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Published 20 hours ago • verified publisher icon ocornut

Add mapper `#42` MAPPER_GG_Gear_6_in_1_FFFE_FFF7_FFFF for "Gear 6 in 1 [Alien Syndrome] (Unl)"

Open bsittler opened this issue 1 year ago • 0 comments

I've been calling it "Gear 6 in 1 [Alien Syndrome] (Unl)" but the actual name is not entirely clear

Name candidates:

GEAR 6 IN 1 [box, label] Box Front - Gear 6 in 1 (Unl)Box Top - Gear 6 in 1 (Unl) Box Left Side - Gear 6 in 1 (Unl) Box Right Side - Gear 6 in 1 (Unl) Box Bottom - Gear 6 in 1 (Unl)

PCB Back - Gear 6 in 1 (Unl)PCB Front and Cartridge Front - Gear 6 in 1 (Unl) 6 IN 1 [menu screen] 六合一卡 (i.e. "6-in-1 card") [bumper screen] Menu - Gear 6 in 1 Alien Syndrome (Unl)-01

Other text on both the label and the box:

畫面選遊戲 (i.e."game selection on screen") SCREEN SELECT

The box also has a game list in both English and Traditional Chinese: Box Back - Gear 6 in 1 (Unl)

ALIEN SYNOROME 異形風暴 (i.e. "Alien Storm")
OUT RUN 瘋狂大賽車 (i.e. "crazy grand prix"/"wacky races", a name apparently associated with Out Run in Taiwan)
AERIAL ASSAULT 藍天特攻隊 (i.e. "blue sky commando")
COLUMNS 寶石方塊 (i.e. "gem cube", a name by which Columns is sometimes known in Chinese)
PENGO 企鵝推冰 (i.e. "penguin pushes ice" or "Pengo")
WOODY POP 玩具磚王 (i.e. "toy brick king")

This is a 512KB multicart containing a 32KB menu, three 32KB Game Gear games (Columns, Pengo, and Woody Pop) and three 128KB Game Gear games (Alien Syndrome, Out Run, and Aerial Assault.) All games are modified to remove or obscure original manufacturer/copyright information.

Initially the first 16KB of the menu is mapped into 0x0000..0x3FFF, 0x4000..0x7FFF, and 0x8000..0xBFFF

On startup the menu code writes to 0xFFFE to map the second 16KB of the menu code into 0x4000..0x7FFF

There is a bumper screen that appears briefly and then vanishes before the menu appears

Activating a menu item writes a mapper sequence to 0xFFFE, 0xFFF7, 0xFFFE

The menu code appears to be based on Pengo, but has been modified such that it is no longer playable as Pengo. Instead, there is a separate playable copy of Pengo elsewhere in the multicart.

NOTE: The menu uses a movable reversed angle cursor "⦣" to mark the current selection. Its initial position is shown in the screen below.

Menu screen: Menu - Gear 6 in 1 Alien Syndrome (Unl)-02


      6 IN 1

⦣1 ALIEN SYNDROME  [0xFFFE=0x08, 0xFFF7=0x04, 0xFFFE=0x01]

 2 OUT RUN         [0xFFFE=0x00, 0xFFF7=0x05, 0xFFFE=0x01]

 3 AERIAL ASSAULT  [0xFFFE=0x08, 0xFFF7=0x05, 0xFFFE=0x01]

 4 COLUMNS         [0xFFFE=0x02, 0xFFF7=0x04, 0xFFFE=0x01]

 5 PENGO           [0xFFFE=0x04, 0xFFF7=0x04, 0xFFFE=0x01]

 6 WOODY POP       [0xFFFE=0x06, 0xFFF7=0x04, 0xFFFE=0x01]


 PUSH ↑↓AND START

Apparent mapper register meanings in the initial menu mode:

0xFFF7: writing to this register activates a new mapping and leaves menu mode

  • bit 0x04 is always set in mapper writes. maybe it indicates native-GG mode?
  • bit 0x01 is set to activate the second 256KB of the ROM, otherwise the first 256KB will be activated
  • the low 4 bits from 0xFFFE select the 16KB starting page for the mapping

0xFFFE: paging and base page control

  • bit 0x01 sets the 16KB page number for 0x4000..0x7FFF
  • bits 0x0F select the 16KB starting page within the selected 256KB ROM region to be activated by a subsequent write to 0xFFF7

0xFFFF: paging

  • bit 0x01 sets the 16KB page number for 0x8000..0xBFFF

Once a mapping is chosen, 0xFFFE and 0xFFFF work Sega-style for mapping up to 128KB from the selected starting page.

