ever read the term "glue logic"? here you have it literally! note this is not used, and was removed. but it works. it is a digital MOSFET, BS303, and it is used to negate a signal bit. you need additional resistor for that...hence it is called "RTL" (resistor transistor logic). it is out of use for decades, but can make sense very well for a single bit, if you just need one bit! normally you would required additional IC, or alternatively, single-gate logic. but these chips are not always available, if it is just for the reason you do not always maintain a stockpile of these logic ICs. i am using oldfashion shift registers together with PIC. they write that PIC technology is up to replace this logic, especially glue logic. but i figured out they can work together. well in many cases you just take one of these new technology ICs with a large count of pins. but sometimes you do not want to maintain this advanced technology- for various reasons. for instance, if you use the 16F54, you only need to worry about 512 program words, and the instruction set is very limited. can you imagine what to do with 25 bytes of RAM? i have first used shift register as hardwired "startup sequencer", after reading "CMOS cookbook" (a title from the 1970s). such shift register can do many things... but nowadays you would use a microcontroller for startup of electronics board, and not hardwired shift registers! but since then, i enjoy to use these registers. they are available as little as 30 to 50 cents, old stock (NOS) from the 1980s, and also new production. it is a little bit like using punched card computers...even nowadays. because the means, interfaces, to "hack", "phreak", or "geek up" such technology are very limited, if not absent. well the truth is they are now going to print small circuits on paper, and plastic foils, using electronic ink... also this technology has limits for speed and complexity, so here you have an equivalent- old fashion RTL logic. well back then there have been no MOSFETs available- for the price of cents. to see the complete PCB, look for "4BITS COMMAND CENTRE" a few pictures earlier...

The Loctite Super Glue Gel stands ready to be deployed. This Gel Control is supposed to help avoid those annoying super glue disasters where the glue goes everywhere but the place you wanted it. I certainly didn't want that happening to my Macbook! Note: Glue wasn't needed in the end. Apple are replacing top covers even out of warranty due to a design flaw.