Building a Z-80 (64bit!!!)

< THe Z180 is already down to 3 cycle/instruction, and the z380 is < down to 2 cycle/instr. But since the maximum clock rate of the < 180 is more than 50% higher than the 280, it's the way to go. No news to me. I'm running a modifed SB180 (z180) and also working with z280/12.5Mhz. I've looked at z380. < > of using. I have z80/10mhz parts however and the 2901s would barely d < > that. < < And if you try, most 10 MHz can run at 12 to 14 MHz. I've taken the 10Mhz part to 12.5Mhz. < < > FYI: z80S180s can be had into the 30+ mhz range. < :) Jep and 1 Meg is still plenty of RAM when running CP/M That it is. < But after all where is the sense of having a Z80 as 64 Bit < processor ? It's a well usable 8/16 Bit processor. Even the < 380 isnt really an advantage - you just don't realy need this < 32 Bit instructions. A set consecutive 16 Bit instructions Larger flat address space. The z380 would make a real good data handler (z382 is a PC bus slave version for comms) or possibly a graphics crunchers. Even in the z80 native mode you can access beyond the 64k basic addressing in a manor that is more convenient than the basic z80 provides. In most cases the extended mode changes the the effect of the arithmetic overflow in 16bit ops so that 0FFFFh+1 is not 0000. but 10000h. There are of course extended operations as addressing modes as well. < can do it in almost the same time. From my point of usage < a 16 Bit uP is anything you need - compact code, compact data < and greater over all performance. Z380 still has those attributes. It saves the memory management overhead for apps that need to get at spaces larger than 64k. I plan to do a bit of serious work with one if I can get my hands on a few and a socket adaptor. Allison