[Coco] The 6-Chip 6809 Computer Saga

[Kip Koon]

Hi All,

Sunday, August 5, 2012, the fiercest Thunderstorm took place where I live in
Manning, SC that I have ever experienced in my entire life.  The storm
ionized a pocket of air in the house about 3 feet tall, 1.5 feet wide and
about 2 feet off the floor with the loudest CRACK I have ever heard!
Needless to say I thought we had lost ALL of our Electronics and computers,
but after careful inspection of everything we own all entertainment
equipment and all computer equipment works fine except one..my main laptop
that I have been doing all my development work on, it won't boot up using
the AC adapter or the battery pack!  I measured to output voltage of the AC
adapter, which is supposed to be 19V, it is actually 16V and since the led
next to the DC input jack on my laptop does not turn on, I'm hoping the
laptop is ok. The reason I say that is the power strip the laptop is plugged
into still works as does the universal power supply that feeds the power
strip.  I still can't figure out how this happened.  I have bought another
ac adapter and as soon as it comes in, I'll see if my laptop still works.
In the meantime, I'm using an old 2GHZ, single core AMD 64-bit processor
based upright desktop computer with 2GB  of ram to continue my development
of my 6809 computer until I can get my laptop running again.  This has
seriously stunted the rate of growth of drawing the schematic for my 6809
computer as I have to recreate all the parts I have been using on my laptop
again on my desktop.  Just in case my laptop is fine, I decided to work on
some upgrades to my 6809 computer.  I have drawn the first version of the
2MB of ram memory expansion addition to my 6809 computer in ExpressPCB.  I
am also drawing the schematic for using 3 memory locations to talk to a big
eprom to hold all programs I might want to use on my 6809 computer.  The way
I'm planning for this to work is having the 6809 boot up with an incredibly
small boot eprom hopefully 256 bytes or smaller that will load the start
menu from this other big eprom by accessing it though means of these 3
memory locations.  That way, I can copy from eprom to ram the 6809 Extended
Basic program, the  Simon6809 monitor program,  some disk extended version
of 6809 Extended Basic using HDBDOS with Drivewire integrated in, and
anything else I dream up.  That way, the eprom can be as big as it needs to
be.  If it grows beyond 64KB, I'll just add another memory location to total
4 locations.  Then it could be as big as 16MB.  In the beginning though, it
will be 2 locations for the address bus going to the eprom and 1 location
for the data bus.  Of course all these schematics are still in the design
stages, but as I earn funds, I will be testing these circuits as well as
others.  I also am planning on replacing the ACIA and MAX232 chips with one
FTDI chip, the FT245R.  For development purposes, I'll be using the UM245R
USB Prototyping Board since the FT245R USB chip is not available in a DIP
package.  This prototyping board has the chip mounted on the board along
with 24-pins or headers that turns the little surface mounted device into a
24-pin DIP package perfect for breadboarding.  I'm going to move the I/O
space to the $FFxx block of memory to allow contiguous ram from $0000 to
$FEFF.  Maybe I can fit the little rom to ram program into some part of the
$FFxx block.  If this all works out, I'll be booting up from this other
eprom and changing my setup to exclusively use USB ports for all my
communications needs.  HDBDOS with Drivewire is a long way off at this
point, but as soon as I have a diskless 6809 HDBDOS DW Extended Basic
running on my little machine, I will definitely let you all know.  I want
this new 6809 HDBDOS DW Extended Basic to support USB ports for a mouse,
printer, and 2 joysticks.  Can you guys think of anything else we can
interface to this little machine?  In my mind, for its small parts count, it
has grown far beyond its meager beginnings.  Grant, thanks so much for the
inspiration!  Until next time, Happy 6809ing!

Kip