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SEGA CD Mode 1 Player

Discussion in 'Technical Discussion' started by Chilly Willy, Dec 17, 2011.

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  1. Dec 20, 2011 #21
    Sik

    Sik

    Sik is pronounced as "seek", not as "sick". Tech Member
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    being an asshole =P
    Probably because there isn't really a different way to approach it...

    EDIT: I was right to be suspicious about this method, it does not work with all BIOSes:

    Code (Text):
    1. [BIOS] CDX (USA) (v2.21X) ...................... $016000
    2. [BIOS] LaserActive (Japan) (v1.02) ............. $00D500/$01AD00?
    3. [BIOS] LaserActive (USA) (v1.02) ............... $00D500/$01AD00?
    4. [BIOS] LaserActive (USA) (v1.04) ............... $00D500/$01AD00?
    5. [BIOS] Mega-CD 2 (Europe) (v2.00) .............. $016000
    6. [BIOS] Mega-CD 2 (Europe) (v2.00W) ............. $016000
    7. [BIOS] Mega-CD 2 (Japan) (v2.00C) .............. $016000
    8. [BIOS] Mega-CD (Asia) (v1.00S) ................. $016000
    9. [BIOS] Mega-CD (Europe) (v1.00) ................ $015800
    10. [BIOS] Mega-CD (Japan) (1.00l) ................. $016000
    11. [BIOS] Mega-CD (Japan) (1.00S) ................. $016000
    12. [BIOS] Mega-CD (Japan) (v1.00P) ................ $016000
    13. [BIOS] Multi-Mega (Europe) (v2.21X) [b] ........ $016000
    14. [BIOS] Sega CD 2 (USA) (v2.00) ................. $016000
    15. [BIOS] Sega CD 2 (USA) (v2.00W) ................ $016000
    16. [BIOS] Sega CD 2 (USA) (v2.11X) ................ $016000
    17. [BIOS] Sega CD (USA) (v1.00) ................... $015800
    18. [BIOS] Sega CD (USA) (v1.10) ................... $015800
    19. [BIOS] WonderMega (Japan) (v1.00) (Sega) ....... $016000*
    20. [BIOS] WonderMega M2 (Japan) (v2.00) ........... $016000*
    21. [BIOS] X'Eye (USA) (v2.00) ..................... $016000*
    LaserActive has the BIOS code at a different address. Also for the WonderMega-based ROMs (the ones marked with an asterisk) the string "SEGA" isn't present at $016000, but rather "WONDER".

    (of course, add $400000 to all those addresses when running code off a mode 1 program)

    EDIT: addenum, found another possible location for the BIOS in the LaserActive: $01AD00 x_x
     
  2. Dec 20, 2011 #22
    Chilly Willy

    Chilly Willy

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    Good job there, Sik. That's just the info needed to make the startup work on everything. It's part of the reason I posted this with code - people could see what was going on and contribute where they could... like in finding the different BIOS locations on "odd" consoles like the Laser Active.
    :)

    EDIT: Looked at the roms myself - simply checking for "WONDER" as well as "SEGA" at 0x16000 (+0x6D) will take care of the WonderMega/XEye. As for the LaserActive, I suspect one of those is the Sub-CPU BIOS for for LD games, and the other for regular CDs. Someone with an LA will have to try it to see which handles CDs.

    EDIT 2: Okay, here's a quick update. It should work on the WonderMega and X'Eye, and might work on the LaserActive. It also inits the drive if there is a disc in on startup. See how easy it is to make these changes? :)

    http://www.mediafire.com/?88m8r5iaij52sdk
     
  3. Jan 5, 2012 #23
    Chilly Willy

    Chilly Willy

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    Updated OP with latest version. Now works with the LaserActive, finishing the list of supported models. :)
     
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