ASCIZ
Lost in the mists of time in my mind.

I remember running into a .asciz directive n the 70s “somewhere”.
It was an assembler directive in one of the RT11 systems??? or perhaps the unix bootstrap and/or “.s” files - when I get some time I will go read some old code/manuals.

I

Yes, it put a null byte at the end of a string.

> On 16 Dec 2022, at 03:14, Ken Thompson <kenbob@gmail.com> wrote:
> 
> asciz -- this is the first time i heard of it.
> doug -- yes.
> 
> 
> On Thu, Dec 15, 2022 at 7:04 PM Douglas McIlroy <douglas.mcilroy@dartmouth.edu <mailto:douglas.mcilroy@dartmouth.edu>> wrote:
> I think this cited quote from
> https://www.joelonsoftware.com/2001/12/11/ <https://www.joelonsoftware.com/2001/12/11/> is urban legend.
> 
>     Why do C strings [have a terminating NUl]? It’s because the PDP-7
> microprocessor, on which UNIX and the C programming language were
> invented, had an ASCIZ string type. ASCIZ meant “ASCII with a Z (zero)
> at the end.”
> 
> This assertion seems unlikely since neither C nor the library string
> functions existed on the PDP-7. In fact the "terminating character" of
> a string in the PDP-7 language B was the pair '*e'. A string was a
> sequence of words, packed two characters per word. For odd-length
> strings half of the final one-character word was effectively
> NUL-padded as described below.
> 
> One might trace null termination to the original (1965) proposal for
> ASCII,  https://dl.acm.org/doi/10.1145/363831.363839 <https://dl.acm.org/doi/10.1145/363831.363839>. There the only
> role specifically suggested for NUL is to "serve to accomplish time
> fill or media fill." With character-addressable hardware (not the
> PDP-7), it is only a small step from using NUL as terminal padding to
> the convention of null termination in all cases.
> 
> Ken would probably know for sure whether there's any  truth in the
> attribution to ASCIZ.
> 
> Doug