tjc (07/02/82)
Wanted: information about the problem with Floating Point emulation on the 11/70 with split I/D programs due to the wierdness of DEC's MFPI instruction. The normal FP emulation on an 11/70 without floating point hardware will not work on a split I/D process because the MFPI required to get at the trapping instruction (so it can be properly emulated) gets data from the data space instead of instruction space. DEC claims this is correct (?). I am aware of at least two possible fixes for this problem. One involves a simple back-plane wire change; the other involves modification of the kernel to get at the instruction directly. Does anyone have details (or pointers to details) about either of these two solutions? Please respond by mail. Tom Cook Bell Labs, Columbus cbosg!tjc