This is a complete HP 9100 Calculator system. It includes a HP 9100B calculator with the HP 9120A printer mounted on top. The complete set of manuals is to the left of the calculator. The HP 9101A Extended Memory unit is shown to the right and the HP 9125B Plotter is shown on top of it. To the left in front of the extended memory is a single magnetic card used for recording calculator programs and data. To the right of it are two plastic flip top box used for storing the cards. Not shown in this image is the HP 9102A Buffer.
The HP 9101 Extended Memory adds XXX additional registers to the calculator system. On the top you an see the connector that plugs into the calculator or the buffer. Here is an orthogonal view showing the two front handles and one of the two side handles. The fact that it has four handles should give you an idea of the weight! Here is a picture of the back of it. In this clasp of the serial number tag you may notice something strange. According to it, this unit was made in the 80th week of 1969!
Here is a picture of the back of the calculator and printer. You can see the port where the printer is connected to the calculator. If more than one peripheral is to be connected, then the HP 9102 buffer must be used to connect all of them.
This is what the system looks like when covered. Here is the calculator and printer and here is the Plotter.