The MSX SDMapper lives again!

A few months ago I acquired a Sharp Hotbit MSX computer and it came with another SD Mapper to be added to my collection (I now have three ! 😊). Then, a few weeks ago during tests I’m doing with uMSX OCM, I sourced 9V to the device when should be only 5V.

The OCM has a PPTC fuse that protects it, but those fuses need a few seconds to detect the situation, heat and break the circuit. Unfortunately the time was too much for the poor SD Mapper and it stopped working.

No smoke of death (I know you all love that), but the thing stopped working right away. I almost killed another one by replacing it, but then I figured out the OCM was already turned off and it was saved. 🙂

Opening the cartridge and using the multimeter I figured out I had a short to ground. Following the lines, I noticed the short was right in the first pins of the XILINX XC95144XL CPLD. I don’t have spare XILINX CPLDs in my box as I usually work with Altera versions, and AliExpress will need to give a support here.

Ordered three of those CPLDs (USD 3.42 each) and waited long three weeks to have them here in my workbench.

While waiting for the replacements I had to configure my PC to program Xilinx chips. I do have the Xilinx programmer but I’m not used to ISE or any other Xilinx programming tools. I figured out the latest version of ISE (14.7) needs Oracle VirtualBox and it is a Linux VM with the software (!).

Big package installed I also had to solder programming pins to the cartridge as it came without just to be fitted into the case. I know, did a poor job soldering those ones by it is just temporary. I’ll remove them to put the cartridge back into its case.

After the three weeks waiting I finally got the package from AliExpress with the CPLDs. Well, just two. One was missing a few pins! 😡 Of course I complained and expect to receive my 3 bucks back.

Programmer cable connected to the cartridge and ISE Webpack 14.7 installed (together with the Oracle VM thing). I then cloned the GitHub repository from fbelavenuto/msxsdmapperv2: MSX SD Mapper Interface V2 (github.com)

From the whole ISE Webpack we just need the iMPACT tool. Then I loaded it, detected the programmer and load the CPLD with the JED file that is inside the CPLD folder.

After a few seconds the CPLD is now programmed.

And the cartridge is back to life! Lesson learned, watch out the voltage… stupid. :/

References

• Oracle Virtual Box – Download_Old_Builds_5_2 – Oracle VM VirtualBox
• Xilinx ISE Webpack – ISE WebPACK Design Software (xilinx.com)
• Ali Express XILINX XC95144XL – XC95144XL XC95144XL 10TQG100C new original CPLD chip| | – AliExpress
• Fabio’s GitHub repo for the SD Mapper v2 – fbelavenuto/msxsdmapperv2: MSX SD Mapper Interface V2 (github.com)