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Pseudonymous maker “Sunshine701c,” hereafter merely “Sunshine,” has designed a Teensy-powered adapter which helps you to join the keyboard of a classic Hewlett-Packard 200LX palmtop to a contemporary PC as a USB machine — as a part of a venture to upcycle a deceased instance of the machine.
“I am engaged on a venture in the intervening time, principally sticking a Raspberry Pi into the case of an outdated [HP] 200LX palmtop pc that broke on me,” Sunshine explains. “The beginning of this venture is to adapt the outdated keyboard in order that it may be used as a regular USB keyboard. I used an outdated Teensy 2.0 microcontroller and kbfirmware.com (very outdated I do know) to [do] this, together with a customized interposer PCB to adapt the very bizarre pad spacing on the keyboard connector to the Teensy.”
A cautious tracing of a classic palmtop’s keyboard circuit delivers an adapter for a USB controller. (📷: Sunshine701c)
Launched in 1994, the HP 200LX was a palmtop PC constructed round an Intel 80186-compatible processor operating at 7.91MHz and supporting as much as 4MB of RAM with storage growth accessible by way of a PCMCIA slot in conjunction with the machine. The bottom-performance present Raspberry Pi mannequin, in the meantime, is the unique Raspberry Pi Zero, which boasts a 1GHz CPU and 512MB of RAM.
Inserting a Raspberry Pi into an HP 200LX, then, can be one thing of an improve — although Sunshine was a request. “I urge, PLEASE DON’T tear aside a wonderfully working 200LX for a venture like this,” the maker writes. “I tore mine aside as a result of the LCD and [motherboard] had been each busted. Until you are in the identical boat, with a damaged keyboard AND LCD, think about using a unique small type issue keyboard, it’s going to in all probability be simpler to implement and use, I am solely utilizing this one to utilize outdated expertise that may in any other case be thrown out.”
The maker has launched the board design and supply code for others to make use of in the event that they too have a deceased 200LX at hand. (📷: Sunshine701c)
To get the keyboard speaking to present programs, Sunshine needed to probe every hint on the versatile circuit to determine which key corresponded to which pin on the weird connector. With that map in thoughts, the maker constructed an interposer board which sits between the keyboard connector and a Teensy 2.0 microcontroller board — which, in flip, listens for key presses and sends them over USB to a contemporary host machine.
Extra info on the venture is obtainable on Sunshine’s Reddit publish, whereas supply code and KiCad venture information have been revealed on GitHub beneath the reciprocal GNU Normal Public License 3.
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