> The reason there are two DECtape controllers in the current PDP-8 > simulator is that one is block-by-block (TC) and the other is line-by-line > (TD), where "line" is 3 bits! That means there is a device driver in > TD-aware PDP-8 software that has to assemble incoming data 3 bits at a time! > > The TD8E is dumb but not THAT dumb. It do reassemble 12 bit words for the processor to deal with.
http://svn.so-much-stuff.com/svn/trunk/Eagle/projects/DEC/ Mxxx/M868/M868Hsch.pdf There are three four bit 8271 shift registers that handles it. Both for reading and writing.
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