0xFFFE: paging

  • bits 0x07 select the 16KB page number for 0x4000..0x7FFF

0xFFFF: paging

  • bits 0x07 select the 16KB page number for 0x8000..0xBFFF

No mechanism for returning to the initial "menu" mapping is known other than resetting.

The ROM was fully dumped using only four different base page mappings, by using the 128KB Sega mapper capability with the base page set to each multiple of 128KB.

ROM fingerprint info:

512K Gear 6 in 1 [Alien Syndrome] (Unl).gg Checking for export header with matching CRC... NO sha256:5b5f9d920003df9e7dafb9e6466cf75ba28278d5de29fde0f624b378be3efc8e Gear 6 in 1 [Alien Syndrome] (Unl).gg sha1:9f128b4c9b36178b2510a8a4f9e3f2b95556d1da Gear 6 in 1 [Alien Syndrome] (Unl).gg md5:ceb4569927bf8041a024bde5238fec59 Gear 6 in 1 [Alien Syndrome] (Unl).gg mekacrc:380E4248BE33AC93 Gear 6 in 1 [Alien Syndrome] (Unl).gg crc32:983ffa6c Gear 6 in 1 [Alien Syndrome] (Unl).gg

32K Gear 6 in 1 [Alien Syndrome] (Unl)/part-00-menu-32k.gg Checking for export header with matching CRC... NO sha256:da119ac191f63c83b8af257add9ac175382cafbab449fbce5322fb69a3e85980 Gear 6 in 1 [Alien Syndrome] (Unl)/part-00-menu-32k.gg sha1:a0b3198a9a1e55d84e7a8c0480fa240d708cd552 Gear 6 in 1 [Alien Syndrome] (Unl)/part-00-menu-32k.gg md5:2c558e9528717d41cb2851fcb3df00f0 Gear 6 in 1 [Alien Syndrome] (Unl)/part-00-menu-32k.gg mekacrc:D702012148168B1C Gear 6 in 1 [Alien Syndrome] (Unl)/part-00-menu-32k.gg crc32:4f7c5865 Gear 6 in 1 [Alien Syndrome] (Unl)/part-00-menu-32k.gg

32K Gear 6 in 1 [Alien Syndrome] (Unl)/part-02-columns-32k.gg Checking for export header with matching CRC... NO sha256:73f6012c1a92bcc96497668cdecfb3b592162c6b39a8c7efb8b9dc3931380561 Gear 6 in 1 [Alien Syndrome] (Unl)/part-02-columns-32k.gg sha1:26d407e8389a5564b836f0a68585a935ca019802 Gear 6 in 1 [Alien Syndrome] (Unl)/part-02-columns-32k.gg md5:bfcf0e46ec8df8a51776bd2315b859fc Gear 6 in 1 [Alien Syndrome] (Unl)/part-02-columns-32k.gg mekacrc:1DE54704572F032A Gear 6 in 1 [Alien Syndrome] (Unl)/part-02-columns-32k.gg crc32:7316423e Gear 6 in 1 [Alien Syndrome] (Unl)/part-02-columns-32k.gg

32K Gear 6 in 1 [Alien Syndrome] (Unl)/part-04-pengo-32k.gg Checking for export header with matching CRC... NO sha256:1c221bcb0b7ef67e644a695b78cb4dd851b800202ee13fd8d03fb099e533c46a Gear 6 in 1 [Alien Syndrome] (Unl)/part-04-pengo-32k.gg sha1:126654feb2975e3a52431d29cefcafbd37bb2ef5 Gear 6 in 1 [Alien Syndrome] (Unl)/part-04-pengo-32k.gg md5:69bf00297cad6ee0bb6046c8084e5e37 Gear 6 in 1 [Alien Syndrome] (Unl)/part-04-pengo-32k.gg mekacrc:6C3C703170EBD587 Gear 6 in 1 [Alien Syndrome] (Unl)/part-04-pengo-32k.gg crc32:6bd56e95 Gear 6 in 1 [Alien Syndrome] (Unl)/part-04-pengo-32k.gg

