Semi-OT: IDE & SATA to USB "dongles"

[Tony Duell]

> Early 7400-series TTL had the 7450 and 7453 AND-OR-INVERT gates that could
> be explanded with another 4 inputs via the 7460 dual 4-input expander.  I'd
> hate to own equipment now that used some of those that required
> replacement--they must be very difficult to find.

There were at least 2 different expanders, I forget the number of the 
other one.

The HP98x0 machines use these gates as the input selectors to the 
bit-serial ALU (and I think to the T register (memory data register)). I 
did have a 74H52 fail in one 9810 (that's an AND-OR gate), fortunately, 
not much of it is used in _that machine_ and I could dead-bug in a 
74LS51. That wouldn't work in the 9830, or I assume the 9820 (not looked 
at the hardware of that machine yet, next project) as those use rather 
more input sections of the AND-OR gate.


-tony