MSX2+ vs Zemmix, any real difference?

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Door DarkSchneider

Paladin (862)

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14-07-2019, 10:29

I'd like to know if there is any real difference between a real MSX2+ computer and Zemmix. Has anybody detected any issue on behavior of something to fix?

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Van alexito

Hero (536)

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14-07-2019, 11:44

Hi,DarkSchneider. I have a Zemmix Neo for at least 4 years. I can assure is just like other MSX Computer but with more goods than bad things.

The Bad things:
- poor audio output.
- Cartridges Slots incompatibility with NMS-1205,Tecnobytes Slot Expander, MidiPac2
- Find the right PS2 Keyboard is hard to get it in now days my is a Gateway Model SK-9920 I think it was tested to work correctly after testing 3 or 4 different brands.

The Good Things:
- MSX2+ Compatibility is very close mostly all the time.
- Turbo Speed with Z80 running at 10 mhz
- Did you know Zemmix Neo have a extended Video Ram of 1024KB, well is true just try KdL OCM Firmwares and play with this awesome feature not exploited at the moment.
- Compatibility with some modern Hardware Interfaces greatly improve your MSX experience GR8NET,Franky,Playsoniq,MidiPAC

Well, this is my humble opinion and waiting for other Zemmix/OCM users reporting more experiences so we can know the bad and good things about this new way to enjoy our favorite computer.

Smile

P.S: You can see some examples just watching my Technical Videos from Youtube

Van Grauw

Ascended (8398)

afbeelding van Grauw

14-07-2019, 12:03

The 1chipMSX / Zemmix Neo is an emulation in FPGA and the emulation is not perfect, so as a programmer this is sometimes I run into sometimes. E.g. in with VGMPlay I encounted an issue with line interrupts on line 208, and with my RPG project I encountered an overscan issue. KdL has been very helpful fixing those issues, but still… It’s good to keep it in mind.

In other words, don’t use the 1chipMSX or Zemmix Neo to do development on or verify real machine behaviour, it is better to use an accurate emulator like openMSX and a real machine. And when you encounter an issue on the Zemmix Neo, report it to KdL.

Van alexito

Hero (536)

afbeelding van alexito

14-07-2019, 12:13

@Grauw Wrote: "In other words, don’t use the 1chipMSX or Zemmix Neo to do development on or verify real machine behaviour, it is better to use an accurate emulator like openMSX and a real machine. And when you encounter an issue on the Zemmix Neo, report it to KdL."

100% correct with that statement by that not avoid me to create something unique for Zemmix/OCM users.

Van ducasp

Master (147)

afbeelding van ducasp

14-07-2019, 15:33

I just would like to suggest that you consider a MSX-SM instead of a Zemmix Neo if going through the FPGA route, it has all the perks of Zemmix Neo, some of the disadvantages were fixed, FPGA is almost twice the size of OCM/Zemmix Neo so it has more stuff being done to it (WiFi interface, extra sound chips, built in midi) and has way better 12V/-12V supply that fixes some cartridges that do not work (and its base firmware is KDL OCM, so you start with a pretty good base that is the same as Zemmix and jus has new stuff being added to it :-)), better sound and HDMI output. It sounds like MSX-SM should be more expensive than Zemmix/OCM, but it is not.

P.s.:it is not an advertising on any way, I don't earn a single penny on MSX-SM sales, I'm just a happy owner of a prototype and develop some stuff for it (unapi/WiFi) absolutely for free.

Van DarkSchneider

Paladin (862)

afbeelding van DarkSchneider

15-07-2019, 09:46

Grauw wrote:

The 1chipMSX / Zemmix Neo is an emulation in FPGA and the emulation is not perfect, so as a programmer this is sometimes I run into sometimes. E.g. in with VGMPlay I encounted an issue with line interrupts on line 208, and with my RPG project I encountered an overscan issue. KdL has been very helpful fixing those issues, but still… It’s good to keep it in mind.

