Posts: 151
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Joined: Oct 2009
The HP-65 used six bit op codes to store its programs; the HP-67 and 97 used 8 bit codes. No machine after the 65 could read its card data (programs or registers). Sorry.
Trivia - the 65's program storage was a dynamic shift register so the program was constantly circulated around same. There was no addressing for the data. The way a particular instruction was found was that a particular index value (all zeros if I recall) was stored *once* in the register. When that came by the read circuit, a counter was started. When the appropriate number of values clocked by after that, the desired value was read.
Of course, if more than one index value ended up in the program store the data read would be randomly chosen as so many values after either one. I'm still boggled that one of the old HP-65 Users Club members figured this all out on his own without any logic analyzers, oscilloscopes, internal documentation, etc.