Grauw’s blog

1 chip MSX, received!

December 6th, 2006

One chip MSX booting Yes, I received my 1 chip MSX yesterday!

» Pictures on Picasaweb

The OCM is currently an MSX2, I haven’t seen any MSX2+ features. According to the manual, it has a Z80 @3.58MHz (which you can switch to 10MHz with a DIP switch, it does not distort sound) with 1MB RAM, a v9938 with 128kB VRAM and a PSG, OPLL and SCC. It.

The CD that comes with it contains amongst others the VHDL MSX source code for the FPGA. According to the license the code is free for distribution, so I put them up for download here, plus some other things. I didn’t see any ROM files among the source code, so I don’t know where they are stored.

One thing I found is that it does have an RTC implementation, but it does not remember the settings after turning it off (it only does when resetting). Functionality to store the RTC settings to the SD memory card would be useful, or I might try to modify the defaults.

Another problem I encountered is that the text-mode blink colours don’t always work; in TED I’ve seen that the blink colours appeared only after a while (varying from a few seconds to a minute orso), and in Compass they have so far not appeared at all (unless I ran TED before). This is pretty annoying because it is used for e.g. selection bars and so you can’t see what you’re selecting. Fortunately the thing can be updated :).

The VDP debugging functionality has several modes, one showing some kind of timing-signal (if you’ve ever debugged timing by setting the background colour, it looks like that, but on a semi-transparent overlay), another showing the values of the various VDP registers, and others are (I think) showing the alternate screen pages a third highlights sprites and different screenmodes, one indicates on which lines there are screensplits, and finally one shows the screen with the default palette.

If you have questions you can ask them in the comments.

Grauw

13 comments [reply]

Comments

Do you know Henrikku? by Christofer at 2006-12-06 17:39

Hi there!

I’m a KUINEP student from last year who is also a friend of Henrik Lysell, a current KUINEP student from Sweden, whom you might know. He’s extremely poor at updating his blog and me and his other friends at home are planning to mail bomb his Keitai to punish him. If you could find out and tell me his address I’d be very happy ^_^

yoroshiku onegai shimasu m(_ _)m

Christofer Bäcklin
slask@cklin.net

Tests by AR at 2006-12-06 19:17

Hi
are you doing some compatibility tests?
Have you tried to run some rograms or cartridge?
Can you see how accurate is the VDP implementation?
I’m eager to hear about this issue!
bye
AR

by SLotman at 2006-12-06 20:38

Can you recompile the VHDL?
What happens if you change this code on the sprite module:

constant SpMode1_nSprites: integer := 4;
constant SpMode2_nSprites: integer := 8;

with

constant SpMode1_nSprites: integer := 255;
constant SpMode2_nSprites: integer := 255;

? Does the horizontal sprite limit disappear? =)

VDP by PingPong at 2006-12-06 21:07

Hi, have you tested vdp command speed?

Does vdp command speed vary if you overclock the z80?


Does vdp made be faster?

thx

Benchmarks by Ivke at 2006-12-07 09:25

Hi,

I’m very interested in the actual vdp & cpu speed.
Could you do some benchmark testing?

And what about the sound? Did you notice some sound difference between the psg, scc and msx-music implementation and the real sound chips?

Greetzz,
Ivke

Replies by Grauw at 2006-12-07 15:17

Some answers to questions asked…

AR wrote:

are you doing some compatibility tests?

Have you tried to run some rograms or cartridge?

Can you see how accurate is the VDP implementation?

Except for my CF-IDE interface I didn’t bring any cartridges with me, so I don’t have much to test with. Next time I go to Osaka I’ll buy some games :). On my HD I have a couple of games but not many. Bombaman worked great, I tried an old development version of our GuruLogic project and it seemed to work pretty well (there were some glitches, but I think those existed on a real MSX as well). I couldn’t get Pumpkin Adventure 3 or The Lost World to work, they hanged before showing the Sunrise logo (but maybe I need a disk for the copy protection?).

I tried to run some ROM- and disk-images but not many of them worked (Puyo Puyo did and it looked the same as I remember, including flickering glitch in intro screen). However, it’s difficult to say whether that’s caused by crappy FD emulation or the OCM (I don’t think it is the OCM). If I use the built-in MegaSCSI I should probably be more successful, as afaik it has some FD emulation functionality built-in, and I think it also has support for ROM emulation. But anyway, I don’t know how to use that yet.

SLotman wrote:

Can you recompile the VHDL?

What happens if you change this code on the sprite module:

  constant SpMode1_nSprites: integer := 4;
  constant SpMode2_nSprites: integer := 8;

with

  constant SpMode1_nSprites: integer := 255;
  constant SpMode2_nSprites: integer := 255;

? Does the horizontal sprite limit disappear? =)

I have’t gotten into modifying the VHDL at all yet :). I’m a little bit scared of messing about blindly with that, as it could ‘brick’ the OCM and I would need to make a JTAG cable to fix that, never mind that I don’t really know 1. how to make one and 2. how to connect it to my OCM then. Also, my laptop doesn’t have a serial port so I’d need an USB-version, and I don’t know if they’re as easy to make. But, maybe in the future.

PingPong wrote:

Hi, have you tested vdp command speed?

Does vdp command speed vary if you overclock the z80?

Does vdp made be faster?

Testing the VDP speed is a good idea, I’ll do that once I figure out a way to get files from my PC to the OCM (I haven’t set up the SD-card yet).

Ivke wrote:

I’m very interested in the actual vdp & cpu speed.

Could you do some benchmark testing?

And what about the sound? Did you notice some sound difference between the psg, scc and msx-music implementation and the real sound chips?

As for benchmarks, see above. I have done measurements of a ‘normal’ MSX2 in an article on the MSX Assembly Page before, and I should be able to use the same tool.

As for the sound, the PSG sounds great, the SCC I didn’t really have the chance to listen to yet but I would assume it sounds fairly ok too (given that it’s a simple wave form), and MSX-Music is a little difficult to say. But obviously given the non-readable hardware presets the MSX-Music would be the most difficult to ‘get right’. But it’s easy to find what presets were used in the VHDL source code, maybe compare it with the presets emulators use?

Bazix or Japan? by Micha at 2007-04-10 15:06

Hi Grauw,

do you have the 1 chip MSX from Bazix or directly from Japan? I will go to Japan next fall. If you can tell me, where to get it, I can try to find it there somewhere. Or have you ordered directly? How? Or is it the first batch from Bazix?

Thank you.

Best regards from “Zwitserland”.
Micha

sorry by at 2007-04-10 15:26

I just read your previous posting. I’ll try to get one from Japan then.

-Micha

I get one!! by Micha at 2007-04-13 11:02

actually I get one! isn’t that great? the 1chipmsx is already ordered.
(what a luck I have that I have a colleague with a japanese girlfriend ;-) )
but I must wait until june when i really have it ...
a long wait has begun ...

when I got it, I will post my impressions to my blog also.

regards,
micha

Re: I get one!! by Grauw at 2007-04-17 07:55

Cool :). Can you let me know your blog address? Then I’ll keep an eye on it.

one chip msx by mika at 2012-09-17 16:41

hi,

im also looking a one chip msx machine for me too..

But i havent found it yet...

could any one help to me have it ?

Finland ocm MSX to me

Mika

Re: one chip msx by Grauw at 2012-09-19 13:31

Hi Mika,

It’s been a while, I don’t think they’re still on sale. But I’m not the best informed about the status of OCM sales, so maybe I’m wrong. Otherwise you’d need to try and find one second-hand, on eBay for example (also try Japanese eBay).

1 Chip MSX by nawaz at 2013-01-15 13:33

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