SD-Cart JR: An MMC/SD card reader cartridge

[raphnet]

A new version (v04) of the SD-Cart JR software is available!

Mostly compatibility improvements and small fixes:

• sdpart.com / sdcart.sys : Add retries reading MBR (fixes some non-working cards)
• sdcart.sys : Use CMD13 (Send Status) instead of CMD10 (Read CID) to detect card changes (Solves occasional errors with some cards)
• sdpart.com : Add more error checking, display card info before reading the MBR, so at least some info is displayed if the read fails.
• BIOS : When reading a sector fails, it is retried at least once. (Fixes issues with some cards where drive C: would not be available)

Available for download here: https://www.raphnet.net/electronique/sdcartJR/index_en.php#3

That worked! Kinda. Once. sdpart.com worked once when I used it right after booting up. But if I try it a second time (even immediately) it fails again. Rebooted and tried again and it didn't work.

I bought exactly the same model of card you have, and I reproduced and corrected / worked around the problem. Please let me know if you get the chance to test the release above. Your card should work now.

I also uploaded STL files for 3D-printing an enclosure which has a slot and other minor modifications built in. I do not have access to a 3D printer right now, so it's not tested yet. I ordered prints which I'll receive in 1 or 2 weeks...




STL files can be downloaded here: https://www.raphnet.net/electronique/sdcartJR/index_en.php#8

[Fenyx4]

I bought exactly the same model of card you have, and I reproduced and corrected / worked around the problem. Please let me know if you get the chance to test the release above. Your card should work now.

I also uploaded STL files for 3D-printing an enclosure which has a slot and other minor modifications built in. I do not have access to a 3D printer right now, so it's not tested yet. I ordered prints which I'll receive in 1 or 2 weeks...




STL files can be downloaded here: https://www.raphnet.net/electronique/sdcartJR/index_en.php#8

My Transcend cards work now! Thank you. You rock!

And I look forwards to trying this stl file out. But also don't have a 3d printer.

[Brutman]

Well, that was hilariously good fun.

I wanted to get up and running as quickly as possible so I just used the device driver. SDPART worked fine and was happy with my card, a relatively recent 32GB Sandisk. But for the life of me I couldn't figure out why I couldn't get a drive letter ... until I remembered that I was running DOS 3.3 and FAT16 no workie there. Rebooting to DOS 5 cleared that up.

I cheated on the installation as I did not want to go through all of the steps with DOSBox. First I partitioned using SDPART but that only created a 24MB partition. (I was expecting 32MB.) I used Linux fdisk instead to create a 200MB partition, formatted it with mkfs.msdos and then put it back in the machine. Something was cached because chkdsk was showing a file that should have been blown away and the old partition size, so I rebooted. After that I ran chkdsk and I had a 200MB partition. From that point on SDCART detected card changes, but I don't know why it missed that first one.

I have my own IOTEST program written for XTIDE and JRIDE testing almost a decade ago. Same exact executable name. ;-0 Mind reports about 40KB/sec for writes and 50KB/sec for reads. A jrIDE with spinning rust is reporting around 300KB/sec for reads and 150KB/sec for writes, and that drive is a bit fragmented so it might be faster, but close enough. I suspect there is some room to improve things, especially on the read side.

I have two suggestions so far:

• Provide simpler instructions for SDCART users that just use Linux fdisk and mkfs.msdos.
• On the patching DOS 5 instructions on your site - you might want to point directly at http://www.brutman.com/PCjr/docs/Patchi ... e_PCjr.pdf . I think that's much better than making everybody slog through the old forum thread.

Well done! I want to try out the boot ROM next, but that's going to be a bit more involved.

[cyb2600]

Hi,

I'm trying to use one of these carts with a Japanese IBM JX. It seems like others have made it work with the New Zealand version of this machine but I'm running into problems.

I wrote the BIOS to EPROM. When I boot in "PC Jr" mode I get the "13h installed etc" message. But I can't boot from the SD card. If I boot off floppy I can't access the C drive either unless I install SDCART.SYS. With that installed it works fine

In JX mode I don't get any bootup message from the SD Cart. When I boot from JX DOS SDpart.com works. But if I put SDCART.SYS in the config.sys, the computer freezes.

Ultimately I'd like to be able to boot off the hard drive and use it in both JR and JX modes. Has anybody had any success with that?

[Brutman]

When you are in Jr mode ...

With the BIOS support the machine should be able to boot any version of DOS from the SDcard. The SDCard has to have a valid MBR and the DOS partition must be marked as "ACTIVE." DOS 5 and up need to be patched too. Can you verify all of this is correct? You should be able to do that by booting the same DOS version from floppy disk, and then using fdisk.

[cyb2600]

Yup, I tried with DOS 3.3 and DOS 5 patched via the dos box instructions. When I boot from floppy FDISK tells me it can’t find any hard drives even though I can access it just fine. If I boot from floppy it can’t see the hard drive at all unless I load sdcart.sys first, but even then FDISK doesn’t see it.

[jscrow]

If you get the chance, could you confirm if the DOS 5.0 fdisk /mbr command alone fixed it? I plan to write a few paragraphs about booting and related troubleshooting, and I would like to mention fdisk /MBR as an alternative to the sdpart "c" and "w" commands, but I'd like to be sure it actually works.

Yes that worked! I booted from a patched DOS 5 disk, ran fdisk /mbr, then fdisk again (to set active partition), then format /s and it now boots to DOS 5!

I formatted using a previously patched version of format.com, otherwise after format /s, I would have had to patch DOS 5 for the PCjr the old fashion way ...