(WIP) David Haywood's Homepage - 模擬器

By Jacob
at 2017-08-23T20:37

Table of Contents

2017.08.15

"TH Strikes Back is now WORKING"

We picked up 2 more TH Strikes Back PCBs (thanks to Kevin Eshbach for
providing one of them) and dumped the DS5002FP SRAM on each of them.

Using the existing read, and these 2 new reads we were able to apply a ‘
majority wins’ rule on each byte and obtain a correct dump. (about 5 or 6
bytes differed from each board but never the same bytes)

These bytes have all been hand verified, so now I’m confident we now have a
100% good dump of the DS5002FP SRAM for TH Strikes Back (Thunder Hoop 2) as a
result the game works fine in MAME (aside from some video priority glitches
on the title screen but these are unrelated to the protection)

Note, we still need another PROTECTED (not converted to de-suicide ROMS)
Alligator Hunt to verify the dump we did of that before releasing it and at
least one additional Target Hits (we only have 1 copy) before we can
confidently release that also. It’s fairly clear at this point that random
bytes get corrupted during the process, so without multiple copies to dump we
can’t trust the data.

Also the call still goes out for anybody with a working Play 2000, ideally 2
people.

It’s easy enough to tell if you have an Alligator Hunt where the battery
still works as the protected sets will save the Top 2 high scores to the SRAM
so those scores are retained even after powering down the PCB. The desuicide
sets have nowhere to save it so the top 2 scores reset to default when you
power off. We need another working copy of the protected version (ie the one
that saves the top 2 scores)

The other way to identify the protected version is if it shows ‘CHKSUM ROM:
2B34128B’ on startup, these boards are useful to us.

A board that’s already been hacked to not use the battery will show ‘CHKSUM
ROM: F9C6891D’ instead, such boards are useless to us as the SRAM on them is
already dead.

There are no known unprotected versions of Target Hits or of Play 2000, so if
you have either of those in working condition we could do with them.

We currently have a number of Glass boards, and hopefully 2 Maniac Square
boards and will tackle those soon.

Please note that once we have reads we’re happy with they can be used to
repair dead boards, but we don’t want to release dumps until we’re
confident about them as there becomes a risk of people trying to repair
boards with bad data, making it more difficult to obtain the PCBs we need to
verify it.

Here’s a video of TH Strikes Back
https://www.youtube.com/watch?v=qVr2LQTbn_E