On Thu, 21 Aug 2008 02:30:27 GMT, [EMAIL PROTECTED] wrote: >On Wed, 20 Aug 2008 21:18:22 -0500, [EMAIL PROTECTED] (Rob Warnock) wrote: > >>Martin Gregorie <[EMAIL PROTECTED]> wrote: >>+--------------- >>| I was fascinated, though by the designs of early assemblers: I first >>| learnt Elliott assembler, which required the op codes to be typed on >>| octal but used symbolic labels and variable names. Meanwhile a colleague >>| had started on a KDF6 which was the opposite - op codes were mnemonics >>| but all addresses were absolute and entered in octal. I always wondered >>| about the rationale of the KDF6 assembler writers in tackling only the >>| easy part of the job. >>+--------------- >> >>In the LGP-30, they used hex addresses, sort of[1], but the opcodes >>(all 16 of them) had single-letter mnemonics chosen so that the >>low 4 bits of the character codes *were* the correct nibble for >>the opcode! ;-} >> >>[Or you could type in the actual hex digits, since the low 4 bits >>of *their* character codes were also their corresponding binary >>nibble values... "but that would have been wrong".] >> >> >>-Rob >> >>[1] The LGP-30 character code was defined before the industry had >> yet standardized on a common "hex" character set, so instead of >> "0123456789abcdef" they used "0123456789fgjkqw". [The "fgjkqw" >> were some random characters on the Flexowriter keyboard whose low >> 4 bits just happened to be what we now call 0xa-0xf]. Even worse, >> the sector addresses of instructions were *not* right-justified >> in the machine word (off by one bit), plus because of the shift- >> register nature of the accumulator you lost the low bit of each >> machine word when you typed in instructions (or read them from >> tape), so the address values you used in coding went up by *4*! >> That is, machine locations were counted [*and* coded, in both >> absolute machine code & assembler] as "0", "4", "8", "j", "10", >> "14", "18", "1j" (pronounced "J-teen"!!), etc. >> >>----- >>Rob Warnock <[EMAIL PROTECTED]> >>627 26th Avenue <URL:http://rpw3.org/> >>San Mateo, CA 94403 (650)572-2607 > > >Whats os interresting about all this hullabaloo is that nobody has >coded machine code here, and know's squat about it. > >I'm not talking assembly language. Don't you know that there are routines >that program machine code? Yes, burned in, bitwise encodings that enable >machine instructions? Nothing below that. > >There is nobody here, who ever visited/replied with any thought relavence that >can >be brought foward to any degree, meaning anything, nobody.... > >sln
At most, your trying to validate you understanding. But you don't pose questions, you pose terse inflamatory declarations. You make me sick! sln -- http://mail.python.org/mailman/listinfo/python-list
