The model 1155 is a calculator having a program capacity of 511 instruction steps, two working registers, and twenty data storage registers (each independent of program storage and working registers). Register capacity is 13-digits with a 2-digit exponent, plus decimal point and sign. Its dynamic range is: 10-99 to 1099. A plug-in magnetic card reader/recorder, reads and/or writes two 511 step programs. Provision is also made for plugging in an X-Y plotter. The printed tape output is accomplished by a small compact single print wheel, helical printer under control of the 1155 logic.