Website update: Zemmix update

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By [D-Tail]

Ascended (8247)

[D-Tail]'s picture

31-03-2004, 08:14

Memory based devices are accessible only in the slot they are inserted in. Most diskdrive interfaces are like that, and the same counts for SCC and ROM mappers. So if you need to give the device some commands, like 'play a note', you first have to switch the correct slot in the correct page.
In the case of SCC and ROM mappers, this is not a problem, because the running program is in the same cartridge, therefor in the same slot. Using the SCC cartridge for SCC Musixx or SCC Blaffer is more annoying, since those programs run in RAM, so must do slot switching all the time.

I/O based devices are accessibly from anywhere, the I/O is a seperate address space with no relations to slot numbers. This is why if you have a Slotexpander with more than 4 slots, slots 5 and higher can only support some kinds of devices. For instance, a Music Module can be used in such a slot, but not SCC.
And, IF you put a Music Module in such an I/O-only slot, the internal program won't run, because it's memory based.

Hmmm.... I should have known that Sad But I was a bit confused with the I/O mapping thing (#FC to #FF). I think that was the whole issue Smile. And the fact I should know all this is because Bitwise (including me) is always demonstrating that network cartridge (I/O-based) and the USB Disk Interface (which actually contains a ROM, so, memory-based).


You can ask yourself why aren't all devices I/O based? The reason why is usually a combination of cost, complexity and practicality. Also, I/O addresses are scarce, there are only 256 accesible in a practical way.

I thought MSX had *more*, because last time in Bussum we had a conversation about that. I.E. the MSX 2+ FS-A1W(S)X had such an extension in order to switch to 6MHz, if I'm not mistaken... Smile

By Argon

Paragon (1119)

Argon's picture

31-03-2004, 09:22

Haha, calm down people 8-)

As soon as I get more info from the Japanese guy, I'll dump them correctly and mention with which emulator I tried them.

Greetings.
K.

By pitpan

Prophet (3138)

pitpan's picture

17-09-2020, 23:08

As I said before, the 80-in-1 works fine mapped as ASCII 8 KB. Super Boy, both Tetris, Double Dragon, both Bouble Bobble versions, and the japanese modified ROMs worked fine as linear ROMs (no mapper at all).

But a I/O mapping, as Guyver said, is quite expensive, and one of the goal of the Zemmix system was to be cheap. I agree that some fine hardware pieces use this system, but I do not believe that it has been used in software titles. Even the SCC uses a normal memory mapper, not a I/O mapping system.

By anonymous

incognito ergo sum (116)

anonymous's picture

31-03-2004, 14:32

pitpan wrote:
But a I/O mapping, as Guyver said, is quite expensive, and one of the goal of the Zemmix system was to be cheap. I agree that some fine hardware pieces use this system, but I do not believe that it has been used in software titles. Even the SCC uses a normal memory mapper, not a I/O mapping system.
Think again.

D-tail wrote:
I thought MSX had *more*, because last time in Bussum we had a conversation about that. I.E. the MSX 2+ FS-A1W(S)X had such an extension in order to switch to 6MHz, if I'm not mistaken...
Correct. There's a relatively unknown feature in MSX2's and up, that's called Switched I/O. The I/O addresses 41h-7Fh are switched via a manufacturers code which must be written to 40h. Ofcourse this makes the I/O even more complex, as the device should only listen to ports 41-7Fh if the correct manufacturer code is written to 40h.

By pitpan

Prophet (3138)

pitpan's picture

31-03-2004, 15:41

Correct. There's a relatively unknown feature in MSX2's and up, that's called Switched I/O. The I/O addresses 41h-7Fh are switched via a manufacturers code which must be written to 40h. Ofcourse this makes the I/O even more complex, as the device should only listen to ports 41-7Fh if the correct manufacturer code is written to 40h.

And the question remains unsolved... Because you are talking about an MSX2 and up feature and all this was about cartridges for MSX1 designed for the Zemmix console. If they are not mapped, why do they do not work? Bad dump or some unknown feature used in Zemmix not fully compatible with MSX.

By anonymous

incognito ergo sum (116)

anonymous's picture

31-03-2004, 16:12

I'm just explaining some I/O stuff to D-tail, you!

If you wanna find out why they don't work, investigate. You have the skills. Don't bug me about it, coz I really don't care.

By pitpan

Prophet (3138)

pitpan's picture

31-03-2004, 16:48

Congratulation for your new title: MSX GURU. Is that 2048 messages?
I hope that when you arrive to 4096 you will get another one: THE KIND MSX GURU Tongue

Regards,

By [D-Tail]

Ascended (8247)

[D-Tail]'s picture

31-03-2004, 17:14

Congratulation for your new title: MSX GURU. Is that 2048 messages?
I hope that when you arrive to 4096 you will get another one: THE KIND MSX GURU Tongue

That's why I'm still called 'MSX Friend' ^^;

By [D-Tail]

Ascended (8247)

[D-Tail]'s picture

31-03-2004, 17:15


Quote:
Congratulation for your new title: MSX GURU. Is that 2048 messages?
I hope that when you arrive to 4096 you will get another one: THE KIND MSX GURU Tongue

That's why I'm still called 'MSX Friend' ^^;[/quote

Darn... It just changed to 'MSX novice' Tongue

By anonymous

incognito ergo sum (116)

anonymous's picture

31-03-2004, 17:33

Congratulation for your new title: MSX GURU. Is that 2048 messages?
I hope that when you arrive to 4096 you will get another one: THE KIND MSX GURU Tongue

I am kind, just not to you.

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