Dragon Shared Memory

Board for share data and/or programs between a PC and Dragon Computer throw expansion bus.

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The aim of this project is design a board for share data and/or programs between a PC and Dragon Computer throw expansion bus. Using a 2K x 16 Dual-Port SRAM chip attatched to Dragon computer expansion bus and attatched to external AVR microcontroller for interact from PC and read or write data/programs to Dragon.

Other purposes can reach a development card used for test programs developed with 6809 compiler directly to read hardware same as Dragon 32/64.


This is project first version and its divided into two cards.

Dragon Memory Card

This card contains a Dual Port SDRAM Chip connected directly to Dragon Computer expansion bus. And can accessed directy from Dragon Computer from address $C000. 

USB Data Transferd Card

This card contains ATMEGA8515 microcontroller and Latch 74HC573 for attach DP-SRAM as a external microcontroller RAM. 


Eagle format schematics. Without PCB.

RAR Archive - 311.06 kB - 08/31/2017 at 12:29


  • 1 × IDT 7133SA 2K x 16 DUAL-PORT SRAM
  • 1 × ATMEGA8515L Microprocessors, Microcontrollers, DSPs / ARM, RISC-Based Microcontrollers
  • 2 × 74HC00 Electronic Components / Misc. Electronic Components
  • 1 × 74HC573 Electronic Components / Misc. Electronic Components
  • 1 × FTDI USB-TO-TTL Serial converter

View all 7 components

  • Make better use of memory space

    Tomeu Capó09/02/2017 at 18:50 0 comments

    Improve memory addresses

    Make better use of the address space to increase the capacity of the solution. We currently only use the lower bytes of each memory location.

    IDT SRAM Chip have 16 bit data bus, and now only use first byte. Can multiplex data on the same chip address but get @13 or @11 for detect change byte for R/W.

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