Improved Buffering for Printer Device Driver
Original Publication Date: 1986-Apr-01
Included in the Prior Art Database: 2005-Mar-08
A method is described to improve the intermediate buffering of data to a device by using large buffers of varying lengths. In the UNIX*-operating system, device drivers for character devices such as printers, must sometimes copy data to intermediate internal buffers before outputting the data. The intermediate buffers consist of many small fixed blocks of memory, each 64 bytes long. These blocks are collectively referred to as character lists. The UNIX operating system runs as a virtual machine on the Virtual Resource Manager (VRM) control program. the VRM control program is similar in concept to the IBM VM/370 control program. The VRM and UNIX run in a virtual memory environment. The kernel device driver requests an output operation with a supervisor call (SVC) to the VRM.