39-year-old Radio Shack laptop gets a new processor and retains the original screen
39-year-old Radio Shack laptop gets a new processor and retains the original screen
The 100 model featured a 2.4 MHz Intel 80C85 processor, 8 to 32 KB of RAM, and an 8-line, 40-character monochrome LCD display with no backlight. It doesn't look like much compared to today's portable beasts, but journalists loved the Model 100 because they could comfortably write stories on the go using its built-in text editor. It also included Microsoft BASIC, a terminal program, and an address book in ROM.
Enlarge / Excerpt from a 1983 Radio Shack computer catalog page featuring the TRS-80 Model 100 portable computer.
Radio Shack / VC&G
While some people are updating the 100 model using new LCDs and processors (keeping only the case and keypad), Cass decided to attempt an interface with the vintage 240 display × 64 pixels of the notebook. He found this particularly difficult because the computer handles controlling the screen in an unconventional way compared to today's LCD panels.
"The M100's LCD is actually 10 separate screens, each controlled by its own HD44102 driver chip," writes Cass. "The driver chips are each responsible for a 50 by 32 pixel region of the screen, except for two chips on the right side which only control 40 by 32 pixels." Its designers chose this method, Cass explains, because it speeds up text display with limited available memory.
Okay, here's my demo: first it fills and clears the screen by writing to all the chips at once, then loads a full screen bitmap as fast as the display can go, then use software bank switching and partial refresh for fast scrolling! pic.twitter.com/VbF2vgaG9L
— stephencass (@stephencass) September 21, 2022
After developing the protocol for the display, Cass built an interface between the display and a modern Arduino Mega 2560 microcontroller. As the project...
The 100 model featured a 2.4 MHz Intel 80C85 processor, 8 to 32 KB of RAM, and an 8-line, 40-character monochrome LCD display with no backlight. It doesn't look like much compared to today's portable beasts, but journalists loved the Model 100 because they could comfortably write stories on the go using its built-in text editor. It also included Microsoft BASIC, a terminal program, and an address book in ROM.
Enlarge / Excerpt from a 1983 Radio Shack computer catalog page featuring the TRS-80 Model 100 portable computer.
Radio Shack / VC&G
While some people are updating the 100 model using new LCDs and processors (keeping only the case and keypad), Cass decided to attempt an interface with the vintage 240 display × 64 pixels of the notebook. He found this particularly difficult because the computer handles controlling the screen in an unconventional way compared to today's LCD panels.
"The M100's LCD is actually 10 separate screens, each controlled by its own HD44102 driver chip," writes Cass. "The driver chips are each responsible for a 50 by 32 pixel region of the screen, except for two chips on the right side which only control 40 by 32 pixels." Its designers chose this method, Cass explains, because it speeds up text display with limited available memory.
Okay, here's my demo: first it fills and clears the screen by writing to all the chips at once, then loads a full screen bitmap as fast as the display can go, then use software bank switching and partial refresh for fast scrolling! pic.twitter.com/VbF2vgaG9L
— stephencass (@stephencass) September 21, 2022
After developing the protocol for the display, Cass built an interface between the display and a modern Arduino Mega 2560 microcontroller. As the project...
Enlarge / Excerpt from a 1983 Radio Shack computer catalog page featuring the TRS-80 Model 100 portable computer.
Radio Shack / VC&G
