A brief note about the TTL to RS232 adaptor I have used to connect the MECB 6850 to my Wyse terminal. The adaptor needs a 5v DC supply, this has been obtained by feeding 5v to the otherwise unused pin 3 of the board connector J3. On my board I feed it through a small 22 ohm resistor soldered on the ...

This is a simplified AIM-65 recreation using a 6522, 6520, and 6532 chips on a prototype board running modified AIM-65 software driving some original parts I'm testing. The machine code monitor is working ok, but not yet the BASIC. Patching the I/O map has been giving me problems and I think the 653...

My 6309 MECB Forth79 system has acquired a new home in a repurposed 19 inch eurocard rack cabinet, complete with Vero 5/24 power supply. I'm using my backplane extension, I shall make some plates to hold the system switches and connectors and maybee a small display too. David IMG_20250330_144226731_...

Thanks, I think I made a bad decision with the installation option choices, I'll try again with a full install next time. I'm using Linux Mint, if all else fails I'll try WIndows 10.

That's good to know Greg, I need to find a programmer for the AVR32EA28 not sure if I have anything suitable. would usb-asp or J-Link work I wonder? I'm struggling with getting the IDE to create a suitable project atm, it needs the appropriate DFP installing before it can continue and the loader fre...

Video showing initial test: https://youtube.com/shorts/Xs-mNs-Hi5g

This uses a hacked PS/2 keyboard receiver which does not wait for successful reset acknowledge sequence to allow operation with MECB keyboard

Ok Greg, happy to oblige. I can try that easily enough on a few systems and let you know what happens. David. Update, the signal lines look ok with pull down to zero whether the 10k pull-up is in circuit or not. master board also has 10k pull-up fitted. I tried hot swapping again and this time it wo...

Now that the AIM65 display is working I have rebuilt the AIM65 rom code to run on my MECB. The changes include I/O space address changes and patching in the SYS_IO PS2 keyboard instead of the AIM65 keyboard. The AIM65 has a bitbang serial port for TTY implemented in the 6522 this is being fed to a T...

Great to see your methodical design process paying of with positive results, looking forward to see more. Its nice to see a led twinkle when the keyboard is initialised by its host though without caps lock it would be of little practical use.

The editor works with minimal modification, I just needed to provide the character input and output functions. sample session: >2000G STARTING ADDRESS? 1000 /0010 The quick brown fox jumps over the lazy dog. /0020 Now is the time for all good men to come to the aid of the party /text The quick brown...