• Garbage Collector (1)

    09/28/2026 at 03:08 • 0 comments

    Cartridge-based EPROM emulator (32K) for MSX

    This tool was created to facilitate cross-platform software development. Although the original design used an ESP32C3, it did not utilize wireless communication. I spent a great deal of time on this project before identifying a bug in the ESP32C3's USB-CDC mechanism that caused several bytes to be dropped. To this day, the manufacturer has not resolved this issue.

    The original software worked very well—having been tested with an external USB-UART—and offered several features, such as storing the last uploaded ROM, which could also be used for auto-booting.

    Before abandoning the project entirely, I got it working using MicroPython and a fair amount of "vibecoding." I optimized it as much as possible, but performance remains low, and I had to add a display to show the IP address that needs to be accessed.


    Time to move on.

  • Case study for ESP-32_CoCo in a Patola PB-087 enclosure

    07/05/2026 at 23:56 • 0 comments

    I got interested in the ESP32_CP400 project and did a study to see if a version using through-hole components would fit inside a Patola PB-087 enclosure, which measures 96 mm deep, 72 mm wide, and 30 mm high at its thickest part.

    Here is the enclosure:

    For this study, I followed the original project. Although it doesn't include the full schematic, it features board images showing a few more 3.5mm jacks: two for the cassette recorder, one for audio, and one for an RS232 interface. I managed to fit three jacks, but it should be possible to add a fourth one, either by changing the jack type or by removing the power switch to make room for the audio jack next to the VGA connector.

    Original project board:

    Case study:

  • Yamaha YPVS controller schematics

    05/18/2026 at 21:36 • 0 comments

    This schematic diagram was reverse engineered around 2004 from the original modules my brother asked me to fix. I even posted it on some forums, which unfortunately were killed off by WhatsApp groups.

    At the time one of the major challenges was to figure out the internal configuration of the resistor networks which are non-standard types.

    The module is composed by an 8051ish microcontroller, an H-bridge, an ADC, a clipping circuit and a hardware watchdog circuit.