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Author Topic: MSX Computers (Read 4360 times)

Offline TomPhobos

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Re: MSX Computers
« Reply #15 on: 2015.May.16. 00:20:55 »
Here is a description:
http://msx.hansotten.com/index.php?page=msx-2-upgrades
You need a new graphics chip and some standard components. You can get the new graphics chip e.g. at eBay.

Offline lgb

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Re: MSX Computers
« Reply #16 on: 2015.May.22. 10:03:12 »
Is there anyone here familiar with MSX hardware? Since MSX was quite unknown here in Hungary, it's only recently I try to collect information about it, just for fun. I read about the memory paging of MSX, it seems a single byte register (0xA8), with two bits for every of the four 16K "slices" of the 64K address space of the Z80. Nice enough, however this is the point, when I feel lost. On MSX2 it seems there is another, quite Enterprise-128-like solution, ie mapping with four registers, with I/O ports 0xFC,FD,FE,FF (it's similar to EP128, just there it's 0xB0, B1, B2 and B3 ports). Now, my problem: as MSX2 is said to be compatible with MSX, who this new paging scheme is related to the old one, which only known about two bits per 16K slice? It seems there topics are always discussed separately (I tried to find information on the web), but I don't understand how those things related (well I even don't dare to mention too much the "sub slot" [?] topic, but it's another question). If someone can suggest a document about this topic or simply an explanation here, I would be quite happy :) Thanks!

Offline Prodatron

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Re: MSX Computers
« Reply #17 on: 2015.May.25. 21:40:04 »
Have a look here:
http://problemkaputt.de/portar.htm#memory
MSX computers even have a layer above the usual flexible memory mapping known from EP, PCW, NCxxx etc.
First you select...
- a "primary slot" with port #A8
- or even a "secondary slot" (also called sub-slot) at ram address #ffff
...for every of the four 16K page within the 64K visible RAM area.
Selecting the secondary slot is a little bit weird, as you always have to map the primary slot to #c000-#ffff to be able to select its subslots.
Why "slots"? The MSX has 2 external "expansion ports" (like catridges for game consoles) (and 2 internal ones), and each expansion port can be extended by 4 sub-expansion ports. These are the slots/sub-slots.

A memory expansion is placed inside such a (sub)slot. Let's say you have your memory expansion placed in slot 2, subslot 3. If you want to make it visible for the whole 64K you select slot 2, subslot 3 for each of the four 16K pages.
Now you can use port #FC-#FF for selecting the correct 16K page of the memory expansion for each visible 16K page, as #fc-#ff is always the port where the memory expansion of the current slot can be addressed.
In theory this makes it possible to have 4x4x256x16KB of RAM (=64MB) in the MSX :D Slots 0+1 are usually occupied by internal roms etc, so the maximum would be 32MB in practice.

Hope this helped a little bit?

Offline lgb

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Re: MSX Computers
« Reply #18 on: 2015.May.25. 22:28:47 »
Hope this helped a little bit?

Yes, thanks. It seems to be a bit strange, but I can imagine it's because of backward compatibility (on MSX2, with MSX) and similar things.

Offline Prodatron

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Re: MSX Computers
« Reply #19 on: 2015.May.25. 22:33:31 »
Yes, thanks. It seems to be a bit strange, but I can imagine it's because of backward compatibility (on MSX2, with MSX) and similar things.
Even the MSX1 is already able to handle the whole slot system (as subslots are handled by the expansion hardware AFAIK). In theory it would be possible to have an MSX1 running SymbOS with the G9K graphic card and 1MB ram. We never tried it, and the loader will stop when detecting only an MSX1, but it should work.

Offline lgb

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Re: MSX Computers
« Reply #20 on: 2015.May.26. 06:52:04 »
Even the MSX1 is already able to handle the whole slot system (as subslots are handled by the expansion hardware AFAIK). In theory it would be possible to have an MSX1 running SymbOS with the G9K graphic card and 1MB ram. We never tried it, and the loader will stop when detecting only an MSX1, but it should work.

