Product Description

The essence of the Hytec system Crate, which grew out of the Rutherford Laboratory multi–crate, multi–source design, is explained in our document “Configuring CAMAC System Controllers”. An Executive Controller is an essential feature of the System Crate, being its control and arbitration unit: it occupies the right–hand two stations of any CAMAC crate (thereby converting it to a System Crate) and may be the standard unit, MX–CTR–3 or the ACB Master MX–CTR5. There is also one that contains a full System Crate Q–bus interface, the Exec 1100 (still only 2 widths) which has its own data sheet.

System Crate Operation

When one of the possibly many Program Sources in the System Crate is triggered to do a CAMAC cycle, it applies on the rear–panel 4–line Arbitration Highway for permission to do so: this works on a normal Request–Grant principle. The successful Program Source then puts the target module Branch, Crate and Station Number (BCN) address onto the Write lines, with F and A on their normal lines, and the Executive Controller EITHER produces dataway Busy (signalling to the program Source to remove BCN from the Write lines together, to do a System Crate cycle, which is experienced by a normal user module exactly as specified in IEEE583/EUR4100, OR it selects the addressed (Serial or Parallel) Branch Coupler and enters the appropriate sequence. This is described in the data sheet for BR–CPR4–1 (parallel) or EC505 (serial). In any case all this is quite transparent to the user, who gets the effect of remote CAMAC modules being mapped into the System Crate without having to handle any special protocol.

Detailed Data

The use of W lines in the temporary way described above is shown in Table 1, while Table 2 gives the addressing used for driving Branch Couplers. The function Set of the Executive Controllers is exactly as for Type A crate controllers, (Table 3) as in the pin–out for the rear–panel 52–way DD LAM Grader Plug.

MX-CTR-4

All the above applies to all three Executive Controllers in this data sheet. In addition the MX–CTR–4 carries all 23N and 23L lines (and S1, S2 and Busy) to a single width System Crate Extender module in station 25 of a second crate. patch links there allow N and L lines unused in the main System Crate to be used in this second crate. For example, the time–sharing manual controller SC–TST–1 is 3 widths, but only uses one N; the other two that it occupies can be transferred for use in the second crate. This is very useful for unusually complex system controllers.

MX-CTR-5

As mentioned earlier, this unit is a standard ACB Master as well as having all the characteristics of the MX–CTR–3. It is particularly useful when a high–speed front–end processing Auxiliary Controller complements the System Crate. To provide the flexibility to accommodate possibly different System Crate and ACB timing requirements, switches are provided for many functions. On board 1, SW1 enables the Indirect Data Channel facility (see the System Crate Philosophy document) while SW2 Enables Encoded Ns to be gated with Auxiliary Controller Busy: on Board 2, SW1 controls the CERN–specified ’HOLD’ function, and switch ’n’ (1–8) of SW3 allows the System Crate to ’grab’ 2 n–1 cycles, in the absence of ACL, before allowing Grant to be passed on to any Auxiliary Controller. For SW2 of board 2, switch 1 allows the SC continuously to do cycles so long as SC Request is present and ACL absent; switch 3 selects R/G or ACL mode; switch 4 connects the Executive Controller Watchdog to LAM at Station 23; switches 5 and 7 force SC cycles to be aborted on receipt of ACL before S1 for Branch and System crate respectively; and switch 6 links Request internally to Grant In for use when the MX–CTR–5 is not sharing the ACB with any Auxiliary controllers.

Auxillary Controllers