Which paper tape hole is bit 1?
vrs
vrs at msn.com
Sat Nov 19 11:06:33 CST 2005
From: "Allison":
> Nominal PDP-8 use was short BIN loader hand toggled in. Load bin
> tape that contains small BIN format program or loads the RIM
> loader for more complex programs (basic, focal). BASIC would
> then read an ascii program tape.
It's a nit, but you have the roles of BIN and RIM reversed in
this paragraph. You also omitted a discussion of the checksum,
field setting, and comment features allowed in a BIN tape :-).
For those who care, BIN tapes have an extra 'data' pair at the
end which forms a checksum. Bytes with both of the most significant
bits set use the next three bits to select which bank or 'field'
is loaded. And arbitrary 'comments' may appear between rub-outs
(which have all bits set). RIM tapes have none of these features.
Both BIN and RIM tapes use leader-trailer with just the MSB set.
There are at least two versions of the BIN loader. I don't know
offhand if the older BIN loader supported all the features or
not.
Vince
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