The CPU isn't halted - it's denied access to the bus. A lot of the time, this doesn't matter, which is presumably why they chose to do it that way, because most

The CPU isn't halted - it's denied access to the bus. A lot of the time, this doesn't matter, which is presumably why they chose to do it that way, because most 68000 instructions won't be accessing the bus at the time anyway. (Supposedly, if you have a long instruction that doesn't use the bus, such as DIVx or MULx, and you get your timing right, you can overlap it with the blitter, which on the ST always runs in some approximation of nasty mode - better you than me though.) More info (than you probably ever cared to know) here: http://pasti.fxatari.com/68kdocs/AtariSTCycleCounting.html http://pasti.fxatari.com/68kdocs/AtariSTCycleCounting.html