sheesh, now Goodwill is making a habit of having one of these calcs on the shelf. This time a TI-84 Plus. I don't need another, do I? I haven't seen the 82 I got in middleschool in maybe a year. I think it wound-up in storage. The 83 plus(?) I got last time I decided to keep in arm's reach for calculations. But, somehow haven't seen since. While, of course, the 86 is my hacking-machine...

The 84Plus appears to be z80-based, as well. Like the 83Plus it has flash memory which can store user stuff, from what I gather... but, it also has USB-OTG(?!) On a z80(?!). Folk've made drivers for mice, keyboards, gamepads, and even USB thumb drives. Crazy. USB hosting ain't an 8bit thing, I thought...

But... I don't really know what I'd do with it.

Still, what was it... $7? How could I refuse?!

Maybe if it's still there next time.

Thing is, these don't use the same z80 VLSI, so it'd be a whole new platform to learn, as far as hardware hackery... i tend to learn the ins and outs of one thing, then try to push its limits... writing software ain't /really/ my jam so much as it's a tool to make my weird hardware ideas work. So, in the realm of calculator-hackery, i guess most my stuff will likely be limited to the '86, and plausibly the 85 and 81, which share the same processor VLSI. Though, realistically, it's kinda hard to imagine the other z80-based calcs' architectures vary too dramatically... so it /could/ be a curiosity to see what the others are like, and whether what I've come up with can be ported. So far, though, I think my work mostly amounts to figuring out a few of the T6A43 z80 VLSI's undocumented features, and adding Flash... which... of course... doesn't apply, and is redundant, respectively, on the other calcs. 

So, all this to say... it was hard to turn down that 84Plus at 7bux... but I managed to convince myself this time.

...

On another note, I picked up an x86-compatible "pico-ITX" which has a real serial port... so may consider moving on from the PiZero based computer I've been using...

(Heh, I bet I coulda bitbanged its GPIOs for the graphlink, now that I think of it. Sheesh. But, I dunno how many if any are free, since I'm using them for the DPI display... and, well, it'd be a whole other realm of programming a new tilp connection library... which would probably be far too niche for anyone else to be interested in...? Though, linux's gpio drivers/devices might be an idea... hmmm...)

...

My serial scheme is taking /way/ longer than I planned... but, I'm pretty sure a few hours will get it there. Loopback, through the graphlink, into the calc, through a small program, and back to the computer through the graphlink's other wire /does/ work... so, really, it's just a tiny bit more effort to /modify/ those bits before sending them back... and, actually, that's mostly written, but the file is now so large that it's hard to figure out what the new compilation errors mean. So, I think I need to break it up into several include files.

 My only plan for it, thus far, is to dump the contents of the Flash chip I soldered-in before I erase it and start actually working on my RAM backup program. Heh. I dunno what that chip came from, but some day I might dig its PCB out of my bin and think "man, this could actually be useful if I hadn't removed the firmware!" Though, the serial thing could also be used for dumping RAM or even ROM...

....

Next day I wound-up there again... it's not so much, or even, that I'm a hardcore thriftshopper as it is that there's a shaded parking spot, a toilet, and a place to spend sometimes a couple hours without feeling bad about not buying anything... this time... BUT when the awesome find is there... quite nice being there to find it before someone else does! Which is to say, it seems someone within the 22ish hours I was away, spotted that TI-84 Plus and thought it well worth 7 bux. I'm glad I left it for them... because I did go in thinking if it was still there, just one measly day later, I might not have the same self restraint I had the day before... I don't need it!