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I noticed that quite a few SG-1000 emulators have or had a problem with Safari Hunting - the game freezes when the player enters the playfield ("jungle").

In my little SG1000 emulator I have the same problem and would like to fix it. Currently every game works, even the Dahjee/Jumbo/Aaronix games. Its just Safari hunting that gives me this problem :P

I tried everything I could think of.. tweak irq's, timing, compared my code with other emulators, but just can't find the solution. I was sorta hoping that someone here has gone up against this issue in the past and might be able to guide me in the right direction.

thanks for reading & best regards,
- dink

which emulators you tried?

MESS .142 has the issue, though the current MAME/MESS doesn't.
MEKA before v.40, though it was fixed at .40.
www.play-sc3000.com's sg1000 emulator - http://www.play-sc-3000.com/cart.php?Game=SAFHUNTG&Letter=S
Kega Fusion plays Safari Hunting alright.

To cause the issue, start the game and move your truck to one of the open spots on the field and enter the playfield. If the emulator has the issue, it will freeze up as soon as it draws the player sprite in the field.

best regards,
- dink

I looked at the diff between 0.39 and 0.40 and there's way too many changes to provide a suitable hint. And frankly I had no idea what I was doing back then.

Not sure if you figured the issue yourself by now but some user told me I had the same issue in latest versions of Genesis Plus GX and I found the solution after finding that thread by looking at comments related to that game in Meka sourcecode:

https://github.com/ocornut/meka/blob/0ec668276ad207ec5cf3fecbac3f541a1b07f2a7/me...

Quote

// Fill ROM with 0xFF
// - SG-1000 Safari Hunting : ROM is 16kb, access 48 kb memory map
// (actually there's a correct way to emulate that, see Cgfm2's SC-3000
// documentation, in the meanwhile, filling with 0xFF allow the game to work)

According to SC3000 notes, the correct mapping for that game is the one below:

$0000-$3FFF : ROM
$4000-$7FFF : ROM (mirror)
$8000-$BFFF : RAM (mirrored repeatedly every 2K)
$C000-$FFFF : Work RAM (mirrored repeatedly every 2K)

For some reason, the game is actually reading data from unmapped memory ($8000-$BFFF) which should normally read $FF since the RAM chip is not present. If you return value from a large ROM buffer that was either initialized with zeroes (like I did) or hold data from a previously loaded ROM (not 0xFF), the game will hang.

The mirroring behaviour of games that don't fill the ROM address space is a bit tricky to manage as it's metadata missing from the ROM dumps.

Eke, thank you very much for this info!! I've been wondering this for a long time :D

Author	Message
dink Joined: 09 Dec 2013 Posts: 228 Location: detroit	SG-1000 emu and Safari Hunting Posted: Wed Oct 26, 2016 4:14 am
dink Joined: 09 Dec 2013 Posts: 228 Location: detroit	I noticed that quite a few SG-1000 emulators have or had a problem with Safari Hunting - the game freezes when the player enters the playfield ("jungle"). In my little SG1000 emulator I have the same problem and would like to fix it. Currently every game works, even the Dahjee/Jumbo/Aaronix games. Its just Safari hunting that gives me this problem :P I tried everything I could think of.. tweak irq's, timing, compared my code with other emulators, but just can't find the solution. I was sorta hoping that someone here has gone up against this issue in the past and might be able to guide me in the right direction. thanks for reading & best regards, - dink

nitrofurano Joined: 01 Aug 2012 Posts: 322 Location: Porto, Portugal	Posted: Wed Oct 26, 2016 8:43 pm
	which emulators you tried?

dink Joined: 09 Dec 2013 Posts: 228 Location: detroit	Posted: Thu Oct 27, 2016 12:22 pm
dink Joined: 09 Dec 2013 Posts: 228 Location: detroit	MESS .142 has the issue, though the current MAME/MESS doesn't. MEKA before v.40, though it was fixed at .40. www.play-sc3000.com's sg1000 emulator - http://www.play-sc-3000.com/cart.php?Game=SAFHUNTG&Letter=S Kega Fusion plays Safari Hunting alright. To cause the issue, start the game and move your truck to one of the open spots on the field and enter the playfield. If the emulator has the issue, it will freeze up as soon as it draws the player sprite in the field. best regards, - dink

Bock Site Admin Joined: 08 Jul 2001 Posts: 8651 Location: Paris, France	Posted: Thu Oct 27, 2016 12:55 pm
	I looked at the diff between 0.39 and 0.40 and there's way too many changes to provide a suitable hint. And frankly I had no idea what I was doing back then.

Eke Joined: 06 Feb 2009 Posts: 110 Location: Toulouse, France	Posted: Mon Dec 11, 2017 11:30 am
	Not sure if you figured the issue yourself by now but some user told me I had the same issue in latest versions of Genesis Plus GX and I found the solution after finding that thread by looking at comments related to that game in Meka sourcecode: https://github.com/ocornut/meka/blob/0ec668276ad207ec5cf3fecbac3f541a1b07f2a7/me... Quote // Fill ROM with 0xFF // - SG-1000 Safari Hunting : ROM is 16kb, access 48 kb memory map // (actually there's a correct way to emulate that, see Cgfm2's SC-3000 // documentation, in the meanwhile, filling with 0xFF allow the game to work) According to SC3000 notes, the correct mapping for that game is the one below: $0000-$3FFF : ROM $4000-$7FFF : ROM (mirror) $8000-$BFFF : RAM (mirrored repeatedly every 2K) $C000-$FFFF : Work RAM (mirrored repeatedly every 2K) For some reason, the game is actually reading data from unmapped memory ($8000-$BFFF) which should normally read $FF since the RAM chip is not present. If you return value from a large ROM buffer that was either initialized with zeroes (like I did) or hold data from a previously loaded ROM (not 0xFF), the game will hang.

Maxim Site Admin Joined: 19 Oct 1999 Posts: 14741 Location: London	Posted: Mon Dec 11, 2017 1:08 pm
	The mirroring behaviour of games that don't fill the ROM address space is a bit tricky to manage as it's metadata missing from the ROM dumps.

dink Joined: 09 Dec 2013 Posts: 228 Location: detroit	Posted: Tue Dec 12, 2017 12:33 pm
dink Joined: 09 Dec 2013 Posts: 228 Location: detroit	Eke, thank you very much for this info!! I've been wondering this for a long time :D

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