Aha, I see. But even the FC-FF ports are there on MSX 1 too then? Or there you can "only" use this primary/secondary slot system? Or hmm, I should learn more about the exact differences between MSX and MSX2 (and 2+ ...). One thing that I know is the video chip. And I had the suspect that this FC-FF "Enterprise - like" memory paging is an MSX2 specific stuff.
« Last Edit: 2015.May.26. 06:56:03 by lgb »

Offline Zozosoft

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Re: MSX Computers
« Reply #21 on: 2016.November.30. 09:55:45 »
I got a "MSX SD Mapper/Megaram 512K" cartridge for my MSX.
It is possible use it for SymbOS? (SDcard and memory expansion)

Offline Prodatron

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Re: MSX Computers
« Reply #22 on: 2016.November.30. 12:30:46 »
Are you speaking about this one?
https://www.msx.org/news/en/megaflashrom-scc-sd

If yes, it is possible :)
https://www.youtube.com/watch?v=XJ9bBPxA6DE
(starting at 3:33)

There is a driver for the SD reader, and the SymbOS installer will autodetect it (you will see it in the video).
« Last Edit: 2016.November.30. 12:33:48 by Prodatron »

Offline Zozosoft

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Re: MSX Computers
« Reply #23 on: 2016.November.30. 13:03:48 »
Are you speaking about this one?
No, it is another: originaly developed by Fabio Belavenuto, it is open source then now it is produced by various manufacturers.

But I'm not sure about compatibility. If anything say is a "Megaram", then all functionaly compatible? And also for SD interface.

(This is not have a "megarom", but the SRAM can be used for ROM simulation, instead RAM expansion mode)

Offline edoz

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Re: MSX Computers
« Reply #24 on: 2016.November.30. 17:14:53 »
No, it is another: originaly developed by Fabio Belavenuto, it is open source then now it is produced by various manufacturers.

But I'm not sure about compatibility. If anything say is a "Megaram", then all functionaly compatible? And also for SD interface.

(This is not have a "megarom", but the SRAM can be used for ROM simulation, instead RAM expansion mode)

Can you post a picture here? And if you plug it in does it boot MSXDOS? Is there a message during boot?
I'm not sure which device this is..
Have fun with the Z80!

Offline Prodatron

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Re: MSX Computers
« Reply #25 on: 2016.November.30. 17:33:41 »
Ok, I watched some Youtube videos about it, it seems to be something different.
Wow, now I even found the Github project:
https://github.com/fbelavenuto/msxsdmapper/
and it seems, that he already made a SymbOS driver :)
https://github.com/fbelavenuto/msxsdmapper/tree/master/Symbos

I will have a look at it...
« Last Edit: 2016.November.30. 17:37:07 by Prodatron »

Offline Prodatron

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Re: MSX Computers
« Reply #26 on: 2016.November.30. 17:36:39 »
and it seems, that he already made a SymbOS driver :)
https://github.com/fbelavenuto/msxsdmapper/tree/master/Symbos
Hm, unfortunately there is only the original code for the Sunrise IDE interface :(
But with this code...
https://github.com/fbelavenuto/msxsdmapper/blob/master/Driver/driver.asm
...it should be possible to make a SymbOS driver as well.

Offline Zozosoft

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Re: MSX Computers
« Reply #27 on: 2016.November.30. 21:17:14 »
Can you post a picture here? And if you plug it in does it boot MSXDOS? Is there a message during boot?
I'm not sure which device this is..
16701-0
16703-1
16708-2
16710-3
16712-4

The SDcard(s) will be a A: (and B:) drive, floppy drives renamed to B:/C: (or C:/D: if two SD cards used).
« Last Edit: 2016.November.30. 22:06:56 by Zozosoft »

Offline SlashNet

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Re: MSX Computers
« Reply #28 on: 2017.May.15. 08:10:41 »
MSX-DOS has similar easter egg, like at Enterprise:

https://www.youtube.com/watch?v=mtOHc3umVb0

Press ENTER to exit BASIC

Offline JSP

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Re: MSX Computers
« Reply #29 on: 2017.July.02. 21:56:08 »
Hi

Speaking of MSX computers. At about the same time as the EP128 there was a particular MSX1 model, that actually had many of the same specs as the EP128. The Spectravideo 738 had 40/80 character display and assorted graphics modes (only one mode available at any time though). It had a 3 1/2" diskette drive, parallel port, serial port, 2 joystick ports, expansion port, it could do bank switching - and it ran CP/M 2.2. I bought several CP/M based programs for it then like the WordStar package (text, spreadsheet and db) as well as a Hisoft Z80 assembler. The nice thing is that these programs run happily on the Enterprise too as CP/M porgrams, and I currently use the Hisoft package for my assembler coding needs.

The SVI-738 was a kind of hydrid between MSX1 and MSX2, and for this reason it is possible to upgrade it to MSX2 standards. I have kept mine in the original form, since MSX2 machines can be emulated very well and I don't have docs for them anyway.