On: raising the semantic level of a program

Rich Alderson RichA at livingcomputers.org
Mon Jun 29 14:41:53 CDT 2020

From: Chuck Guzis 
Sent: Sunday, June 28, 2020 4:51 PM

> It's noteworthy that on the Univac 1100 series, a "byte" could be 6, 9
> or 12 bits, but not 8. (36 bit words).  The PDP-10 had similar issues,
> such as the "packed" string format of 5 7-bit characters per word, with
> one bit unused.

Of course, on the PDP-10, bytes can be anywhere from 1 to 36 bits long;
the size is defined in the pointer, not the hardware.

And in the 7-bit ASCII text format, bit 35 (the word is big-endian) *is*
used by the default editor:  In order to allow line numbering in source
files for languages which do not allow it, the line numbers are ASCII
strings with bit 35 set, and the monitor (=kernel=operating system) strips
them out before handing them to compilers' input streams.


Rich Alderson
ex-Sr. Systems Engineer/Curator emeritus
Living Computers: Museum + Labs
2245 1st Ave S
Seattle, WA 98134

Cell: (206) 465-2916
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NB: This e-mail address will cease working after 1 July 2020. Use lcml at alderson.users.panix.com for future communications.

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