几款MD原装日版卡带的区域兼容问题（US/JP)及NOMAD完美改法探讨

很早就将NOMAD加上了双制式切换（US/JP），简单的说就是将机器内部选择日版/美版（US/JP）的跳线接到START键上，这样START键不按(+5v)就是美版，按下（GND）就是日版。而MD系统对区域的检测一般都是在程序最开始（出现SEGA标志之前）只执行一次，检测一致则允许继续运行游戏，后面也不会再检测，而不一致则进入警告画面或直接停止运行程序。

这样，对于大部分有区域限制的日版卡带来说，只要按住START键不放再开机，就能正常进入游戏。不过最近遇到两块卡出现了异常：兽王记和超级大战略，这两块卡都是带区域限制的，美版机器状态下是无法进入游戏的，按住START不放再开机，出现了SEGA标志，然后进入了游戏，然而此时把START键放开，游戏马上中断停滞，再按住START键，重新出现SEGA标志，游戏重新开始。

也就是说，这两块卡所执行的区域检测是实时进行的，一刻也不停，在硬件上来说，也就是必须一直切换在JP跳线上才能正常游戏。这下麻烦大了，要不就一直按住START不松手，理论上这样是可以进入游戏的，不过START键被占用的话谈何从主菜单进入游戏呢？即使能进入游戏，NOMAD的START键设计是实时扫描的，也就是说按下去不放=START连发....

有人要说了，为啥用START来切换，用MODE键不是更好吗？嗯，好是好，不过NOMAD的无敌6B按键就被阉割成3键了.... >_<

最完美的改法应该是机器改为默认日版，通过某键来切换到美版，球达人提供改法，最好是简单的连线法而不要另装DIP开关...


再贴下NOMAD的经典免按键飞线全制式改法（个人感觉其中PAL/NTSC切换是多余，只改US/JP即可）：
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[size=+1]How to modify a Nomad without a Switch

[size=-1]Control your Nomad's country code by holding either A or Start button on bootup! A simple modification using only two wires.

[size=+2]Theory [size=-1]Based on the data from two other pages (Genesis 2 import mods and the Controller Primer) it dawned on me that it would be very easy to make a one-wire mod for the Nomad to switch country codes. To recap: The Genesis controller holds each button at +5v until pressed, at which point it drops to 0v. If you attach a wire from any button's NON-COMMON pin you can control the voltage to the region select pin. Coincidently this pin also operates at 0v or +5v. [size=+2]The Operation [size=-1]Open your nomad and locate the country code jumpers JP1, JP2, JP3 + JP4 (see here). Cut the jumpers currently hard-wired, shown below with scissor icons. Next, attach a wire to either of the center two jumper pads. Now close up this half of the Nomad, and look at the opposite side's PCB, shown below: Connect the wire from JP3 + JP4 to the Start button (pin 1) and the other to the A button (pin 23). Now your START button controls PAL/NTSC, and the A button is Japan/US mode. Note! Pressing start to pause a game will cause the nomad screen to shrink as it enters PAL mode (Or vice-versa). This will NOT harm your nomad. You CAN connect the PAL wire to another button, but if you use MODE you will enter PAL mode every time you turn off the six buttons, and having your screen shrink every time you press B really SUCKS. Trust me on this.

[ 本帖最后由 hkt3010 于 2010-10-15 12:26 编辑 ]