![Karsten Suhre on Twitter: "@mims Does a programmable calculator count? Then it was a TI-58. But the oldest one I used was actually a Telefunken TR440 mainframe, running FORTRAN IV abd SPSS Karsten Suhre on Twitter: "@mims Does a programmable calculator count? Then it was a TI-58. But the oldest one I used was actually a Telefunken TR440 mainframe, running FORTRAN IV abd SPSS](https://pbs.twimg.com/media/D34pemAXkAUKjJK.jpg)
Karsten Suhre on Twitter: "@mims Does a programmable calculator count? Then it was a TI-58. But the oldest one I used was actually a Telefunken TR440 mainframe, running FORTRAN IV abd SPSS
Texas Instruments Exactra 20 Handheld Electronic Calculator (TI-20) | National Museum of American History
![Calculator Portable 20 Keys Multifunctional 10 Digital LCD Calculator for Student Office Mechanical Buttons,Pink - Walmart.com Calculator Portable 20 Keys Multifunctional 10 Digital LCD Calculator for Student Office Mechanical Buttons,Pink - Walmart.com](https://i5.walmartimages.com/asr/55cb8cfb-9b3a-4e5c-9a30-5f98967d7110.4182fe38ee950a8b4d8dc7a490f05a5f.jpeg)
Calculator Portable 20 Keys Multifunctional 10 Digital LCD Calculator for Student Office Mechanical Buttons,Pink - Walmart.com
![4-20 mA Current loop - Calculation of process variable - Field Instrumentation - Industrial Automation, PLC Programming, scada & Pid Control System 4-20 mA Current loop - Calculation of process variable - Field Instrumentation - Industrial Automation, PLC Programming, scada & Pid Control System](https://forum-automation-uploads.sfo3.cdn.digitaloceanspaces.com/original/2X/3/3ff3f71d734a0a6f7436f63b532a06aac0690bfb.png)
4-20 mA Current loop - Calculation of process variable - Field Instrumentation - Industrial Automation, PLC Programming, scada & Pid Control System
![Calculator Portable 20 Keys Multifunctional 10 Digital LCD Calculator for Student Office Mechanical Buttons,Pink - Walmart.com Calculator Portable 20 Keys Multifunctional 10 Digital LCD Calculator for Student Office Mechanical Buttons,Pink - Walmart.com](https://i5.walmartimages.com/asr/1acf92a7-7419-4f89-94de-095310ba5008.ca380fb8c56e35503aea0084753ed098.jpeg?odnHeight=612&odnWidth=612&odnBg=FFFFFF)