Within this era there were many computers being developed, however they were very early models and could be considered primitive to anyone looking back on it today. However, at the time they were some of the highest class machines that one could use for computing numbers and using as advanced and complex calculators.
Z1 Computer - 1936
The Z1 was a computer designed by Konrad Zuse in 1936, making it the first freely programmable computer, even though the extent to which one could program was limited. It functioned as a calculator and it contained a control and a memory for calculating. Because there were no monitors at the time, it used a punched tape reader to show the output of a given function.
Atanasoff-Berry Computer (ABC) - 1940-1942
This computer was the first binary computer and was developed by J.V Atanasoff and Clifford Berry. It had parallel processing and regenerative memory which meant it was the first computer to be able to store information on its own main memory. The computer was only designed to solve systems of linear equations. It wasn't programmable but it could solve up to 29 equations at the same time.
UNIVAC - 1951
This was one of the first commercially available computers and was used by many companies to manage basic arithmetic such as cost, expense, supply, etc. It was primarily developed by John Eckert and John Mauchley in 1951 for the US Census Bureau to allow for simpler handing of large amounts of data. This was a big change from the punch card systems that were formerly used.
FORTRAN - 1954
Even though this isn't exactly a computer, it was one of the first advanced programming languages that was made for computers. The creator was John Backus and the language specialized in making calculations and using numbers.
Integrated Circuits (Computer Chip) - 1958
This was a turning point in computer history because it allowed many operations to be preformed in a much smaller area. Without this computers would still take up entire rooms.