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The CoCo SDC card for the Tandy/Radio Shack Color Computer.

A Second Source for the CoCo SDC

BoysonTech is proud to announce to be another source for the CoCo SDC*.

BoysonTech will begin selling a limited batch of CoCo SDCs starting Monday, June 22nd. Unfortunately, they are sold without cases. The cases available by mid-July.

The CoCO SDC board (without case) manufactured by BoysonTech is priced at $58. The complete SDC unit (available mid July) will sell at $75. 

Cases will come in black (primary), white, blue and purple (special orders).

Now the CoCo Community has two places to buy this must have product:

Richard Lorbieski (BoysonTech)  (website) (eBay store)

Ed Snider (The Zippster Zone) (project page) (store page)

  The CoCo SDC is one of the most sought after upgrade for the Color Computer (CoCo). It has been such a hot commodity that they have appeared on eBay for as much as $200. I contacted Daren Atkinson and obtained permission to manufacture the CoCo SDCs.

  Ed Snider ( has been producing CoCo SDCs for a many years and he makes excellent and quality products. Yet, the demand for CoCo SDCs has sometimes outstripped supply. In the past 2 years, we have seen a huge influx of new CoCo users and unfortunately, these people unknowingly pay these exorbitant eBay prices.

  Moreover, to prevent confusion, I wanted to differentiate my version of my CoCo SDC from Ed’s. It is also a way to prevent unscrupulous people from getting unauthorized warranty repairs/exchanges.

  The solution was to create my version in a different color. I choose ENIG PCBs with matt-black solder mask and gold contacts. Yet, I could only find SDC card modules in blue finish and it looked tacky with the matt-black main board. Thus, I designed the card module from open source schematics.

  As per my agreement with Darren, I pledged NOT to under cut Ed’s prices. In fact, I need to charge a higher price because I use gold plated sockets, connectors and pay eBay listing fees.

From the CoCo SDC manual by Tim Lidner:

     The CoCo SDC is a home-brew project for the TRS80 Color Computer (CoCo). Darren Atkinson began development in 2009. Originally intended to just add floppy disk controller emulation to a Drivewire connection, that idea expanded over time to include emulating a floppy controller for an SD-card reader with Drivewire server access.

     The CoCo SDC aims to solve the compatibility problem by combining the traditional “software hook” approach with a robust emulation of the floppy controller in hardware. This dual mode implementation provides excellent
performance for the majority of software which “plays by the rules” while adding a high degree of compatibility with those titles that employ floppy-based copy protection schemes or simply choose to use their own floppy drivers.

Features and Specifications
• Atmega 328P AVR micro controller @ 10MHz
• Custom 512-byte bootstrap allows firmware to be updated by the CoCo
• 128K In-System-Programmable Flash
• Accepts SD/SDHC cards formatted with FAT16 or FAT32 file system
• Emulates a Tandy Floppy Disk Controller
• Emulate Dragon DOS floppy controllers
• LBA access mode for virtual hard disk support
• Extensions to Disk BASIC in SDC-DOS for disk image manipulation
• Drivewire disk protocol with auto-speed configuration for CoCo 1, 2 or 3
• “Disk Switch” button to support multi-disk programs
• PCB can be mounted in a Tandy FD-502 enclosure

* Darren Atkinson designed and originally produced the CoCo SDC. In 2019, BoysonTech (Richard Lorbieski) obtained permission from Darren to manufacture and sell the CoCo SDC. Ed Snider ( has been the primary producer of CoCo SDC for many years.

The CoCo SDC can be directly purchased from this link: