8bits4ever SD-512 Not Booting - Help?

Resident (44)

03-08-2019, 23:36

First, new to the forum. Not really an MSX guy, but bought one a little over a year ago, and haven't ever been able to get this thing working, except for one time very briefly. You'll have to forgive me if I'm not familiar with some of the lingo, as I'm pretty much a total noob when it comes to the MSX.

So I have an MSX1, Casio MX-10. I bought this cart about a year to two years ago. I managed to get it to boot into, I believe, Nextor when I first ordered it. I believe it booted into this without an SD card, I didn't have one at the time. But didn't know how to use it. I have not been able to get it to work since (though it has mostly sat on the shelf next to my MSX).

So here is what I'm experiencing: With or without an SD card, when I turn the system on with both switches to the right, it boots into MSX Basic (not disk basic) with 28k of RAM available. So the memory is obviously working. Any other combination of the switches, it just boots into MSX Basic with around 12k of memory.

I tried the two images located in the archives HERE. Neither of them produce a booting system.

I pulled the Flash ROM, and read the code with my GQ-4x4, and while it is similar to the code from the Github(msxsdmapper), it does have many differences. I tried flashing the code from Github into the Flashrom, and it boots to MSX Basic with 12k or 28k depending on whether both switches are to the right or not. I then replaced the ROM with the original code, no change.

I have checked the cartridge slot, it looks nice and shiny, but I cleaned it anyways. No change.

At this point, I'm thinking that it has to be an issue with the CPLD. I contacted Daniel through the 8bits4ever's website, and got about half of my question answered. But he hasn't responded since.

I did some examination, and have mapped out the JTAG pinout on the board, but do not have the JTAG adapter for my GQ-4x4 to try reprogramming the CPLD, although the GQ-4x4 is perfectly capable of programming the XC95144XL. My only other potentially compatible programmer that might be JTAG capable would be my USB Blaster...but I haven't been able to find a confirmation on if it can be used specifically as a JTAG with 3rd party software. So, reading the code from the CPLD is not possible at this time.

I have searched the forum, as well as the web, and haven't seen anything related specifically to this issue with the exception of a few posts on this forum, where uses encountered very similar issues. But the suspected culprit was an issue with a firmware ROM, which the MX-10 doesn't have (just the 32k BASIC 1.0 ROM).

Does anyone have a fix for this issue? I can't help but think this is an issue specifically with the board. It seems from what I can tell that this is an issue with 8bits4ever's redesign. I'm halfway thinking of just ordering a batch of the PCBs from the gerbers on the github, and making my own at this point.... *Queue someone stepping in to talk me out of spending the cash to do that, and offering a solution.

Thanks in advance for the help.

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Par gdx

Enlighted (6422)

04-08-2019, 10:36

Did you proceed like below?

Insert the SD-512 with its SD card in a cartridge slot (when MSX turned off)
Turn on the MSX and enter CALL FDSIK, then make one partition in FAT16 and format it.
Turn off the MSX and copy the files NEXTOR.SYS and COMMAND2.COM
Insert SD card in the SD-512 and turn on the MSX. It should boot under DOS2.

If it works, you can install the following filer and copy your software with your PC.
https://www.msx.org/wiki/SofaRun

If you have a Mac you can use CleanEject to eject the SD card with automatic deletion of hidden files

Par jdgabbard

Resident (44)

04-08-2019, 18:56

I sure did, see picture below. I ended up trying the images in the google drive that were emailed when I bought it back then. Still nothing. It doesn’t look like the ROM is being read. I pulled the ROM and dumped the code. I can always upload that if wanted. But like I mentioned before, the byte comparison with the ROM file on the msxmapper github is different, maybe an older version. But whatever the case, neither rom results in anything new. The only difference I see is when changing from MegaRAM to Mapper. With both switches in the right position I get the 28k of memory.

And to clarify, that is a 16mb card, not a 16gb.

Par Wlcracks

Hero (572)

04-08-2019, 19:28

Mine has non gold plated contacts. I had them cleaned met a glas fibre brush, so the contacts "shine". The unit sometimes didn't boot and a reinsert helped. I guess this unit needs gold plated contacts and maybe pull-up or pull-downs. Maybe the input/output resistance is too high.

Par jdgabbard

Resident (44)

04-08-2019, 20:15

Well, my particular SD-512 has gold contacts on the card edge. I’ve cleaned them, so I doubt that is the issue. Especially since the SRAM is being detected.

Par Pentarou

Hero (551)

04-08-2019, 21:18

I was going to suggest to try the cart on another MSX, before messing further with the ROM and CPLD...
But I suppose if you had the possibility, you'd already tried that.

Do you have other cartridges (to test if the MSX slot/CS signals are working)?
Or any way to load shem (it's a monitor debugger)?

Par jdgabbard

Resident (44)

04-08-2019, 23:09

No, I don’t own any other cartridges. But may go ahead and design on in eagle and etch it to test. Probably be cheaper than ordering and waiting on one from Japan. I checked with some locals I know, and nobody has an MSX (Oklahoma), so there is no way to test.

After thinking about what Wlcracks said, it could be a logic level issue. The MX-10 used an early CPLD for the MSX1 Engine. And it’s technically CMOS, but is supposed to be TTL compliant. I’m wondering if maybe the 29F010 is having problems driving the signals to the High Threshhold. May be worth trying to whack in a resistor network as pull-ups on the data lines.

Par Pentarou

Hero (551)

04-08-2019, 23:39

I used to have the same computer and it was working with an SD-Mapper, so I don't think it's a logic level issue.
Besides, as you wrote, it was working in the beginning. Do you own an O-Scope?

Quote:

But may go ahead and design on in eagle and etch it to test

No need to reinvent the wheel, there are already a few designs like this for example

Par jdgabbard

Resident (44)

04-08-2019, 23:45

Well, by working in the beginning it only booted correctly one time. That certainly could still be a level issue...

Yeah, I have a hantek MSO, and an analog tektronics. Kind of hard to prove around on the cart in the slot though. Guess I could take it out of the shell.

Par gdx

Enlighted (6422)

05-08-2019, 11:17

Have you tried the recovery mode? You should not use another Nextor Rom than the firmware specific for the SD-512. In addition I don't think the program for the CPLD is available. Don't program it with something else.

Your cartridge seems defective. Ask to 8bit4ever if he wants to fix it.

Par Pentarou

Hero (551)

05-08-2019, 11:27

The SD mapper is not the same as the MFR. There's no recovery mode and the firmware and CPLD bitstream are available on the github page, complete with source.