I know this will be of minority interest but I feel it's worth noting anyway.
German Zeddy forum member Bokje has discovered a bug in the H4TH ROM which from a maths perspective is quite important.
The thread on the German forum can be found here...
http://forum.tlienhard.com/phpBB3/viewt ... f=2&t=2151
Amongst my inane ramblings which you should just ignore, Bokje has posted a corrected ROM which for those of us who burn our own EPROMS is a boon but more importantly it can/should be added to the ROM folder of Eighty One or any emulator that uses this ROM.