Confronted with a damaged Radio Shack pc from 1983, IEEE Spectrum editor Stephen Cass did not throw it away. As a substitute, he pulled out the good judgment board and changed it with a contemporary microcontroller so he may regulate the antique display screen. Cass wrote about his journey intimately for Spectrum ultimate week.
Cass carried out his operation on a Radio Shack TRS-80 Type 100—probably the most first laptops ever produced—which includes a one-piece “slate” shape designed by way of Kyocera and launched because the NEC PC-8201 in Japan. Its declare to popularity was once now not most effective its small transportable dimension (at 2 inches thick and three.9 lbs), however having an excellent keyboard paired with its talent to run for as much as 20 hours on 4 AA batteries.
The Type 100 incorporated a 2.4 MHz Intel 80C85 CPU, 8 to 32K of RAM, and an eight-line, 40-character monochrome LCD and not using a backlight. It does not sound like a lot in comparison to lately’s transportable beasts, however reporters beloved the Type 100 as a result of they might very easily write tales at the move the use of its integrated textual content editor. It additionally incorporated Microsoft BASIC, a terminal program, and an deal with e-book in ROM.
Whilst some other people improve Type 100s the use of new LCD displays and CPUs (preserving most effective the case and keyboard), Cass determined to try an interface with the transportable’s antique 240×64 pixel show. He discovered it in particular difficult for the reason that laptop handles riding the show in an unconventional means in comparison to lately’s LCD panels.
“The M100’s LCD is truly 10 separate presentations, each and every managed by way of its personal HD44102 motive force chip,” Cass writes. “The motive force chips are each and every liable for a 50-by-32-pixel area of the display screen, with the exception of for 2 chips on the right-hand facet that regulate most effective 40 by way of 32 pixels.” Its designers selected this technique, Cass says, as it accelerates textual content show with restricted to be had reminiscence.
K, right here’s my demo: first it fills and clears the display screen by way of writing to all chips immediately, then so much a complete display screen bitmap as speedy because the show can move, then makes use of hadware financial institution switching and partial refresh to speedy scroll! %.twitter.com/VbF2vgaG9L
— stephencass (@stephencass) September 21, 2022
After understanding the protocol for the display screen, Cass constructed an interface between the display screen and a contemporary Arduino Mega 2560 microcontroller. Because the venture stands now, he can show and scroll bitmapped graphics onto the Type 100’s LCD. His subsequent step can be to check out to interface the display screen and keyboard (with a Teensy 4.1 construction board to deal with keyboard communications) to a Raspberry Pi 4 compute module, which might make for a formidable transportable device with a antique really feel.
You’ll be able to learn extra concerning the technical main points of his venture on IEEE Spectrum’s site. Just right good fortune, Stephen!