Tag Archives: DUO Mega

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.

Atmel ATMegas power this homebrew 16-core computer

A talented Maker by the name of Jack Eisenmann has designed a multi-core homebrew computer using 16 ATMega328P microcontrollers.

“The DUO Mega is a multi-core 8-bit computer featuring a robust operating system. The goals of the system are to be efficient, reliable, easy to use, and open source,” Eisenmann explained in an extensive design breakdown posted on OstraCodfiles.com.

“The concepts of this computer should be expandable with more cores, additional memory and alternative processor models.”

According to Eisenmann, each core consists of a single ATMega microcontroller. More specifically, there are actually two types of core: worker and manager (15 worker cores + 1 manager = 16 total cores).

“Cores all share an 8 bit data bus. This data bus sends commands and information between cores. A worker core may not use the data bus unless permitted by the manager core. Each worker core is addressed by an 8 bit identifier,” he continued.

“When the machine starts up, the manager core poles every identifier to find worker cores. Then the manager loads instructions from flash memory into worker cores. The manager core may then behave as an interface for flash read and write operations.”

Eisenmann also noted that the DUO Mega is equipped with a single pool of shared memory in a 32 KB SRAM chip. Meaning, the manager core is responsible for access to shared memory – while also interfacing with peripheral devices.

On the software side, the OS user interface (UI) is based on a stack of windows, with  the DUO Mega supporting color text graphics and windows with 80 by 6 characters. All programs are written in Megaliter bytecode interpreted by the worker cores.

“Each program will run on at least one worker core. The number of worker cores allocated to a program depends on user preference. When the user opens a program, the operating system will first prompt the user for the number of cores to allocate,” said Eisenmann.

“One window will be dedicated to the operating system. This window is called the manager window, and cannot be closed. The manager window displays program information, a clock, files, directories and other useful information.”

Additional information about the Atmel-powered Duo Mega, including a full spec breakdown, can be found here.