The Importance of Terminology's Quality

sln at sln at
Thu Aug 21 04:30:27 CEST 2008

On Wed, 20 Aug 2008 21:18:22 -0500, rpw3 at (Rob Warnock) wrote:

>Martin Gregorie  <martin at see.sig.for.address.invalid> 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".]
>[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			<rpw3 at>
>627 26th Avenue			<URL:>
>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....


More information about the Python-list mailing list