Search found 6 matches

by raq
Fri Jan 09, 2015 7:45 pm
Forum: Mega/SegaCD
Topic: MegaCD2 Japan Bios on PAL MegaCD2
Replies: 23
Views: 8872

ooops, my mistake on too many zeroes :oops:

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.
by raq
Sat Jan 03, 2015 2:07 pm
Forum: Mega/SegaCD
Topic: MegaCD2 Japan Bios on PAL MegaCD2
Replies: 23
Views: 8872

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?
by raq
Thu Jul 04, 2013 5:54 pm
Forum: Tools
Topic: aPLib decruncher for 68000
Replies: 48
Views: 20455

I see it now :oops:, nice trick, eliminates the need for a counter as well
by raq
Thu Jul 04, 2013 5:23 pm
Forum: Tools
Topic: aPLib decruncher for 68000
Replies: 48
Views: 20455

Ahhhh okay, so what your saying is that bit 0 is always set to 1? How come? is this part of the compression design?
by raq
Thu Jul 04, 2013 11:38 am
Forum: Tools
Topic: aPLib decruncher for 68000
Replies: 48
Views: 20455

Syntax Error

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 ...
by raq
Thu Apr 15, 2010 7:07 pm
Forum: Mega/SegaCD
Topic: Mega-CD UniBios
Replies: 4
Views: 5435

Mega-CD UniBios

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...