Hi All! The PCBs for the N8VEM 6809 host processor board have arrived. If there are any 6809 fans out there that would like to build and develop a 6809 home brew computer from scratch here is your chance. I am looking for some volunteers to help with some 6809 and Z80 software development.
The N8VEM 6809 host processor plugs into the ECB and the N8VEM SBC is the bus controller and IO processor for the 6809. As a result there is little clutter the memory map for the 6809, maximizing room for any OS or other application. The 6809 has 60K of RAM $0000-$EFFF and 2K reserved for IO at $F000-F7FF and a 2K boot ROM at $F800-$FFFF. The
6809 CPU can interrupt the Z80 or use polling as desired.The design can use 2716, 27C16, 28C16, DS1220 or other 24 pin DIP nonvolatile memories for its boot ROM. In theory you can update EEPROM/NVSRAM in circuit although I prefer straight 2716s during development. The 6809 host processor board includes a small expansion bus with mounting holes for a mezzanine connector if any builder would like to add their own memory or IO.
The only software I presently have running on the 6809 host processor is a modified version of the Motorola minibug debug monitor from their datasheet. Its not much but enough to load programs (S19 format), inspect memory, and the usual debugging stuff.
I'd like to port FLEX, CUBIX, and/or OS-9 to the new 6809 board but at the moment I have other projects underway like the Video Display Unit prototype. The VDU prototype is working and hopefully I get a PCB manufactured before too long. There are photos on the N8VEM wiki if you are interested.
Please contact me by email if you are interested in the N8VEM 6809 host processor board.
Thanks and have a nice day!
Andrew Lynch, 73 de N8VEM
PS, please join us on the N8VEM mailing list and wiki. There are other N8VEM home brew computing PCBs available.