32K Gear 6 in 1 [Alien Syndrome] (Unl)/part-06-woody-pop-32k.gg Checking for export header with matching CRC... NO sha256:0c23fccffa3160b6754fa54ecbf08d3828f5e60a64dbe4203109715644ad94ce Gear 6 in 1 [Alien Syndrome] (Unl)/part-06-woody-pop-32k.gg sha1:58516c23f1e1b87daebda1b971fab278a6e7ce59 Gear 6 in 1 [Alien Syndrome] (Unl)/part-06-woody-pop-32k.gg md5:3885c64be1dc990918adebcbe9675855 Gear 6 in 1 [Alien Syndrome] (Unl)/part-06-woody-pop-32k.gg mekacrc:9D2A47DDDF12FD27 Gear 6 in 1 [Alien Syndrome] (Unl)/part-06-woody-pop-32k.gg crc32:0c6e4769 Gear 6 in 1 [Alien Syndrome] (Unl)/part-06-woody-pop-32k.gg

128K Gear 6 in 1 [Alien Syndrome] (Unl)/part-08-alien-syndrome-128k.gg Checking for export header with matching CRC... NO sha256:cf2d5699fa3be4784395555b64049f09dd2cbadfda15d0d7078d50ea76940541 Gear 6 in 1 [Alien Syndrome] (Unl)/part-08-alien-syndrome-128k.gg sha1:9efd760ab7b49d26cf1670785e6f0475b34a45cf Gear 6 in 1 [Alien Syndrome] (Unl)/part-08-alien-syndrome-128k.gg md5:f580d5933ea6038d203bf8624f2c0614 Gear 6 in 1 [Alien Syndrome] (Unl)/part-08-alien-syndrome-128k.gg mekacrc:1E4A241E09A3EBBF Gear 6 in 1 [Alien Syndrome] (Unl)/part-08-alien-syndrome-128k.gg crc32:0cbcf85a Gear 6 in 1 [Alien Syndrome] (Unl)/part-08-alien-syndrome-128k.gg

128K Gear 6 in 1 [Alien Syndrome] (Unl)/part-10-out-run-128k.gg Checking for export header with matching CRC... NO sha256:3d217996a52b84d37bac44b74156839c3e6e885d579393c539f1399ee28692b6 Gear 6 in 1 [Alien Syndrome] (Unl)/part-10-out-run-128k.gg sha1:882e2a321550cefde0394ea22ac43b1d641fbbd4 Gear 6 in 1 [Alien Syndrome] (Unl)/part-10-out-run-128k.gg md5:dbee3842952484b7477b92bdf9396a1b Gear 6 in 1 [Alien Syndrome] (Unl)/part-10-out-run-128k.gg mekacrc:34AB681335239EB0 Gear 6 in 1 [Alien Syndrome] (Unl)/part-10-out-run-128k.gg crc32:e918e2d8 Gear 6 in 1 [Alien Syndrome] (Unl)/part-10-out-run-128k.gg

128K Gear 6 in 1 [Alien Syndrome] (Unl)/part-18-aerial-assault-128k.gg Checking for export header with matching CRC... NO sha256:67c7d473ad3e94c30c2e09dbf7b624d3d5a36bb77c53942d91ebeb7856e95fdc Gear 6 in 1 [Alien Syndrome] (Unl)/part-18-aerial-assault-128k.gg sha1:e474bdd375120aa866028d2ff3b1e757277a8edd Gear 6 in 1 [Alien Syndrome] (Unl)/part-18-aerial-assault-128k.gg md5:1ef1c76eff247c6d61336d8232d13863 Gear 6 in 1 [Alien Syndrome] (Unl)/part-18-aerial-assault-128k.gg mekacrc:E9CCB7E4922BC330 Gear 6 in 1 [Alien Syndrome] (Unl)/part-18-aerial-assault-128k.gg crc32:076185b9 Gear 6 in 1 [Alien Syndrome] (Unl)/part-18-aerial-assault-128k.gg

bsittler avatar Apr 10 '23 21:04 bsittler