ooops, my mistake on too many zeroes
There is a bit in the config register of the everdrive thats set when a BIOS is flashed to the everdrive, so maybe the fpga traps addresses 0x20000 - 0x3ffff and 0x200000 - 0x23ffff and sets CART_IN high when in this range.
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- Sat Jan 03, 2015 2:07 pm
- Forum: Mega/SegaCD
- Topic: MegaCD2 Japan Bios on PAL MegaCD2
- Replies: 23
- Views: 12579
Isn't it the case when a cart is inserted the CD BIOS (the original one in the Mega-CD) gets mapped to 0x40000000 and cart is mapped to 0x00000000 and this swaps around when cart is removed?
Think there may be a mistake in your optimization ; get_bit: Get bits from the crunched data (D3) and insert the most significant bit in the carry flag. get_bit: add.b d3,d3 ; move MSB to C and X bne.b still_bits_left ; error!!! what if we have an end sequence of 0 bits? move.b (a0)+,d3 ; Read next ...
Here is a 'hack' of the european Mega-CD BIOS v1.00 that bypasses the country code and CD protection. This is a very basic hack and there are a few 'glitches' with it. The two I know of (and can't do nothing about) are that if you use this BIOS on 60Hz machines (USA Genesis, JAP Mega Drive) there is...