Blkdog7 pays a visit

John Jacobsen (aka blkdog7) stopped by for some parts the other day and we fired up the PPClone for a sec to show the status.

Skip over to 1h 18m 02s to see the clip.

Test Screen Hurdle Success!

Finally got through that test screen hurdle. A lot of 06xx and 5xxx custom stuff to figure out. In the end I decided it was worth the time to just work though the disassembled Z80 and document everything. I figured out about 80% of it all. It was actually pretty fun.. I haven't had to do so assembly since college.  ;)

That allowed me to pinpoint exactly where I was running into trouble.

Then I ran into some Z8002 instructions my core didn't support yet so I put in a simple workaround until I can get that stuff implemented.

I also wrote up an arcade video to LCD interface so I can work on the design without needing that arcade monitor.

Long story short... I'd say we're making some headway:

Crazy characters

Just a quick status. Lots going on these days with work, board repair, and now a new job prospect. Crrrrrazy!

Barely had time to shoot this video:   

Time to call in the Austrians

So it looks like the Z80 and both Z8002's initialize and pass all memory checks and the Z80 is at the point in the code where it is looking for some status from the 06xx. Now the 06xx is basically a customs controller and it has the ability to control up to 4 separate Namco 5XXX series devices.  As it stands.. Pole Position actually has 4 of these: 51xx, 52xx, 53xx and a 54xx
So this means I have to now reverse engineer 5 more Namco customs. Or do I?

Calling in a favor from my buddy Wolfgang, who has been working in parallel on an FPGA implementation of the Galaga system.  He and I have been sharing the code for our customs for a while and I'm happy to see that he has already done quite a bit of this work:
http://www.pin4.at/pro_custom.php

Woot!

"ERROR IC25"

So the design as it stands today is sitting in the FPGA but alas.. it doesn't seem to be executing the same as the original hardware. As I dug further... I spotted some memory location reads that didn't line up. Turns out.. those are to the security ROM located at 4K for Pole Position 2 which of course, doesn't exist in my design.   (Duh!)

I know there are hacked romsets out there that bypass it (replace jump instructions with NOPs), but I'd rather handle it in hardware. That way, when people ultimately use this thing, they can just grab authentic PP and PP2 romsets off the web, toss it on here and it will just plain work.  Rather than spend too much time on this just yet, I've decided to switch to the PP romset for FPGA implementation. Once that's all set I'll reverse engineer the IC25 for PP2 and re-veify that PP2 works as well.

09xx cracked!

Fwew.. what a pain. That larger CPLD had tons of space but due to those longer wires there was quite a bit of noise that made it tricky to clean up.  After weeks of working on this guy I was finally able to get it working.

That's it for the CPU/Video related customs which means I can start preparing the RTL for the FPGA development platform. Stay tuned for those updates.. I hope to start a video series that captures the progress from here on out.

June 2012 Status...

Making a lot of headway on the hardware design.  I have all of the CPU and Video PCB logic coded up in verilog (with the exception of the sound stuff) and simulating. The Z80 and Z8002's are working (in simulation....so far) but its becoming apparent to me that I'm gonna have to toss this thing into a devkit soon to iron out the bugs. It literally takes hours of simulation time just to get the system out of reset, which happens in a matter of seconds on the actual hardware.

On another note I've started work on the 09xx series custom. I tried programming it into my FpgaArcade device but alas.. it was too small. Time to bring out the big gunz!