This paper describes the introduction of advance repeat facilities - the duplication of frames. As it makes use of basic files to save each frame, it has the restrictions that only those devices whose orders may be saved in basic files can be used, and only one such device may be selected at a time. It could also cater for devices with hardware repeat features.
Two routines are available:
ADVRPT (X)
and a display routine:
ADVCNT (X)
ADVRPT sets up the advance repeat mechanism. If X>0.0, each frame will be repeated X times. X=0.0 will remove the mechanism. ADVCNT can be used in a file, and can change the number of repeats. However, ADVRPT must be used to set up and remove the facility.
ADVRPT calls STSAV to set up a basic file for the currently selected device. There may only be one device selected, and this device must be capable of using basic files. Also, no other file definition is allowed while advance repeat is in operation. Any devices selected subsequently will only receive single frames.
All output for the selected device is stored in the basic file until ADVFLM is met. FISAV is called to close the file, and the contents are output the required number of times, interspersed with advance frame orders. The file is restarted by another call to STSAV, which will re-use the space.
ADVRPT (0.0) will call FISAV to close the file, and then DLETE to remove the file altogether. The file is given the name
X...
The method described here will work for the SD4020, whose advance repeat hardware is suspect. However, the facility could be extended to lineprinter graphical, and to any device with suitable hardware, without using basic files. Since lineprinter graphical is designed as a debug aid only, it is not intended to implement this facility for this device.