Stephen was faced with a broken Radio Shack laptop. He replaced the logic board with a modern one so he could use the vintage screen. Last week, he wrote about his adventures for Spectrum.
The Radio Shack TRS-80 Model 100 is one of the first laptops ever produced and features a one-piece "slate" form. Its claim to fame was that it had a great keyboard and was able to run for up to 20 hours on four AA batteries.
The Model 100 had an Intel 80C 85 processor, 8 to 32K of RAM, and an eight-line, 40-character display. Journalists loved the Model 100 because they could comfortably write stories on the go using its built-in text editor, even though it doesn't sound like much compared to today's portable beasts. It included a terminal program and an address book.
Advertisement
While some people upgrade Model 100s with new screens and computers, Cass decided to try and use a vintage display. It was challenging because the computer handles driving the display in an unconventional way.
The M 100 has 10 different displays, each controlled by its own driver chip. The driver chips are responsible for a 50-by-32-pixel region of the screen except for two chips at the right-hand side. The designers chose this method because of its speed.
Okay, here’s my demo: first it fills and clears the screen by writing to all chips at once, then loads a full screen bitmap as fast as the display can go, then uses hadware bank switching and partial refresh to fast scroll! pic.twitter.com/VbF2vgaG9L
— stephencass (@stephencass) September 21, 2022
After working on the protocol for the screen, he built an interface between the screen and a modern microcontroller. He can display bitmapped graphics on the Model 100's display screen. He wants to use a Teensy 4.1 development board to interface the screen and keyboard, which would make for a powerful portable machine with a vintage feel.
You can find more information about his project on the website. Stephen, good luck.
All Rights Reserved © 2024
