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Me and My Clone incomplete
and abridged
I've been experimenting with digital
electronics for 4 or 5 years now after reading an article in Micro Mart
about Pic micro controllers. I found a diy pic programmer kit in
Maplins and, once I'd soldered it together and got bored with making
it's LED's flash on and off, I started attempting to generate VGA
colour bars on an old PC monitor I had lying about.
After weeks of frustration "why won't it work! the wave on the
simulator is the same as the vga timing diagrams I found on the
Internet!" it suddenly dawned on me, I'd spent ages programming the
pic's interrupts to reproduce the diagrams exactly, but the diagrams
assumed that you knew horizontal sync repeated continuously I didn't
know that so had only generated horizontal sync during the active video
exactly as it was shown on the diagram.
Thats what I enjoy the most, the light bulb moment when you learn
something new.
I then discovered these two websites
Chris Smith's
website
and
Parallax propeller
I invested in a propeller chip and a programming cable and after a
while got the pc
monitor to display spectrum .scr files.
Then I got some z80's from ebay, some 32k sram chips and started to
breadboard a spectrum clone (I took the easier route with sram, no
contention
and no floating buss)
If I clocked it really slowly (less than 1Mhz) with the spectrum rom
loaded into the
sram it would almost initialize "sometimes". I guessed it was noise
from
the breadboard. So back to the net for more research. I discovered the
concept of the ground plane and dead
bug construction!
resulting in this mess:
Which, suprisingly, worked! It loaded and ran Atic Atac and other
games...for a
while.
After a long fruitless search for what was causing a less and less intermittent fault, I consolidated what I had
already onto a new board and changed the video output from VGA to a 7"
LCD screen I salvaged from a cheap digital photo frame.
This worked for longer before developing a similar intermittent fault.
A final consolidation into la larger CPLD resulted in the final clone
with acrylic case, SD card storage for sna. files, variable clock
speed, mini
kempston/programable joystick,realtime clock, pitch shifter for the
sound and LIon battery pack.
This was working fine up to the point I trod on it and crushed it!!!
oops!
It tried to work after this but the effort released smoke from at least
one component.
I was too depressed to rebuild it straight away, I wanted to improve
the
graphics so thats when I started the Clashbasher project.
Once Clashbasher is working I'll res erect the clone and integrate the
Clashbasher with it.
I think I'll rename it the Pheenix clone.
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