MSXmakers support

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By RayneX

Resident (44)

RayneX's picture

07-08-2022, 15:08

msxmakers wrote:
RayneX wrote:

Yes, I read through the schematic and a friend told me it was just a voltage divider. It doesn't seem to be relevant to anything with the operation of the MSX Omega in any way though, right? My friend suggested removing the 10k resistor and then replace the 1k resistor with something like 120ohm on the AV line and that would give me all the signals I would need for HDRV as far as I know (keeping Ys disconnected as it's not used as far as I know). Just wanted to see if those two voltage divider lines actually did anything before I basically disable them to pull a good 5v source for the HDRV cable.

Hi, if you need 5v do not take it from a resistor divider because adding the resistor of your device connected to it the voltage will not be 5v anyway.

If you need 5v my suggestion will be you take it from the power source.

If you are going to modify the DIN-8 pin functions just make sure you will never connect a SCART or you will damange your TV.

Thank you for the info. We did figure it out. It did turn out to be the 120 ohm resistor that I replaced the 1k with and it did still impede the voltage enough to affect it. I got 4.97v out of the port with the resistor so we thought we were ok but guess not. So now, the 8pin DIN is modified to work with my Genesis 2 --> 8 pin DIN cable I made to route the signal to the correct pins. I'll post photos and writeup of the MOD and cable when I get the chance so others will know it can work with HDRV cables.

By msxmakers

Champion (473)

msxmakers's picture

08-08-2022, 12:27

RayneX wrote:

Thank you for the info. We did figure it out. It did turn out to be the 120 ohm resistor that I replaced the 1k with and it did still impede the voltage enough to affect it. I got 4.97v out of the port with the resistor so we thought we were ok but guess not. So now, the 8pin DIN is modified to work with my Genesis 2 --> 8 pin DIN cable I made to route the signal to the correct pins. I'll post photos and writeup of the MOD and cable when I get the chance so others will know it can work with HDRV cables.

Hello,
I honestly have no idea what you really mean, maybe now a little more. I also don't know where you posted the photos you mention.
Apparently you are making a cable to connect to the DIN-8 connector and connect some kind of external converter module there (called HDRV, as I understand it).
My suggestion is that you power the external module with its own power supply.
Another thing would be if you intend to include the module inside the Omega casing as I did. In that case, I would directly unsolder the DIN-8 connector from the motherboard.
If you are never going to use the reference voltages of that connector, you do not need any of the 4 resistors, if you do not put them, you will get a point where you can solder a wire with whatever you want to put, be it +5v or whatever you need.
Have a nice day.

By RayneX

Resident (44)

RayneX's picture

08-08-2022, 20:51

msxmakers wrote:
RayneX wrote:

Thank you for the info. We did figure it out. It did turn out to be the 120 ohm resistor that I replaced the 1k with and it did still impede the voltage enough to affect it. I got 4.97v out of the port with the resistor so we thought we were ok but guess not. So now, the 8pin DIN is modified to work with my Genesis 2 --> 8 pin DIN cable I made to route the signal to the correct pins. I'll post photos and writeup of the MOD and cable when I get the chance so others will know it can work with HDRV cables.

Hello,
I honestly have no idea what you really mean, maybe now a little more. I also don't know where you posted the photos you mention.
Apparently you are making a cable to connect to the DIN-8 connector and connect some kind of external converter module there (called HDRV, as I understand it).
My suggestion is that you power the external module with its own power supply.
Another thing would be if you intend to include the module inside the Omega casing as I did. In that case, I would directly unsolder the DIN-8 connector from the motherboard.
If you are never going to use the reference voltages of that connector, you do not need any of the 4 resistors, if you do not put them, you will get a point where you can solder a wire with whatever you want to put, be it +5v or whatever you need.
Have a nice day.

