[Simh] Announcement: back10

[Lars Brinkhoff]

Johnny Billquist wrote:
>> So one 36-bit word AAAAAAABBBBBBBCCCCCCCDDDDDDDEEEEEEEF becomes the five
>> octets 0AAAAAAA 0BBBBBBB CCCCCCC 0DDDDDDD FEEEEEEE.
>
> I think you forgot one 0 before the Cs. :-)

Oh, yes.

> But ok, such an encoding would work. But then your PDP-10 7-bit ASCII
> files might not truly convert into 8-bit ASCII files... That final bit
> can be a zero or a one... Some code on a PDP-10 did use that last bit
> as well, when playing with 7-bit text, if I remember right.

That's right.  I understand some programs encoded a line number in a
word with the final bit set.  But I would not call those pure text
files.

I never heard of any other kind of text files with the final bit set.
But there could be.

> But I don't know how important you think the property of retaining
> text file "compatibility" is.

If you were to display those converted files with line numbers, I guess
you would see five strange characters at the beginning of every text
line.

I propse that handling this would be done outside of a 36-bit <-> octet
transformation.  Same as line ending conversion between CRLF and
newline.