Geoff Graham's Ascii video terminal - Revised PCB

[gekaufman]

Geoff Graham released an inexpensive video terminal design in 2014. As some may remember I organized a group purchase of PCB's and parts for construction.

Unfortunately the original design only had TTL serial output and it was necessary to add external drivers for RS232 levels.

Several others have updated the firmware including allowing use of a USB keyboard.



Here is an updated PC board that incorporates several changes:
RS232 driver is included (Max232CPE or equivalent)
Color selection is now thru jumpers.
USB connector changed to a USB "A" connector so a keyboard can be directly connected
Barrel Jack input for 5v added
Silk screening improved to show jumper settings.

The original firmware will support a PS/2 keyboard input
David Hansel's modified firmware will support a USB keyboard.

Enjoy!

BTW I have a pile of spare PC boards and can program PIC's for folks. Other parts are very easy to order thru Mouser or Digikey.

https://hackaday.io/project/173216-ascii-video-terminal

 

[Twospruces]

great thread topic!
I have a very hard time with programming the PIC using the MPLAB tool and a PICKIT3. It never boots up. I can't figure out how to go straight from Compiled C code to the PIC.
Any tips?

 

[Twospruces]

Geez, I just made a board version myself to do exactly that - include an RS232 connector.
The original Geoff design claimed to work for TTL and RS-232; did you find that the RS-232 support was faulty? I didn't think one needed teh MAX232 function. The UI allows to invert the data format.
Be good to understand your experience. I use it as a TTL device now but I believe others have certainly used the original design with RS-232 as well.
The Tindie board has improved firmware, and I personally have had trouble with the VT-52 emulation.
I have ported the code as well to support some specific code commands needed for TRS-80 model 100 support.

 

[gekaufman]

great thread topic!
I have a very hard time with programming the PIC using the MPLAB tool and a PICKIT3. It never boots up. I can't figure out how to go straight from Compiled C code to the PIC.
Any tips?

I've just used the compiled .hex files from others, but there's a bit of explanation regarding "bootload" and "programmer" configurations here:

https://github.com/dhansel/TerminalUSB