stuff. or sheets etc.


also when i start a game wich needs extra memory i still need to startup with the ctrl key , i assume with extra memory that would not be needed.

The "control hold" on the bootup, makes that the driver B: will not be loaded. So, in that way, you SAVES "BASIC's interpreter free memory space" that is limited to 28815 bytes free (without any diskdrive) in MSX1 and is like 24k free in MSX2.

MSX1 games and some applications, use the until the limit of the BASIC free memory space, if some driver, cart, unit, uses a few bytes of that memory area, the loaders of those games or applications will crash...

In few words, CTRL HOLD has nothing to do with the MAIN RAM size.

Quote:

each chip is 256kb. so multiplay by 4 would be 1mb extra instead of 128, but i am not sure.

You are right to doubt yourself. 464 chip has 64K words, 4 bits in each work, which makes it 32KBytes.

You have eight 464 chips, so you should have 256KBytes of RAM.

If still in doubt, try using mapper test program from tstmap42.pma.

okey 128 more, is also good.

i will search for the tstmap42 file.

i now the function of the ctrl key.
but am i not correct that if i have. 256 kb
and a game does not start in the normal state
and it will start after a ctrl key. that something is wrong with
the addon of the 128 extra?

greetings all info is welcome.

i used the program this is what it says.

mappers found 3-2 64kb

total ram 64kb

what can i assume from this.
that the extra memory is not active?

i also tested a 8245 not modified, and shows 128kb
so the modified nms has less memory then the not modified.

is there some one who has the schema from this kind of build in.

i have not seen this one yet.

greetings

i solved the problem, some hardware fixing,

now it says 256 kb, that looks better.
so i assume i do not need the ctrl key. but i will test that all afcourse

but i still hope some one has a schema from me of this one.

greetings.

To run many disk-based games you have to use CTRL, even if you have 4MB ram.

CTRL on start gives you more base RAM, not the page-switchable ram, ok? If you hold CTRL, you only get buffers for "A:", if you don't, you'll get also buffers for "B:", which eats base ram.

that i did not know.

i always assumed the base ram was expanded, and what was over , was used for other things.

okey thxs.

so all the memory expansion there are for the msx, onboard or on cartridges. is never a expansion of the base ram?

Quote:

that i did not know. i always assumed the base ram was expanded, and what was over , was used for other things. okey thxs. so all the memory expansion there are for the msx, onboard or on cartridges. is never a expansion of the base ram?

Clarification:
The amount of available memory that you see when you start in basic, IS THE MEMORY AVAILABLE for the basic interpreter.
You can get more or less memory by holding CTRL or SHIFT during boot. This kind of memory CANNOT BE INCREASED, because the interpreter is only able to use the higher 32Kb of the memory (The lower 32KB are the ROM BIOS and the interpreter itself) and do not use bank switching to store basic programs.
To access extra memory machine code is usually used.

So, when relaying to the amount of free memory that the MSX-BASIC display there is no difference at all between a machine with only 32KB and a machine with 4MB!

You can add any kind of memory you want, but the memory available from BASIC will not increase more than 28815 bytes.

Is the same for PC's... the amount of extra RAM above the first 640KB (it's what DOS recognise) is managed by programs like EMM, otherwise you cannot access it... Do you understand what I mean?

it was already clear to me by the previous answers.

thnks.

another question about the test program, and the 256kb.

the 256 kb is seen now, i also have a sony expansion memory cartridge 64kb, i can't see this with the test program.

is this because the 256kb is on the same place?
or is the test program not made for that.

sorry for the mabey simple questions, but i have been out of the msx too long.