*************************** * * * Usage of CAT3 Cards * * * *************************** 14-JUL-1992 There are several places where CAT3 cards are used in the First Level Calorimeter Trigger. The CAT3 card must be properly configured for its environment. This file describes the various CAT3 environments and associated configurations. Tier 3 of the Energy Adder Trees -------------------------------- In the Third Tier of the Energy Adder Trees, the CAT3 is expected to add five, 15-bit unipolar operands. There are 10 Tier 3 Energy Adder Tree CAT3 cards, used as follows: Quantity Description -------- ----------- 4 EM Energy 1st Lookup 1 EM Energy 2nd Lookup 4 HD Energy 1st Lookup 1 HD Energy 2nd Lookup All of these cards must have some negative number stored in the Correction Register for pedestal removal. In some cases, all of the pedestal is removed, and in other cases 200 counts of pedestal is allowed to remain. It is important that the Correction Register operates 100% correctly in all of these cards. These cards should be configured as follows: Each of the 7 jumpers may be installed or not installed in the "standard" place. The bits affected by the jumpers are never exercised in the Energy Adder Tree CAT3 cards. The value loaded in the correction register should be either the 2's complement of the global pedestal offset for the type of tree serviced by the CAT3 card, or the 2's complement value of 200 less than the global pedestal offset for the type of tree serviced by the CAT3 card, depending on how much of the pedestal is to be removed on that particular CAT3 card. Finally, note that the same input cables feed all 5 cards of each energy type (4 1st Lookup and 1 2nd Lookup). This means that the terminator and spreader resistors of all but 1 card of each energy type must be removed. Note that all input operand bits of a given value are connected in parallel on all 5 cards. This means that the un-driven high order operand bit (bit 16) on all operands on all cards will still be "spread" to a good safe legal state by the un-removed spreader resistors. The spreader and terminator resistors will be removed from all but the last card on each cable. For EM Energy, the terminators and spreaders will NOT BE REMOVED on the card corresponding to the First Lookup, Thresholds 0..3. For HD Energy, the terminators and spreaders will NOT BE REMOVED on the card corresponding to the Second Lookup, Thresholds 0..3. Following is a table which describes the cabling and pedestal removal for each CAT3 Card. Pedestal Card Description Removal Cabling ---------------- -------- ------- EM 1st Lookup Thr 0..3 All Final Sum to IMLRO EM 1st Lookup Thr 4..7 All but 200 F.S. to T4 Tot LU1 EM 1st Lookup Thr 8..11 None ? nowhere for now EM 1st Lookup Thr 12..15 None ? nowhere for now EM 2nd Lookup Thr 0..3 All but 200 F.S. to IMLRO and T4 LU2 HD 1st Lookup Thr 0..3 All Final Sum to IMLRO HD 1st Lookup Thr 4..7 All but 200 F.S. to T4 Tot LU1 HD 1st Lookup Thr 8..11 None ? nowhere for now HD 1st Lookup Thr 12..15 None ? nowhere for now HD 2nd Lookup Thr 0..3 All but 200 F.S. to IMLRO and T4 LU2 Tier 3 of the Momentum Adder Trees ---------------------------------- In the Third Tier of the Momentum Adder Trees, the CAT3 is expected to add three, 15-bit unipolar operands and three, 16-bit "signed" operands. The three "signed" 16-bit operands are actually the one's complement of 15-bit unipolar numbers. The 16th bit of the unipolar operand is guaranteed to be low, so the 16th bit of the 1's complement of the unipolar operand is guaranteed to be high. There are 2 Tier 3 Momentum Adder Tree cards, used as follows: Quantity Description -------- ----------- 1 Px Adder 1 Py Adder Each of these cards is to have the value 3 stored in the Correction Register. There is no pedestal to be removed, as the pedestal is symmetric for +Px/-Px and +Py/-Py. The value 3 is used to effectively convert the three 1's complement input numbers into three 2's complement input numbers. Recall that the 2's complement is really the 1's complement plus 1. The jumpers should be configured as follows: the jumpers for the 1st and 2nd stage adders corresponding to the 3 "positive" inputs can be either installed or not installed. The bits corresponding to these jumpers are never exercised. The jumpers for the 1st and 2nd stage adders corresponding to the 3 "negative" inputs must be installed in the standard locations. Finally, the jumper for the partial sum output must be installed in a NON-STANDARD location. The jumper was intended to jumper the 19th bit to the 20th through 24th bits. Instead, the jumper must connect the 18th bit to the 19th through 24th bits. This is a direct extension of the fact that 2 M-bit 2's complement numbers, when added, produce again an M-bit 2's complement number. Tier 4 of the Energy Adder Trees -------------------------------- In the Fourth Tier of the Energy Adder Trees, the CAT3 is expected to add two, 18-bit unipolar operands. There are 2 Tier 4 Energy Adder Tree cards, used as follows: Quantity Description -------- ----------- 1 Total Et Adder 1st Lookup 1 Total Et Adder 2nd Lookup For these cards to operate 100% correctly, with no truncation between Tier 3 and Tier 4, the inputs of the card need to be altered.