Image of ELF 1802 - Membership Card

ELF 1802 Membership Card

Cosmac Elf Kit
Main Elf Board Complete
  • October 31, 2020 - The Elf Main Board is complete.

Note: Connection for Raspberry Pi 4 using Raspi OS - Adafruit USB/TTL cable - (Pin 1 - G - Black, - Pin 2 - N/C, Pin 3 - N/C, Pin 4 - Green, Pin 5 - White, Pin 6 - N/C). Open terminal window from command line with: screen /dev/ttyUSB0 2400 (This retro computer does not connect well at faster than 2400 baud but your are welcome to try with your setup.

  • November 1, 2020 - Cosmac Elf Complete - No smoke but no lights either. :(
    • Troubleshooting mode.
  • November 2, 2020 - Spent extensive time troubleshooting.
    • I believe the Elf is now operational!
    • I found a number of things to solve the problem.
      • R1 the 10 Meg ohm resistor for the oscillator circuit was open. I knew to check here due to testing prior to installation during assembly. I was measuring about twice the proper value. It must have opened during the installation process. There was no discoloration or any outward sign of damage.
      • Due to the installation of additional memory and an advanced ROM chip, two jumper traces had to be cut. I don't believe I cut one of them deep enough. Additional trace removal seemed to solve that issue.
      • Upon advice from the designer, I had to ensure that pin six on the power in header is grounded. If that pin is not grounded, the Elf is placed in sleep mode. For the time being, I am using a FTDI cable connected to an operational terminal on my RPi to pull it to ground. I will need to find a solution that does not require a computer. I will have to look at the schematic and find a suitable grounding point for that pin.
      • Lee Hart the COSMAC Elf Membership Card developer was very helpful with the troubleshooting.
Complete Elf Computer
  • November 3, 2020 - Complete Elf Computer
Elf Running Adventureland Game
  • Elf running Scott Adam's Adventureland game through a Raspberry Pi 4 virtual terminal.

To be continued: ;)

Page last modified on November 12, 2020, at 09:45 AM