In other words, don’t use the 1chipMSX or Zemmix Neo to do development on or verify real machine behaviour, it is better to use an accurate emulator like openMSX and a real machine. And when you encounter an issue on the Zemmix Neo, report it to KdL.

https://bitbucket.org/grauw/vgmplay-msx/issues/1/music-plays-too-slow-on-zemmix-neo-ocm
It was solved on Zemmix firmware?

It is a shame as the idea was to exchange the computer by the Zemmix, as it is easier to handle and use for me. Can use it from the seat with the gamepad and a PS2 keyboard at anywhere for games requiring it, you can't do it with real MSX.

I usually program strictly for standard, not doing things not mentioned in official documentation, but line interrupt beyong line 208 is standard, because if I am not mistaken, if you scroll up the line interrupts also moves, so you could require to interrupt at line below 208 for something on screen. Or even to program a "timer" every X lines.

About MSX-SM, I already have a Zemmix, and while the program is the same (Kdl firmware) I'll use the Zemmix, it is not worth the change at this moment.

Van Grauw

Ascended (8398)

afbeelding van Grauw

15-07-2019, 14:26

Yeah, I had made a workaround for it before, but I was able to remove it because KdL fixed the underlying issue.

DarkSchneider wrote:

I usually program strictly for standard, not doing things not mentioned in official documentation, but line interrupt beyong line 208 is standard, because if I am not mistaken, if you scroll up the line interrupts also moves, so you could require to interrupt at line below 208 for something on screen. Or even to program a "timer" every X lines.

That really depends on your definition of standard. This particular case was about interrupting on a line that is in the vertical blanking period, regardless of scroll offset. The official documentations neither says that it does or that it does not generate interrupts there (and the reality is somewhere in the middle). In other words, it’s ambiguous, and so are many of the other details around splits and other techniques. The documentation is simply not detailed enough to describe it.

If you limit yourself to only using things that are described, well that is your choice, but it e.g. essentially rules out pretty much all use of line interrupts because the way changes in registers during display are presented (e.g. does it take effect immediately or only on the next line, and can you safely use them during VDP commands?) is not at all described in the manual, it’s impossible to make splits without making assumptions on the VDP behaviour.

In the end it is the responsibility of MSX compatible system developers to provide a proper V9938 emulation. An official MSX3 and later by ASCII could’ve used the V9938 logic source code to provide a completely compatible simulation, however since this is not available to the community, the emulations (be it FPGA or PC) need to be based on reverse-engineering, documentation alone is simply not sufficient to base emulations on like any emulator developer will tell you, too many unspecified details are commonly relied on in practice by software.

Van DarkSchneider

Paladin (862)

afbeelding van DarkSchneider

15-07-2019, 20:59

Well the original OCM ASCII implementation was garbage so not sure about the “quality” for V9938 logic from that source.

Van Grauw

Ascended (8398)

afbeelding van Grauw

15-07-2019, 22:43

Well, I meant more if MSX systems had continued to release after the turboR, with the upgrades being a true ASCII development building and improving on the chips they had at the time.

The OCM implementation was by Tsujikawa from ESE Artist’s Factory, I don’t think they had much support from ASCII in the development, very much doubt they were given access to the original V9938 logic designs etc (that would be wonderful tbh).

Van Manuel

Ascended (15695)

afbeelding van Manuel

15-07-2019, 23:57

AFAIK, Alex Wulms ported the VDP command engine he wrote originally for fMSX to FPGA for the OCM. But, it's a memory. Better ask him yourself if you want to be sure.

Van DarkSchneider

Paladin (862)

afbeelding van DarkSchneider

16-07-2019, 13:27

I am trying to use the RTCSAVE and get UNSUPPORTED KERNEL. How can it be used? No instructions.

SD generated by the sdcreate tool, and booting from SDBIOS. With the Zemmix BIOS I got a "not compatible BIOS" message so the BIOS should be fine.

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