This sets or clears the carry flag depending on whether the escape key is pressed or not.
Once an escape condition has been detected, (either through this or for example, with OS_ReadC), it should be acknowledged with OS_Byte 126 or cleared using OS_Byte 124.
This call is useful if a program is executing in a loop which the user may want to escape from, but isn't performing any input operations which would let it know about the escape.
Note that this may be called from an interrupt routine. However, OS_Byte 126 may not be, so if an escape is detected under interrupts, the interrupt routine must set a flag which is checked by the foreground task rather than try to acknowledge the escape itself.
See PRM 1, page 912.
[sh-index] Back to list of manuals
|
| |
