I got the awesome Viper 520CD which gives 8Mb Fast RAM, 68020/68882FPU, 3.0 ROMs and IDE interface for adding a 2.5" IDE harddrive internally. Unfortunately they seem to be very hard to find. (got mine brand new in Australia!...the last one!)
I wish I could add even more memory though. Has anybody out there successfully modified a Viper 520CD to add more memory? (or does anyone have the elusive 530CD with 128Mb RAM??)
