MSX-C — A new, low-cost MSX Turbo R computer!

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By msxmakers

Champion (360)

msxmakers's picture

14-04-2021, 10:29

As Sergey says, having a RS-232 to USB port adapter does not mean the same as any function of a DE-9 port connected by usb.
I don't know if that helps, but I could easily build a DE-9 joystick USB to MSX adapter that would work with any pc, at least as a joystick, I don't know if that requires a driver in the FPGA or how complicated it would be to implement it.
In my opinion eliminating the DE-9 connectors will not be as interesting a saving as having that port.
Damaging the MSX by connecting another device is not impossible (I think by connecting an Amiga joystick) but it is already well known to all MSX users, if that is the target audience.
You have to see who this product is focused on: someone who never had an msx will not miss an old joystick port but who currently has an msx or recently had it, surely already have joysticks that they want to connect.

If it is finally decided to change the name, my favorites would be MSX-LC and MSX-lite. Although if you finally have V9990, R800 and Moonsound, I would forget the cost by calling it MSX3 +.

I consider that using a driver like the CH376 like the Rookie Drive for MSX is a good choice in many ways, although Konamiman who "doesn't know about hardware" will know more about this than I do.

The most economical approach could be to provide the FPGA with a usb port and if possible, connect through it everything else (keyboard, network, wifi, SD, joystick, mouse, hard disk, floppy drive...). I don't know if this is feasible.

I think that finding an FPGA with a sufficient number of cells to implement the proposed circuit can be the main handicap, and for that ...
Do we have the internal diagrams of those components?
I am talking about a VDP9990 chip and an R800.
If we have these circuits we can estimate the number of cells needed and look for an FPGA with enough capacity, otherwise we can't even decide whether to include or remove them from the list because they might not fit on any available FPGA chip anyway.
If I'm not mistaken, just having the circuitry or doing some hard reverse engineering could we have an implementation of those chips in the FPGA.
What we do have is a Z80 design as a code for FPGAs and therefore I think the cheapest thing is to integrate it and have any speed that the hardware supports.

I hope my comments were helpful.

By msxmakers

Champion (360)

msxmakers's picture

14-04-2021, 11:20

Someone knows if possible to use a V9978 implementation ans so use V9958 and V9990 capabilities in the same video output port?
Until I know when an old MSX computer has V9958 and V9990 has two video outputs that cannot be used in parallel and I don't know if possible joining those video output sources in one.

Otherwise stereo sound output would be an easy to add-on for this project.

By S0urceror

Master (149)

S0urceror's picture

14-04-2021, 11:47

Regarding USB I have quite some experience with the MSX USB drivers for storage, Ethernet and keyboard. This gives you a lot flexibility. And will allow much more if needed.

That being said I agree DB9 connectors should be a standard part of the MSX experience. And not so difficult to make. A couple of lines out of the FPGA with some pull up resistors and maybe a protection diode is all you need.

By DamnedAngel

Master (215)

DamnedAngel's picture

14-04-2021, 12:46

Quote:

Someone knows if possible to use a V9978 implementation ans so use V9958 and V9990 capabilities in the same video output port?
Until I know when an old MSX computer has V9958 and V9990 has two video outputs that cannot be used in parallel and I don't know if possible joining those video output sources in one.

Well, V9958 and V9990 can be and are used in parallel by some applications, so I'd opt for a keyboard key to switch between separated and overlayed. Both configurations have their advantages and it would be a shame not to have any of these options, IMHO.

By JEckert

Rookie (21)

JEckert's picture

14-04-2021, 16:40

Well, I am convinced then that DB9 would be the way to go.
Still, the purpose of the USB ports would be in replacing DB9, and so adding USB for other peripherals will add to the complexity.
Furthermore, I still insist that the computer comes with 2 gamepads, just so the consumer doesn't have to shop for it themselves. Those gamepads will have to be mass-produced when making a whole batch of these computers, but we can worry about that when it comes time to fundraise.

Ultimately, as far as components go, the less chips, the better. We absolutely need Z80, V9958 PSG and MSX-MUSIC to be in one FPGA to make it a viable machine, but I also want WiFi and Ethernet (both to supplant network cartridges and for online updates and downloading games), and internal flash storage for those games (don't see any publisher, whether it is Konami or an indie developer, liking games stored into SD without extra antipiracy steps). If we can get an FPGA to work with these extras, I think we can discuss squeezing more functionality if we have the spare cells for it. At the very least, the test model should act like a bona fide MSX2+ with HDMI, WiFi and secondary storage. That would be a sound foundation.

By JEckert

Rookie (21)

JEckert's picture

14-04-2021, 16:48

msxmakers wrote:

Damaging the MSX by connecting another device is not impossible (I think by connecting an Amiga joystick) but it is already well known to all MSX users, if that is the target audience.

Well for your consideration, the target audience includes players who never owned an MSX because of the high cost of entry. I also want to market this to parents to give their children to, both as a cheap games machine and a tool to learn coding.

By JEckert

Rookie (21)

JEckert's picture

14-04-2021, 16:53

Oh, by the way...
SergeyK, msxmakers, would it be alright if I invite you as collaborators on GitHub? I've worked with you both when I built my Omega, so I feel good with you both adding or changing what I already have put up.

By psxdev

Resident (45)

psxdev's picture

14-04-2021, 20:50

About cartridge, a cheap and universal solution with update support would be great.

@meeso.kim was working in something called Raspberry PI MSX Multipack RPMP based on pi zero. Last hardware revision is from last year but code is older than last hardware revision. Some features:

  • different mappers
  • additional ram
  • multiple rom support
  • audiout signal bus support (not sure about status of this yet based on a dac PT8211 in actual hardware revision )

Other features to investigate :

  • wifi in baremetal with pi zero w. I am testing it with Circle environment
  • full scc option replacement
  • dsk emulation
  • v9990 emulation
  • improve pcb design to fit on different msx models to avoid space problem. A solder less solution too.

It would be great to know status of this by @meeso.kim himself. He has been devoloping different hardware for MSX and i would love to hear his opinion too.

By sd_snatcher

Prophet (3443)

sd_snatcher's picture

15-04-2021, 00:16

konamiman wrote:

Kazuhiko Nishi told me in person that all the MSX firmware ROMs except BASIC (still owned by Microsoft) are free to use. Unfortunately I wasn't able to get a written confirmation, but if this project really moves on then it would be worth trying to contact this man again.

If you do, pretty-pretty-please remember to ask him for the official sources of all other MSX ROMs too, like the mainBIOS, subROM, optROM, MSX-Audio, MSX-Music, MSX-MIDI, MSX-RS232, MSX-Modem, MSX-JE, MSXView etc

By konamiman

Paragon (1117)

konamiman's picture

15-04-2021, 09:28

JEckert wrote:

Well, I am convinced then that DB9 would be the way to go.

Woohoo! You won't regret it. Smile

JEckert wrote:

Still, the purpose of the USB ports would be in replacing DB9, and so adding USB for other peripherals will add to the complexity.

The purpose of the USB ports would be to add expansion capabilities in a modern way ("modern solutions for modern problems", said by yourself) Tongue - think of it as a complement to DB9 ports, rather than a substitute.

About the complexity, just use a separate chip and allow it to be accessed from the Z80, the software will handle everything else.

JEckert wrote:

Furthermore, I still insist that the computer comes with 2 gamepads

Cool. Once the basics are covered, the more extras the better.

JEckert wrote:

We absolutely need Z80, V9958 PSG and MSX-MUSIC to be in one FPGA to make it a viable machine, but I also want WiFi and Ethernet

Agreed. I still think Ethernet is not so vital when having WiFi, but I won't complain about having too much stuff.

JEckert wrote:

and internal flash storage for those games (don't see any publisher, whether it is Konami or an indie developer, liking games stored into SD without extra antipiracy steps).

So you want to exclude SD slot just to disallow piracy? That's a bad idea imho:

1. Pirates will pirate with or without SD slot. They will use a SD/CF/whatever existing storage cartridge, or will use the USB port.
2. Meanwhile you will inconvenience legitimate users who want to have an easy to use storage device to store their own programs, or to update the firmware.

It's the eternal problem of any DRM-style mechanism.

JEckert wrote:

At the very least, the test model should act like a bona fide MSX2+ with HDMI, WiFi and secondary storage. That would be a sound foundation.

Add USB to that and we have the winning combo.

msxmakers wrote:

I consider that using a driver like the CH376 like the Rookie Drive for MSX is a good choice in many ways, although Konamiman who "doesn't know about hardware" will know more about this than I do.

Heh. I meant that I don't know about hardware design, but sure, give me a chip and its datasheet and I can do some neat magic tricks. Hannibal

The CH376 would indeed be a good choice. It's already "battle tested" in MSX (quite poorly documented but we have already figured out all the critical nuances between Xavirompe, Sourceror and me), easy to interface (just a couple of Z80 ports or memory addresses needed), and it's compatible with the CH372 which is a USB device controller - so eventually the MSX could be programmed to act as a USB device.

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