< seems though, everybody wrote assembler code so that either the s/w chec < to see which processor was used or wrote straight 8080 asm code to just < cover everybody without having the extra CPU checking code taking up spa < Most commercial language interpreters and compilers, especially from Hea < handled 8080-based machines for sure. Generally true but, not absolutley so.. however some bios used Z80 code to do disk io or used 8080 code tricks that do not run on z80. Come from having aboth an 8085 powered s100 (explorer 8085) and a slew of z80 systems. < Allison, for the H8 there were at least two third-party Z80 CPU boards m < (I can look up the mfgrs if anybody wants) and a Heath-made Z80 board. I'm well aware of them and helped several friends bring them up. < Early on when the Z80 became rather popular, the original 8080 CPU boar < was of course found to be lacking in performance compared to the TRS-80' < N*, Kaypros, various S100's and other contemporary CP/M Z80 machines. < Hence, the little cottage industry, so to speak, which sprang up to dea < with making Z80 boards. A 4 MHz CPU by DG Micro (I think that's the name I went to z80 in early 1977 as the 8080 already had a case of impending doom being limited to 2mhz and fewer instructions. The better instruction set of the z80 was enough in itself. < really was a performer up against many other machines. The H-89 was a Z8 < machine when it first was introduced around 1980 or thereabouts. Yes, h89 was mid 1980, by then the z80 had permutated the software for cpm systems. Consider that S100 system ahd all pretty much gone z80 by 1978 and the few non z80 systems were either dual processsor like Compupro 8/16 or oddball the Autocontrol AC85 (8085/5mhz). The ZCPR CCP replacement and widespread use of z80s made for major software like languages to be 8080 compatable at the expense of performance while the system would have a bios written using z80 extended. Allison