Difference between revisions of "EDSAC"
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(only 7 more to add, already noted a possible error in source doc) |
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| H n || Copy the number in storagae location n into the multiplier register | | 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 | + | | 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 | + | | 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 | | T || Transfer the contents of the accumulator to storage location n and clear the accumulator | ||
|- | |- | ||
| − | | *Z | + | | 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<sup>-1</sup> | ||
| + | |- | ||
| + | | ** R 2<sup>p-2</sup> F || Shift the number in the accumulator p places to the right; that is, multiply it by 2<sup>-p</sup> (2≤p≤12) | ||
| + | |- | ||
| + | | R F || Shift the number in the accumulator 15 places to the right; that is, multiply it by 2<sup>-15</sup> | ||
| + | |- | ||
| + | | * L F || Shift the number in the accumulator 1 place to the left; that is, multiply it by 2 | ||
| + | |- | ||
| + | | ** L 2<sup>p-1</sup> F || Shift the number in the accumulator p places to the left; that is, multiply it by 2<sup>p</sup> (2≤p≤12) | ||
| + | |- | ||
| + | | L F || Shift the number in the accumulator 13 places to the left; that is, multiply it by 2<sup>13</sup> | ||
| + | |- | ||
| + | | * Z || Stop the machine | ||
|- | |- | ||
|} | |} | ||
| − | *The addresses in these order codes need not be zero. | + | * The addresses in these order codes need not be zero. |
| − | ** The addresses in these orders may be k.p- | + | ** The addresses in these orders may be k.2<sup>p-1</sup> where k is odd, provided that the addresses do not exceed 2047. |
Revision as of 22:59, 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 |
| * 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.
