On Sun, Dec 28, 2008 at 4:07 PM, Dave McGuire <mcguire at neurotica.com> wrote: My curiosity is piqued. If the mods are really extensive, I may never try it, but it would be interesting to learn what's involved. ISTR there were some 4MB "cache" boards for the 11/70 that one could use in place of the MK11, but I doubt that it would be easy to find a loose one these days. -ethan

On Dec 28, 2008, at 1:07 PM, Dave McGuire wrote: The easiest thing to do would be to replicate a PEP-70. It's fairly easy as it would be one hex board with all of the memory. The only modification needed for the 11/70 is 4 power jumpers to slot 19. Then just route short cables from the cache boards to the new board rather than to the external memory boxes. I wouldn't run an 11/70 any other way. :-)

There aren't any schematics, but the installation manual is on bitsavers. If I were to do it, I'd look at the cache interface going to the MK11 and just build a board that interfaces to that. Putting the memory on with an FPGA to do all of the timing/interfacing shouldn't be too hard. I'm doing something similar for regular Unibus memory + ROMs + KW11L + 2 SLUs . It's basically it's an FRAM, FPGA (Spartan 3E), level shifters (3.3v to/from 5v) and Unibus transceivers. All of the work is in the FPGA written in verilog. It shouldn't be hard to do something similar to emulate a full set of MK11 memory to the cache interface (probably using high density SRAM rather than FRAM). Depending upon the density of the SRAM(s) it might even be possible to do it as a quad board vs hex. The only thing coming from the 11/70 backplane is power and ground (for slot 19). All signaling is from the ribbon cables connected to the cache boards (4 cables). TTFN - Guy On Dec 28, 2008, at 3:50 PM, e.stiebler wrote: