Powerdrift

[Hurray Banana]

Scores are funny on this one

Need to get 6 golds for a good score (by getting onto the extra track and winning - 5 golds first)

Here's scores:

Course A: 5602466

Course D: 5564342

I'm aiming to do a run of 6 golds on 5 consecutive games on courses A to E, used to be able to do this bitd, best lately has been 4 with a cock up on one of the courses.

Here's a video of the bonus Afterburner plane on course A (also for C and E)

and the Super Hang on bike for course D (hardest course - also get this for course B)

I play on hardest setting (silver car starting in seventh place)

twitch stream

and screenshot of score table

Muerto2014-10-31 15:22:33

 

[Jodo]

I love the way the car morphs into the AB plane and that it's actually playable and not just a gimmick! I had no idea PD did that; thanks for sharing

 

[cmonkey]

Nice driving Eric

 

[Hurray Banana]

Never give up ade

 

[cmonkey]

I've been pondering a high score save mod for Power Drift. It would be quite a technical achievement due to the fact that the high score table is stored in the ram of CPU #1 at run time but the capacitor backed ram is in CPU #2's address space. One solution would be to make a shadow copy of the high score table in CPU #2's ram and update it whenever the high score table in CPU #1's ram is updated. This would mean that a high score save mod without hardware modification to the board would be possible. The other option would be to replace IC55/56 (CPU #1 srams) with NVRAMs. The second option is the easiest from a code alteration point of view but the first is more elegant.

If I get around to doing it (and it's only an 'if' at the moment) then I'd be looking for a tester.....

 

[Hurray Banana]

I'd definitely be up for testing for you ade. sounds a bit tricky.

 

[Hurray Banana]

Is there enough space in the battery backed ram to squeeze the table in

 

[cmonkey]

Yeah, there's tons of room in the capacitor backed ram for the high score table. It's only 400 bytes in size (20 entries x 20 bytes per entry). The high score table is located at 0x1ffa14 in suby address space if you want to have a look at it in the MAME debugger. There are 16384 bytes of capacitor backed ram (2 x 8Kb ultra low power srams) in subx address space ($1fc000-$1fffff).

In theory it should be as simple as creating a flag in the shared memory area and then setting that flag to dirty whenever the high score table is written to. If the flag is dirty then suby copies the high score table to shared ram. subx polls that area of shared ram every vblank for a dirty flag and then copies the high score table to a free area of the capacitor backed ram if it sees one.

There's 64Kb of shared ram so it's just a case of finding an unused 400 bytes within the 64Kb and hijacking it.

Then the boot process need modifying to copy the high score table back to suby address space at boot time.

Like I said, not easy, but doable given time and resource.

It beggars belief why Sega didn't do this in the first place to be honest.

 

[Hurray Banana]

slightly over engineered hardware that doesn't get used by the software guys. seems they made quite a few odd software engineering decisions mid to late 80s.

ade whenever you post i feel like I should of kept up my z80 and 68000 skills going. I'm gonna make a concerted effort to get back on the assembly wagon. I look back at code I wrote in the early 90s and wonder how the hell I wrote it.

 

[cmonkey]

Sometimes I look back at code I wrote last year and wonder what the hell I was thinking so you're defo not alone there!

I'll put this on my radar for next year some time (probably summer), I've got tons of personal projects on at the moment so it'll have to take a back seat for the time being. But rest assured this is definitely something I want to accomplish as I like rising to a good hacking challenge

 

[cosine]

Some fine driving there sir

I wondered what the clunking noise was at first, until I realised you were using the gears to slow down

Need to get one some day, it's one of the few cabs that I really want.

 

[strykr]

Great skills mate, love the AB plane and the Hang on bike

 

[Hurray Banana]

I'll set the camera up so you can see the gear flicks. There sometimes ultra quick

 

[Hurray Banana]

Power Drift practice 5 straight 6 gold runs - started

Trying to do 5 consecutive and sequential 6 gold runs from track A through to E in one play.

Setup two cameras so you can watch me changing gear which is the main way to slow down. sometimes flutter accelerator, never press brake.

Picked up sound from both cameras so drop the volume unless you want to hear the delay and couldn't seem to change the settings for the main camera so it's a bit over exposed. Need to fix this for next runs.

managed two 6 gold runs on A and B but, with a bit of never give up luck.

Also knocked the camera so you can't see what position I'm in after track A

. I tend to move around a lot when playing games standing up

Hurray Banana2015-05-29 15:55:55