Difference between revisions of "EDSAC"
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| L F || Shift the number in the accumulator 13 places to the left; that is, multiply it by 2<sup>13</sup> | | L F || Shift the number in the accumulator 13 places to the left; that is, multiply it by 2<sup>13</sup> | ||
| + | |- | ||
| + | | 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<sup>-16</sup>, 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<sup>-35</sup> into the accumulator | ||
|- | |- | ||
| * Z || Stop the machine | | * Z || Stop the machine | ||
Revision as of 22:17, 18 May 2007
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.
