First Time Booting Up: "?SN Error"

[K Skruber]

I just assembled an RC2014 Mini and connected (and powered) via FTDI cable to my mac running the program Serial (set the right baud rate etc). 

My terminal shows the "Z80 SBC By Grant Searle" text but then after that line it says 

?SN Error

I have an oscilloscope and my clock signal looks good. I checked all of my solder connections with a multimeter in conductivity mode. I made sure that each VCC pin for each of the chips is reading 5V. I also got approx 2.2 on the clock pin. When I hit reset the 5V on the reset line goes low, so I know that it's resetting properly. 

Any ideas what's going on? SN Error looks like it's throwing a BASIC issue. 

Thanks in advance, screen shot of the terminal error attached.

[Richard Kiernan]

According to the BASIC manual, "?SN Error" refers to a syntax error. I'm seeing the 'K' and 'C' characters below the "Ok" response and I'm wondering if there are some junk characters being sent across when you're doing the reset somehow. Are you able to enter characters after that and do they show up normally?

[Spencer Owen]

My suspicion would be something to do with the RAM. Or possibly the high (A15) address line.

The ROM appears to be ok. The CPU is obviously running fine, as is the UART and clock. If any of those weren't working then you wouldn't get any output at all.

I'd suggest touching up the joints on the 62256 chip and see if that helps. If not, use a multimeter in continuity mode, and check off the address lines between the CPU and RAM from the chips themselves (not solder pads underneath) according to the schematic.

Also worth trying SCM on the ROM, which you will need to move all the jumpers to the 1 position to access. I doubt that will give any different results but if you have a Digital I/O Module then that might give you a light display as it boots up.

Spencer 

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