Jump to content

MPU4 ROM carts.


midibob
 Share

Recommended Posts

I've been going demented trying to get a ROM cart to run with a 512K chip in it. I'm using the three ROM type one and using the link settings as per the manual. The cart says it's Ver2.

After a good fair while of swearing and hair ripping out I realised that the socket IC3 which is meant for the 512K chip has address line 15 (pin 1) permanently connected to 5v? Now the version 3 cart has an extra link which looks like it handles this pin but of course that isn't mentioned in the manual as it was probably printed before it was made.

I could easily mod my cart as it's only for testing bizarre faults that don't show on the test rig but I can't help think I'm missing something here being as it's documented in the manual for a 512K chip?

Anyone care to comment......

As an aside the cart runs fine with a 256K chip in IC3, which it would.

Link to comment
Share on other sites

Thanks Tony, might be getting somewhere here.

Hmm the plot thickens! That first pic of the V2 cart looks like it's been modified. My cart is exactly the same number 16539/2 but doesn't have the extra link holes between LK7 and LK5A in fact it's the same as pic 3. Now I can't see from pic 1 but I suspect IC3 has had it's pin cut away from the 5v rail and then goes to that extra link. Both these extra links are marked on the V3.

Could you confirm that for me Tony? Probably a tac wire underneath. In which case the manual is wrong!!!

Link to comment
Share on other sites

8 hours ago, midibob said:

Thanks Tony, might be getting somewhere here.

Hmm the plot thickens! That first pic of the V2 cart looks like it's been modified. My cart is exactly the same number 16539/2 but doesn't have the extra link holes between LK7 and LK5A in fact it's the same as pic 3. Now I can't see from pic 1 but I suspect IC3 has had it's pin cut away from the 5v rail and then goes to that extra link. Both these extra links are marked on the V3.

Could you confirm that for me Tony? Probably a tac wire underneath. In which case the manual is wrong!!!

il check if i still have the card bob if not im pretty sure of where it is i will message him for pictures of back and front 

i do no there was 4 pins between lk7 and l5a and 2 was linked on top 

Edited by stonyat421
Link to comment
Share on other sites

6 minutes ago, midibob said:

That's brill and just what I suspected. The manual is definitely wrong and without that mod these carts won't work with 27512 chips.

Talk about a head scratcher!!:angry:

all fun and games bob 😏but a clever mod

  • Like 1
Link to comment
Share on other sites

OK, done the mod and the games now boot. :clap:

I'm running these on the test rig and unfortunately all I get is garbage on the alpha, ALAA06 on the 7 seg and the alarm. I can see reel activity and I can also throw a couple of the switches which causes a reboot so I assume they are probably the door ones. I have managed to get it into self test as well so it all appears to be running but it won't run the game. I'm using High Rise £6 and I've knocked out the CHR and Checksum checks. Can't find the game manual for this so it's all a bit uphill at present.:headache:

  • Like 1
Link to comment
Share on other sites

27 minutes ago, midibob said:

OK, done the mod and the games now boot. :clap:

I'm running these on the test rig and unfortunately all I get is garbage on the alpha, ALAA06 on the 7 seg and the alarm. I can see reel activity and I can also throw a couple of the switches which causes a reboot so I assume they are probably the door ones. I have managed to get it into self test as well so it all appears to be running but it won't run the game. I'm using High Rise £6 and I've knocked out the CHR and Checksum checks. Can't find the game manual for this so it's all a bit uphill at present.:headache:

pm mate you could run it in the emulator may shed some light on it 

Link to comment
Share on other sites

I've now managed to get the games running but it's been an uphill struggle. My main issue has been the test rig as the game software is quite fussy what it sees on certain switch ports. Also not having a proper reel deck caused loads of alarms till I worked out that on boot up it needs all photo sensors to be open and then all closed to run the game.:headache:

The problem with the alpha must be a timing issue as I'm using a modern OKI printer one. This works fine with the diags but not with game software. Very occaisionally it will actually show proper text so I'll just ignore it for now.

I also had to close 4 of the aux switches as these I know now are the coin inputs from the mech.

My usual adage of 'I won't be beaten' has paid off yet again. I think it's put years on me though, I must be about 200 by now!:lol:

  • Like 2
  • Haha 3
Link to comment
Share on other sites

 Share

×
×
  • Create New...