Another nice calculator find for the collection is my CS-2115. It is a 12 digit calculator with a vacuum fluorescent display, memory, and several extra functions.

The Sharp CS-2115 was introduced in 1979 and had another variation outside of the US and Canada, which included a 000 entry key. The calculator is a single chip design with a few supporting components mainly for the power supply. The CS-1115 is a 10 digit version of this calculator with the only difference being two less digits.

The unit is AC line powered with 120 VAC at 60 Hz with a 2.3 Watt power consumption. The power transformer only has a single primary winding, so no other voltage options are available internally. The single secondary output of the transformer is 7.2 VAC.

The case bottom has two battery compartment doors, which are unused on this model. The same case is used for several other Sharp calculator models.

The top case is easily removable with 5 screws and a plastic snap on each side. There are no components attached to the case top which includes a green filter bezel for the display which is attached by three melted plastic posts.

The unit was fully functional when I received it, but I wanted to change out the 40+ year old electrolytic capacitors as part of the general maintenance, Overall the unit was in great shape with a scratch free display bezel, and only required general cleaning.

The main board is a very simple single sided phenolic circuit board with a single 36 pin IC. The calculator on a chip IC is a SC38402 used in many different Sharp calculator models.
There are five electrolytic capacitors with four smaller capacitors close to the transformer, and a larger unit soldered behind the VFD display. The larger round component seems to be a 10 pin TO-100 package TDK switching voltage regulator. A quick check showed a switching frequency of 144 KHz, and several voltages including 26 volts for the VFD.

The keypad, switches and Futaba 13MT54S VFD display are also attached directly to the main circuit board.



Overall the CS-2115 is a great calculator with a sharp easy to read green tinted display, the keys are laid out nicely with a good spacing and a positive keypress feeling with a quiet but noticeable sound produced at the ends of key travel.
Personally I like the overall style and look of this calculator. The putty colored plastic has a non-shiny matte finish, which is accented by the metal band placed across the upper row of switches. This calculator currently resides on my main computer desk and is used daily.

The extra functions on this calculator include: Item Count, Right shift, Square root, Register swap, Percent, Change sign, Multiple Use markup, Accumulation selector, Constant select, Rounding selector, Decimal/Add mode selector, and memory functions.
