This dumb CMOS chip is pretty much not formally supported by any FOSS programmer out there, as they all support the 73F instead!
Good news though, is the 72F and 73F are functionally the same (apparently), so using something like ‘AsProgrammer’ or ‘NeoProgrammer’, and just editing their chiplist file (lives in the root folder of the programmer.exe) and just replace ’73F’ with ’72F’.
Another gotcha about this chip is that you CANNOT USE A CLIP TO PROGRAM IT WHILST IT IS SOLDERED TO THE DEVICE. You need to yoink the chip off the PCB and use the little springloaded holder thingy. This is due to a few possible reasons (I don’t know for sure, I’m no scientist):
1. The clip is shit. The pins don’t make firm enough contact with the CMOS legs and it doesn’t work.
2. The clip’s cable length is too long and unshielded, so the signal strength is too crappy to work. When I used the clip and tried to auto-detect the chip, it’d give me a new SDI ID every time.
3. Circuitry on the board may be messing it up somehow. I dunno how, but people far smarter than me over at badcaps.com seemed to suggest you can’t reprogram the chip in-situ due to other stuff on the board. IDK.
What caused me to find all this out? My Lenovo Thinkpad L14 Gen 1 (An absolute beast of a laptop from 2019, with 8 cores, 16 threads, 1TB NVME and 64GB of RAM) decided to stop turning on. So I suspected the BIOS to be cooked, and rather than just buy a pre-programmed BIOS chip and swap it, I decided to fix it myself by buying the programmer and all sorts, but I’m glad I did, because now I can use this thing to re-program a heap of other stuff, like my Xiaomi ‘Mi Home’ PTZ cameras to a jailbroken firmware that allows them to be used as ONVIF cameras with RTSP streaming, and absolutely no exporting my entire life in Full HD 25 FPS directly to Chinese servers, that I need to pay for the privilege to see for myself.
How did I unsolder the chip? Good question. My honest answer is that I used a cheap (but frankly extremely effective) Ozito PXC cordless 18v hot air gun, bought from Hammer Barn (Bunnings) for an absolute steal. This HAG (hot air gun) has a far better spec sheet than the Ryobi and even Makita variants, and the batteries are absolutely dirt cheap. Ditch the 300w Ms. Piggy 240v HAG and pick one of the Ozito boys. (For you yanks, or Yank adjacents, the Bauer ’20v’ cordless hot air gun is EXACTLY THE SAME!. For the Europeans, Ozito = Einhell). But I digress…
I used the hot air gun and blew around the mainboard area from ~15cm away, in a brush stroke motion up and down the length of the board, whilst the HAG heated up. I did this because there’s a lot of copper in that mainboard, and it’ll do it’s best to sink out all of the heat you’re going to be putting into the CMOS chip, as to pre-heat the board will help prevent you from baking the chip because it wouldn’t let off the solder. I then focused the heat onto the chip’s legs, alternating every second, at a distance of 1-2cm (half-one inch for you Yanks), using some angled metal tweezers, grabbing onto the chip, and applying some light upwards pressure. Within a few seconds, the chip ‘plucked’ off the board. I initially thought I’d ripped the pads off, but no, the legs loosened up just enough to come off the solder.
I then whacked the chip into the holder, USING THE 1.8V CONVERTER BOARD, plugged into the CH341A, plugged into my other L14 Thinkpad, using AsProgrammer with the modified chiplist described above, and it instantly came up. ezpz.