27 May
2014
27 May
'14
3:14 p.m.
On 05/27/2014 12:10 PM, Rich Alderson wrote:
If it was a binary tape, it was 36 bit words, period.
ASCII text is stored as
5 x 7-bit bytes per word.
Or did you mean "5 *8-bit frames* per 36 bit word", for a total of 40 bits?
That was the general standard, called "core-dump format" on PDP-10 operating
systems. Even ASCII text, represented as stated above, ended up in core-dump
format on tape.
No, nothing at all to do with tape format, unless you count 2 36-bit
words mapping into 9 tape frames. This is the format in which a DEC CE
friend delivered "Adventure" to me. Converting to 6 bit CDC display
code was interesting, particularly since I didn't have any idea of how
the DECSystem 10 stored things. I am relatively certain that the CDC
conversion utility didn't have the vocabulary to unravel it.
Fortunately, it turned out that all I had to do was read two 36 bit
words' worth and translate them into a single 60 bit word, making
provision of the peculiar CDC end-of-line convention.
The game itself posed a few conversion challenges, but it turned into
one of the bigger resource hogs at the time.
--Chuck