|
Unmapped write in Super Locomotive @ $e803
#337218 - 02/25/15 11:59 PM
|
|
|
There's an unmapped write to address $e803 in Super Locomotive. The only values ever written to this address are 0, 1 and $c0 so only bits 0, 6 and 7 are being used. Values of $c0 and 1 are written very early in the boot process (@ $106d). A value of 0 is written at $f65, $1095 and $2f58 and a value of 1 at $10b5 and $2faa.
From a quick play through the game it seems to write a value of 0 when you lose a life and a value of 1 when you finish the bonus scene.
The game seems to play fine with this unmapped memory location so it's probably something minor but does anybody have any clue as to what it might be? Are there any schematics floating around for Super Loco (I've never been able to find any if there are)? Is anybody in MAMEdev lucky enough to own a Super Loco board that could trace what $e803 is mapped to?
$e801 is a control register so I'd imagine $e803 would be something similar, but what is it exactly?
|
|
|
| drewcifer |
|
One bad Mutha-(shut yo' mouth!)
|
|
|
|
|
Reged: 07/01/04
|
|
Posts: 428
|
|
Loc: Sweden
|
|
|
|
Send PM
|
|
|
Re: Unmapped write in Super Locomotive @ $e803
[Re: cmonkey]
#337248 - 02/26/15 09:25 AM
|
|
|
> There's an unmapped write to address $e803 in Super Locomotive.
Good sleuthing! Since Super Locomotive is an early-80s game, these writes may have something to do with "cabinet enhancements" seen more often in the early days of arcades than the later ones. Think of things like lamps (maybe behind a marquee) that may flash when a bonus round is completed, or coin lockout switches once a game starts. Schematics would be best, but if you can find an image of the cab, maybe something will stand out?
Also, Zsolt seems to document some unusual behavior with the video chip (the part about a single bit messing with the palette for red / purple cars) - these bits you've found could also do funny things to a palette chip, so another possibility is looking for unemulated video features on a real board versus what happens in MAME. Bits like these sometimes come in the form of wire-mods on limited-run PCBs as well, so the info may not even be in the schematics.
Unfortunately the rarity of this board makes that tough, but guessing is part of the fun  .
/Andrew
|
|
|
| R. Belmont |
|
Cuckoo for IGAvania
|
|
|
|
|
|
Reged: 09/21/03
|
|
Posts: 9716
|
|
Loc: ECV-197 The Orville
|
|
|
|
Send PM
|
|
|
Re: Unmapped write in Super Locomotive @ $e803
[Re: drewcifer]
#337265 - 02/26/15 05:51 PM
|
|
|
It might be that they go to LEDs present on the development board (but not production ones) as a "code got here" signal too. Sort of a very crude printf debugging
|
|
|
|
Re: Unmapped write in Super Locomotive @ $e803
[Re: R. Belmont]
#337371 - 03/02/15 02:47 AM
|
|
|
Thanks for the replies.
I just noticed that when playing Super Locomotive in 2 player mode (cabinet type = table) that the y-positioning of the sprites is completely wrong when the 2nd player plays (flipped screen). I checked version 0.151 and it was fine but in 0.153 it's broken (and is still broken in 0.159). I don't have a build of 0.152 so I can't tell you whether it got broken in 0.152 or in 0.153.
Here's a snap from 0.151 where the y-pos of the sprites is correct :-
And here's a snap from 0.153 where the y-pos of the sprites is wrong :-
I don't know the correct way to report issues like this so I hope you don't mind me reporting it here.
|
|
|
| B2K24 |
|
MAME @ 15 kHz Sony Trinitron CRT user
|
|
|
|
|
Reged: 10/25/10
|
|
Posts: 2663
|
|
|
|
|
|
Send PM
|
|
|
Re: Unmapped write in Super Locomotive @ $e803
[Re: cmonkey]
#337372 - 03/02/15 03:37 AM
|
|
|
The preferred way to report such issues is registering for a tester account at http://mametesters.org/
However, it's also acceptable to post in this forum for MAME bugs as well.
Thanks for your detailed post. I can confirm the issue happening here on my end as well.
|
|
|
Index 
Threaded 
Unmapped write in Super Locomotive @ $e803
Reply
[Re: 
.
