EDSAC

Conceived in 1946 and the machine did its first calculation in the summer of 1949

Order Codes

Order	Description
A n	Add the number in storage location n into the accumulator
S n	Subtract the number in storage location n from the accumulator
H n	Copy the number in storagae location n into the multiplier register
V n	Multiply the number in storage location n by the number in the multiplier register and add the product into the accumulator
N n	Multiply the number in storage location n by the number in the multiplier register and subtract the product into the accumulator
T	Transfer the contents of the accumulator to storage location n and clear the accumulator
U	Transfer the contents of the accumulator to storage location n and do not clear the accumulator
C	Collate the number in storage location n with the number in the multiplier register and add the result into the accumulator; that is, add a "1" into the accumulator in digital positions where both numbers have a "1" , and add a "0" in other digital positions
* R D	Shift the number in the accumulator one place to the right; that is, multiply by 2-1
** R 2p-2 F	Shift the number in the accumulator p places to the right; that is, multiply it by 2-p (2≤p≤12)
R F	Shift the number in the accumulator 15 places to the right; that is, multiply it by 2-15
* L F	Shift the number in the accumulator 1 place to the left; that is, multiply it by 2
** L 2p-1 F	Shift the number in the accumulator p places to the left; that is, multiply it by 2p (2≤p≤12)
L F	Shift the number in the accumulator 13 places to the left; that is, multiply it by 213
E n F	If the number in the accumulator is greater than or equal to zero, execute the next order which stands in storage location n; else proceed serially
G n F	If the number in the accumulator is greater than zero, execute the next order which stands in storage location n; else proceed serially
I n	Read the next row of holes on the input tape and place the resulting integer, multipled by 2-16, in storage location n
O n	Print the character now set up on the teleprinter and set up on the teleprinter the character represented by the five most significant digits in storage location n
F n	Place the five digits which represent the character now set up on the teleprinter in the five most significant digits in storage location n, clearing the remainder of this location
* X	Ineffective; machine proceeds to the next order
* Y	Round-off the numberin the accumulator to 34 binary digits; that is, add 2-35 into the accumulator
* Z	Stop the machine

*  The addresses in these order codes need not be zero.
** The addresses in these orders may be k.2p-1 where k is odd, provided that the addresses do not exceed 2047.