Tag Archives: DUO tiny

ATtiny84 powers this DUO Decimal SBC

Jack Eisenmann has created a number of Atmel-based homebrew computers that we’ve covered on Bits & Pieces, including the DUO tiny, DUO portable and DUO Mega.

Recently, Eisenmann debuted the DUO Decimal, an ATtiny84 based SBC.

“[This] ATTiny84 based computer [features a] 7 segment number display and 2 buttons. [You can] use the 512 bytes of EEPROM to store program code,” Eisenmann explained in a recent project post.

 “[Plus, you can] use the 512 bytes of SRAM for program data and as a code editing buffer.”

Additional key project components include:


(x1) 7 segment number display: LA-401VD (SC56-11EWA)
  • (x2) Button: 101-TS7311T1602-EV
  • (x3) 10K ohm resistor: 291-10K-RC
  • (x1) 20K ohm resistor: 291-20K-RC
  • (x1) 330 ohm resistor (7 isolated): 4114R-1-331LF
  • (x1) 14 pin chip socket: 2-641599-4 (1825093-3)
  • (x2) 3 pin male header: 69190-403
  • (optional) 5 pin female header: 929870-01-05-RA
  • (x1) Larger capacitor: UVR1H100MDD1TA
  • (x1) Battery holder: BAT-HLD-001
  • (x1) Battery: CR2032
  • (x1) Switch: MHSS1104
  • (x1) Board
  • (x1) Fuse for preserving EEPROM between programming cycles

As HackADay’s Adam Fabio points out, Eisenmann designed an entire language for the new board.

“DUO Decimal is programmed in an interpreted language called DUO Decimal Numeric Code (DDNC),” said Fabio.

”There are 47 DDNC commands, covering everything from basic math to list manipulation. Programs can be entered through the buttons, or save your fingertips by downloading them through the AVR ISP interface. The entire C code for the DUO Decimal, including the DDNC interpreter is available on Jack’s website.”

It should also be noted that Eisenmann coded several example DDNC programs, including 6 function calculator with trigonometry, a Mandelbrot set tester and even a version of the classic of the rock-paper-scissors game.

Interested in learning more? You can check out the project’s official page here.

Going 8-bit AVR with the DUO portable computer

Back in 2013, Bits & Pieces got up close and personal with Jack Eisenmann’s multi-core homebrew computer which is built around 16 ATMega328P microcontrollers. However, the talented Eisenmann didn’t stop there, as he subsequently decided to create the DUO tiny, a programmable computer based on Atmel’s ATtiny84.

Earlier this week, Eisenmann debuted the DUO portable, an inexpensive 8-bit computer based on Atmel’s ATMega1284 MCU. The platform is equipped with a black and white LCD output, along with a QWERTY keypad input.

Files are stored in a 64 KB EEPROM chip, with data written and read via a host computer through a serial interface.

All programs on the computer are written in a proprietary language dubbed “DPCL,” an acronym for DUO portable command language. Essentially, 

DPCL consists of plain ASCII commands interpreted by the ATMega1284. The programs are checked for syntax errors during runtime, with 12 KB of RAM allocated for DPCL programs.

Interested in learning more about the 8-bit AVR DUO portable? You can check out the project’s official page here.