Yeah, it's a converter cable to match the pin out of the Sega Genesis 2 9-pin minidin to the 8 pin DIN of the Omega. HDRV is an acronym for HD Retrovision, a company who makes Component (YPbPr) cables from RGB sources. They are very popular here in the US as SCART is not a standard here. The cable itself requires a 5v source on one of the pins as the genesis standard requires it as well. As for your idea of removing the port entirely, that's not a bad idea. 3DO RGB MOD and Genesis 1 RGB MOD comes to mind as the mini-DIN port would be soldered upside down due to the pinout. At that point it would be an aesthetics decision. I'm working on a few things to see which would be best. I'll follow up when I get the chance. Oh, as for photos, I haven't posted any. I'm saying that I Will post photos when the time comes. Once again, I appreciate all the help you've provided thus far. It's been a long journey to get to this point. Smile

By msxmakers

Champion (473)

msxmakers's picture

30-08-2022, 19:49

protek438 wrote:

Hi,

I finally received a 16 MB CF, onto which I copied the Nextor related stuff and as much games as the capacity allowed.

As you can see from the pictures, my bog standard SVI-738 will load the Sunrise driver and show the CF card. Nextor partitioning tool sees the drive and and can access it. The Basic prompt is the normal one, and not Nextor as in the instructions you linked.

So, hardware side of things seems to be working, but I’m a bit lost with what to do next. Should it load the Nextor Basic in the boot? How can I access the disk from MSX Basic?

I formatted the CF card in Win10 and simply copied the software over. Should I partition and format it using Nextor partitioner.

Hello,
Please, first of all, read these instructions completely from our blog so that you have the most information about partitioning and the differences between msxdos and nextor.
I think we discussed that you had to have 128K to run nextor, so I'm assuming you're already using the system as I programmed it for you with your 128K computer and that works. You have also bought a 16Mb CF card to work with your SVI 738 (64K).

It's a pity that I didn't do very detailed instructions on how to use this card with less than 128K.

The problem is that with 64K of RAM you can't load the MSXDOS v2 Kernel into memory and neither can the Nextor kernel. You can only load msxdos1 or one of its variants.
The system kernel are disk routines that can be accessed as APIs or as commands from BASIC.
That's why it tells you "MSX Disk BASIC v1", it's the maximum it can load and even luckily the kernel has backwards compatibility, when it can't load the newer version it loads an older one.
Unfortunately msxdos1 does not support directories (aka folders) and only supports FAT12 which supposedly limits the disk size to 16Mb. That doesn't mean there can only be one drive per disk, it may support multiple disk partitions, but I don't have all the information.
After analyzing your images, it is possible that the only thing you need is to copy the files of the msxdos1 version, these are:
command.com
msxdos.sys
If these files are already copied, the problem must be that it does not recognize the format of the partition, which of course from windows will have been "FAT16" or "FAT32" but not "FAT12".
To do this, I think it is best that you follow the steps in the tutorial to format the disk in nextor mode:
https://msxmakers.design.blog/proyectos/interfaz-msx-ide/instalacion-de-nextor-en-la-msx-ide/

If after formatting the drive and copying the msxdos1 system files the A> prompt still does not appear, you may need to access that compact flash from a LINUX computer and change the partition type from FDISK.
I hope I have helped.

By protek

Expert (121)

protek's picture

30-08-2022, 20:53

Thanks for the info! I’ll check the command.com and msxdos.sys files for MSXDOS1.

By protek

Expert (121)

protek's picture

31-08-2022, 15:29

Partitioning the CF card with Nextor and copying the command.com 1.15 and msxdos.sys 1.03 onto the CF card helped. I’m now greeted with a> prompt and can run dir. Thanks for the help!

I gather that I can’t get subdirectories with MSX1 and the amount of files in one directory is limited, so I need to figure out what I need to run the .rom and .lzh files.

By msxmakers

Champion (473)

msxmakers's picture

01-09-2022, 11:55

protek wrote:

Partitioning the CF card with Nextor and copying the command.com 1.15 and msxdos.sys 1.03 onto the CF card helped. I’m now greeted with a> prompt and can run dir. Thanks for the help!

I gather that I can’t get subdirectories with MSX1 and the amount of files in one directory is limited, so I need to figure out what I need to run the .rom and .lzh files.

I think your limit will be only the available space.
Among the various files to download in the link that I have indicated (in the blog), I think that in the nextor utilities there is a command called expand.com or something like that that can help you with the files compressed with LZH.
Not if it's compatible with msxdos1 because I haven't tested it.
To load ROM files there is a utility that usually comes with SOFARUN, I think LOADROM.COM
There has to be at least one version compatible with msxdos1 since it works on the BEERMANIA distribution that exists for the BEER-IDE card, and this one is not compatible with msxdos2 or higher.

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