8080 Assembler-Text Editor (ATE)

I'm not promoting the Octal side (indeed I much prefer HEX), however Zilog didn't "opt" for anything - they based their design and instruction set decoding on the Intel 8080, which was laid out in a manner which made sense with "Octal". And Intel DIDN'T use xsddsdsx, they DID use xxdddsss - which made perfect sense from an Octal standpoint (which is why so many people promoted the use of Octal with it). By the time the Z80 was common, so were good assemblers and debuggers - but when the 8080 (ie: this instruction set) was designed, there was no such software commonly available for "personal use" - chances are your assembler was a pad of paper, a pencil and the Intel databook (thats how I wrote my earliest software). More often than not the debugger was a set of binary switches, or if you were really high- tech, a very simple poke into memory monitor squeezed into a 1702. The only "symbolic" thing about it was the pad of paper (sometimes it was an integrated symbolic assembler/debugger, where you wrote out the code on one side of the pad, the hex opcodes in the middle and patches/debug notes on the right - of the same pad). Thats why a lot of people opted for Octal with the 8080 - in Octal the instruction set was fairly easy to remember ... For example '1sd' gave you all the MOV combinations. If you had the instruction set and it's encoding committed to memory, you could go a LOT faster during the "assembly phase". It also made debugging easier. I never got to like Octal, so I worked in hex anyway - I made "cheat sheets" to look up the opcodes, which I eventually memorized - I could go faster than most of the "Octal" guys... Agreed - one of the things I disliked most about Octal was the ambiguity over representation of 16-bit quantities, and the fact that you had to either "convert" to do it "right", or put up with a little 2/3 digit in the middle (which made mental arithmetic challenging) - The fact that you could just "stick two hex bytes together" was reason enough for me to keep with it. BTW - something I forgot to mention in my earlier post, Mits wasn't going against "Everyone else" - there were a number of other companies which embraced Octal for the 8080. Heath is another "biggie", but I saw a good chunk of other Octal based equipment during the time period. Regards, Dave -- dave06a (at) Dave Dunfield dunfield (dot) Firmware development services & tools: www.dunfield.com com Collector of vintage computing equipment: http://www.parse.com/~ddunfield/museum/index.html