PDP-11 front-end for a VAX-11/780
Michael Browne, C Granieri, D. J. Sherden, L.J. Weaver · University of North Texas Digital Library (University of North Texas) · 1980
An unpublicized feature of the VAX-11/780 is the provision for attaching a PDP-11 to the VAX UNTBUS Adapter.This can givr significant1.yimproved J/O performance for applications which are limited by overhead in the VAX I/O driver rather than by the transfer speed of the UNIBUS itself.We have implemented such a system using a PDP-11/04 as a "front-end" to a CAMAC data acquisition system.Both the PDP and the VAX have full access to the UNIBUS.That portion of the PDP address space which does not have UNIBUS memory can be mapped to buffers in the VAX memory, allowing the PDP to access VAX memory and to initiate DMA transfers directly to the VAX.The VAX also has full access to the PDP memory, providing a convenient means for developing and downloading the PDP software.