Debugger General Information
Disk I/O via 197Bug System Calls
All operations that actually access the disk are done directly or indirectly by 197Bug TRAP #496 system calls. (The
3a convenient way of using these system calls without writing and executing a program).
The following system calls are provided to allow user programs to do disk I/O:
.DSKRD | Disk read. System call to read blocks from a disk into |
| memory. |
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.DSKWR | Disk write. System call to write blocks from memory onto a |
| disk. |
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.DSKCFIG | Disk configure. This function allows the user to change the |
| configuration of the specified device. |
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.DSKFMT | Disk format. This function allows the user to send a format |
| command to the specified device. |
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.DSKCTRL | Disk control. This function is used to implement any special |
| device control functions that cannot be accommodated easily |
| with any of the other disk functions. |
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Refer to the MVME197BUG 197Bug Debugging Package User’s Manual for information on using these and other system calls.
To perform a disk operation, 197Bug must eventually present a particular disk controller module with a controller command packet which has been especially prepared for that type of controller module. (This is accomplished in the respective controller driver module). A command packet for one type of controller module usually does not have the same format as a command packet for a different type of module. The system call facilities which do disk I/O accept a generalized
The packets which a controller module expects to be given vary from controller to controller. The disk driver module for the particular hardware module (board) must take the standardized packet given to a trap function and create a new packet which is specifically tailored for the disk drive controller it is sent to. Refer to documentation on the particular controller module for the format of its packets, and for using the IOC command.
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