I've been running so hard that, as I've been typing this up, I've been trying to get the sketch to upload to the Arduino Nano for final assembly.

Looks like the cable I'e been using isn't good enough for Arduinos... works fine on my MiniDisc player! (It's an old USB Mini-B cable.) Either that or I've got gremlins... knowing me, it's gremlins :(

It's now 12:11 AM on the West Coast as I type this. I'm late...

/sigh

I'm trying not to cry. Judges, please have mercy on me, I promise I'm doing my best...

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EDIT 03:18 AM Eastern / 12:18 AM Pacific --

It's gremlins :( heaven only knows what freaking bootloader this dang board has, but it's not the standard Nano bootloader. So I'm having to guess... literally I get to brute-force guess through the list of possibilites.

So far I've worked out that it's not an Uno bootloader, a Nano bootloader, a Duemilanove/Diecimila bootloader... next is the Arduino Mini (the old one), then the Arduino Pro / Pro Mini (which is, oddly, stuck into the "Arduino AVR Boards" section, now, and not "Sparkfun AVR Boards", even though it's a Sparkfun part...), *then* the Sparkfun Redboard, their "Qduino Mini", and finally the RedBot mainboard entry.

If *none* of those work, it's off to eBay to see what currently ships, although this was a secondhand board that someone gave me, and it's been literally aging in the back of a drawer somewhere in their basement fiddle-spot for even they don't know how long, so... :-/ yikes.

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EDIT #2 - 03:54 AM Eastern / 12:54 AM Pacific --

You have GOT to be freaking kidding me. Apparently ANY wire connected to D0 (Digital Pin 0 aka RX) will screw up the upload process. That pin, although it's strictly speaking not used in the sketch as written, *does* have a lead going to the HIN232CP chip to enable return communication from the printer. I fired up the old Hakko 926 and pulled the wire loose... no difference at first. Then I tried setting it to "Old Bootloader" -- and it uploaded.

/sigh

This is a *direct* clone of the original. No crazy Chinese cost engineering here... not yet, that didn't really happen till the Pro Mini / Pro Micro clones came out. You'd think s--- like this would be designed better than that...

You'd think...

/sigh