October 9, 2020


The MCX32-SD is an expansion module for the TRS-80 MC-10 and the Matra Alice 4K/32/90.  It adds 32K static RAM, 128K Flash (16 banks, 8K each) and an SD card socket. The SD card interface is managed by an Atmega328P micro controller.


The board is supported by MCX Basic version 3 which is programmed into the Flash memory.  MCX Basic version 3 adds many of the language features found in Extended Color Basic on the Tandy Color Computer (CoCo) along with the I/O commands to manage file storage on the SD card or an Emcee server.

Support for PMODE 3 and 4 graphics modes has been added allowing those with an internal video RAM upgrade to take full advantage.



The SD card interface supports SD and SDHC cards formatted with either the FAT16 or FAT32 file systems. Limited support for long file names (up to 39 ASCII characters) is included.

File types recognized are:

  • Basic programs as ASCII text, C10 emulator files or WAV audio.
  • Machine language (binary files) as C10, WAV or CoCo Binary format.
  • Basic Array files as C10 or WAV.
  • Basic Data files (PRINT#, INPUT#) as ASCII text.
  • PMODE graphics screens as raw data.

Assembly language programmers can utilize a set of BIOS routines to perform general-purpose random access I/O (Open, Close, Alloc, Seek, Read, Write). 


Ed Snider (TheZippsterZone) has designed a 3D-printed enclosure for the board and has agreed to take on the task of manufacturing and sales of the product. Availability is expected sometime before the end of 2020.

Further details and documentation to follow as they become available.