User manual QUANTUM SCALAR 218 THEORY OF OPERATION

[. . . ] While executing the Boot Code, the Main Processor checks to see if the Flash Memory contains valid operating code (operational firmware). If the operational firmware is valid, the Main Processor signals to the Motion Processor to notify the keyboard and then proceeds to download code from the Flash Memory to the Motion Processor's RAM. When completed, the Main Processor signals the Motion Processor to switch to RAM-based code and then switches its addressing so that it begins operating out of the Flash Memory instead of it's internal Boot ROM. If valid operational firmware is not found in the Flash Memory, the Main Processor continues to execute the Boot Code, monitoring the SCSI chip for a valid request to download code to the Flash Memory. [. . . ] Monitors the gripper limit signal which indicates that the jaws have stalled or reached a limit. Controls the enable, direction, and break of the roller motor. Controls the enable, direction, and break of the carriage motor. Controls the trigger on the Barcode reader and monitors the serial Barcode reader data. 3 l l l adic Service Procedure 63-1181-01 Rev A Scalar 218 Theory of Operation Micro-Stepper Processor The Micro-Stepper Processor takes high level movement commands and breaks them down into finite steps of the X Stepper Motor. The four finite motor steps, are displayed on the four diagnostic LED's. The four digital steps are broken down further into 16 sub-steps. These sub-steps are of variable amplitudes such that the resultant waveform of a full step approximates a sine wave. The MicroStepper Processor controls the following: l l l Quad output D to A converter. Data input and output registers. Door Open Stepper Motors Each drive assembly employs a door over the drive cartridge opening. This door must be physically opened or closed to load or unload a cartridge. Damage to the drive and/or media will occur if the door is opened or closed while the drive is still loaded (the tape is still wound through the read/write head mechanism). To prevent damage to the drive and media, the drive illuminates an Operate Handle LED on its front panel to indicate when it is unloaded (the tape is fully rewound into the cartridge). When the Operate Handle LED is illuminated the drive assembly outputs an "OK to Open Door" status message via its serial port. To automate the insertion and removal of cartridges the 218 employs a Door Open Stepper Motor that rotates the door's hinge shaft, thus opening or closing the door. This Door Open Stepper Motor is mounted on the drive assembly's drive mounting plate directly above the drive. The Controller Section monitors each of the drive assembly's serial port, via the Drive Mux Bus, and opens or closes the door when the "OK to Open Door" status message appears. adic Service Procedure 63-1181-01 Rev A 4 Scalar 218 Theory of Operation Media Handling Mechanism This section controls all movement of media within the 218. It is used to pick and place media between the DLT drives and the 18 cartridge locations. The Media Handling Mechanism components include the Media Picker, X Stepper Motor, X carriage, carriage rails, and associated drive belts and sensors. Media Picker Entry/Exit Port The pass-through Entry/Exit Port allows the Media Picker to pick or place data cartridges from/to the storage slots and drives without needing an additional media handling mechanism or having to rotate a cartridge. Cartridge Sensors are mounted in both openings of the Entry/Exit Port. These sensors monitor the position of the data cartridge. If the cartridge is not fully positioned in the Cartridge Gripper Assembly, the Picker Processor informs the Main Processor via the Motion Processor. [. . . ] The contents of the 218 (inventory) can quickly be determined by polling these sensors. Door Open Sensor The sliding access door open sensor alerts the Motion Processor of the door's position (opened or closed). If the door is opened during On-Line Mode operation, a SCSI UNIT ATTENTION message is sent to the host. It is up to the software application running on the host to handle this condition with the proper routine. If the door is opened while the 218 is performing a pick and place operation, the Motion Processor automatically causes all Media Picker motion to stop. Drive Assembly Section One or two drive assemblies may be mounted in the Drive Assembly Section. [. . . ]