At a certain point in the 1980s, 'I' things were all the rage in DEC.
BI - Backplane Interconnect (the bus in the 8xxx series VAXen - see Wikipedia)
CI - Computer Interconnect (showed up as star coupler for VAXclusters, also to HSC intelligent storage controllers)
NI - Network Interconnect (ethernet to you).
SI - Storage Interconnect - controller-to-disk.
I can give you an anecotal answer. I did this a few times.
I suspect that porting in this direction would have been unusual. We only did it where the customer insisted on the use of Vax hardware.
The company I worked for for many years specialised in real-time process control and communications handlers. We made our own range of controllers, based on the ...
I was VAX Architect for six years in the late '80s, and at least during my tenure, Raytheon was the only company licensed to design VAX-compatible processors, for producing MIL-SPEC machines. They did design at least one (a high-performance processor with a very interesting microarchitecture that translated VAX instructions on the fly into a RISC-like ...
In answering this question, I found that there were multiple generations of 11/780 memory board, and so sizes, capacity, etc., are quite hard to pin down. I still have not found a board larger than 4MB.
I did get an answer for physical board size, though not for slot width (board separation).
One MS780 memory controller can take 16 memory array boards. ...
From the DECUS VMS Fortran source, the random routine RND() is as follows:
IF (SEED.EQ.0) CALL SYS$GETTIM(TIME)
According to David Deley's How Computers Generate Random ...
Note: Strictly speaking, my answer below doesn't answer the question asked, because what the OP was referring to was the instructions reserved for customer use, rather than those it reserved for DEC, which is what my reply was about. The corrected version of my answer, for the "XFC" opcodes (with a prefix of hex 0xFC) would be not as far as I ...
To give you a sense of the inter-board spacing in these types of systems, it is useful to consider the main constraints. These include airflow for cooling, the physical space between the connectors on the backplane and component height.
The gap for airflow purposes was such that most folk could slide their fingertips between boards, but only at the expense ...