This weekend I’m spending at the lake, so I’m nowhere near the Horizon (849km away according to Google), but I had a small flurry of success just before I left, and I have a few minutes relaxing by the bonfire with a drink in hand, so I might as well grab the photos from my phone and bring my project up to date.
I pulled out my trusty VT220 and hooked it up. At this point, all I have in the backplane is the CPU board with the boot PROM. There is no RAM yet, but according to the documentation for the monitor ROM, it operates with no need for RAM – which is very handy for testing. My motherboard is strapped for 9600 baud, so I set the terminal to the same speed, and I power everything on.
A prompt! Well, not right away – I had to exchange my serial cable for a null-modem cable, but then – a prompt! The ‘]’ symbol is the appropriate prompt for this monitor. No fancy sign-on bender (what was I expecting for a 1K monitor?)
I can examine memory (everything is FF except for the 1K of monitor ROM), and depositing doesn’t change anything, but it’s working! What does this success tell me? It tells me that the serial port is working (and if the serial port is working, reading and writing to I/O ports is also working). The address and data busses are also working. This makes me happy!
As I have mentioned previously, the biggest challenge I’m going to face with this project is the lack of any NorthStar memory boards. The machine didn’t come with any, but I did acquire a Dynabyte 64k memory board of unknown operational status. I made a request last week on some mailing lists, and amazingly I was able to find someone willing to part with two 32k Northstar memory boards – and the amazing part was they were located in Kelowna! I grabbed them (and a nice S100 extender card) just before I left for the lake, so I can’t wait to get back and test them out!