[Mark1960]

I have extra memory added to my MK14 now though only tested with a single processor so far. I’ve used point to point wiring on soldered proto board. Uses a header to connect into the SCMP socket on the MK14, with a socket to take the SCMP. This is then connected to an AS6C4008, but only 32K is available as 16x2K blocks filling the low 2K of every 4K page. Using a 74ls395 to latch the page address.

The RAM is battery backed using a MAX818, which also provides reset to the SCMP, though this is not able to reset the 8154. The reset input from the MK14 is connected to the watchdog input of the MAX818 via a schottky diode, so a manual reset can be performed by holding the MK14 reset for more than 1.6 seconds.

The RAM was initialised with read enable disconnected and connecting write enable to NRDS. Then the MK14 is connected and exercise the various functions of the monitor. Each instruction executed is then written to RAM. Then the MK14 proms are removed, read and write enable of the RAM connected. Then on power up the monitor seems to be running from RAM.

Its a bit of hassle to bootstrap if the ram is corrupted but was just an experiment to see if it would work.

I still need to run a proper ram test to make sure everything is working properly.

I’ll add some pictures and a schematic when I get my laptop fixed or everything installed on the new one, priority was to get the laptop running for work related software first.