Future Spy, any ideas ?.

[cliff_poole]

The first thing I had to do was repair several damaged tracks and replace some capacitors that had been broken off.

Next, I replaced the 10125 chip in the clock circuit, the clock was going in but not coming back out.

With the clock restored, the game just sits in a crashed state (there is no watchdog), i did a quick check of all the control lines, address and data busses. The ROMs read and ID'ed OK when removed. I then plugged in the Fluke and tested the program RAM as well as all the other RAM and the bus test, all OK.

I wasn't getting anywhere so dug out my working Zaxxon, the hardware is pretty much identical. With the FS bottom board plugged in to the Zax top board, the game runs but with completely screwed graphics as you'd imagine. I then tried the three Zax program ROMs in the FS top board (with the FS bottom board), again, the game runs, all screwy but it is running.

This is where I am stuck at the moment. Unfortunately I don't have any of the weird TI 2564 EPROMS spare so can't just try a new set. My next step was going to be to read some data from each ROM in turn in a loop using the Fluke.

Does anyone who is familiar with the code know if Future Spy addresses any bit of the harware that Zaxxon doesn't ?.

 

[DanP]

Doesn't Future Spy have some security block or IC on it?

 

[cliff_poole]

Hmmm. There is no block but there are two bipolar PROMs. I know that one of these is the colour PROM, the other I'm not sure about. It is definately worth a look, thanks.

 

[DanP]

Found a pic of a FS board. See the block in the top right next to the 3 eproms;

http://www.tvspels-nostalgi.com/Bilder/PCB/futurespy_pcb1.jpg

Pretty sure it wont work without it.

Dan

 

[Mitchell Gant]

Found a pic of a FS board. See the block in the top right next to the 3 eproms;

http://www.tvspels-nostalgi.com/Bilder/PCB/futurespy_pcb1.jpg

Pretty sure it wont work without it.

Dan

Crikey! Look at all that typically Sega analogue sound circuitry, there's loads of it!

Wonder why they liked analogue sound so much, reminds me of Buck Rogers and Astron Belt boards that I used to have, they were full of op-amp oscillators too.

Maybe they employed an analogue designer and had to find him something to do.

I suppose at least they didn't sound like Atari POKEYs or other sound chips of the time.

 

[cliff_poole]

Arrrgg !. That explains everything, thank you so much

. I dread to think how much more time I'd have wasted if you hadn't pointed that out.

Mine came with the CPU missing so I just put a normal Z80 in there. My Zaxxon and Congo Bongo both have straight Z80s.

I'll add a note to my database, put it back on the shelf and move on.

 

[cliff_poole]

The sound is the thing I like most about Zaxxon

.

Is it just my imagination or did they use Zaxxon sound effects in Blake's 7 laser battles ?.

 

[DanP]

Just a thought, might be worth trying some Zaxxon roms in there with a regular z80. Never know it might just work

Dan

 

[cliff_poole]

I strongly suspect it would run as Zaxxon, problem is I already have Zaxxon. I'm going to hang on to it just in case someone unearths a bootleg at some point.