EDVAC (Electronic Discrete Variable Automatic Computer) was one of the earliest computers in the world. It was built in Pennsylvania, Moore School of Electrical Engineering, by John Presper Eckert. ENIAC inventors, J. Presper Eckert proposed the EDVAC’s construction to the Ballistic Research Laboratory in 1944. An agreement to build the new computer with an initial budget of $100,000 was signed in April 1946. EDVAC was delivered to the Ballistic Research Laboratory in 1949.In 1952, the Ballistic Research Laboratory became a part of the US Army Research Laboratory. It was next in line to ENIAC, worlds first general purpose computer, along with ORDVAC. ENIAC used decimal while EDVAC used binary and it was designed to be a stored program computer. EDVAC was in service until 1962 when it was replaced by BRLESC.
EDVAC was a binary serial computer with automated multiplication, addition, subtraction and automatic checking with an ultrasonic serial memory consisting 1,024-44 bit words, thus giving a memory of 5.6 kilobyte in modern terms. EDVAC was a dual memory device with two sets of 64 mercury acoustic delay lines, each with eight words of capacity.
At 1,160 operations per second, EDVAC’s average addition time was 864 microseconds, while its average multiplication time was 2,900 microseconds (about 340 operations per second). The length of time required to complete an operation was determined by the memory access time, which changed based on the memory address and the moment in the serial memory’s recirculation cycle.With 12,000 diodes and 5,937 vacuum tubes, the computer used 56 kW of power. It had a floor area of 490 feet (25.5 metres) and weighted 17,300 pounds (8.7 short tons; 7.8 t).  Thirty employees might work an entire eight-hour shift as operating staff.
Floating-point calculations were also possible with EDVAC. It employed one bit for its sign and 33 bits for the mantissa. The sign bit was one of the ten bits utilised for the power of two.The 44-bit word was split into four 10-bit addresses for executable instructions and four bits to encode the index of an operation. The first two addresses pointed to the memory locations of the numbers used in the operation, the third address to the region in memory where the result would be stored, and the fourth address to the location of the instruction that would be performed after that. Of the 16 potential instructions, only 12 were actually used.
Effect on Future Computer Architecture
First Draft of a Report on the EDVAC, John Von Neumann’s renowned EDVAC monograph, outlined the primary change to the device’s design that realised the key “stored-program” idea that we now refer to as the Von Neumann architecture. This involved keeping the software and data in the same memory. The first operational computers that used this design were the British machines EDSAC at Cambridge and the Manchester Baby. And the vast majority of computers created afterwards have followed suit. As identify it, the Harvard architecture is now referred to as having the programme and data in separate memory.