Shifter Inside v1.0
I am releasing Shifter Inside, a program for the Atari ST/STe which uses classical demoscene-style top and bottom border removal techniques to extend the screen size of the standard graphical interface, GEM.
It typically enables screen sizes of 640×276 in medium resolution, or 320×276 in low resolution. No screen size improvement is available for high resolution monochrome mode.
A STE-only version also expands the horizontal size by a few pixels, achieving 672×276 pixels in medium resolution and 336×276 pixels in low resolution.
Shifter Inside does what is technically possible to use border removal on the system shell. However, such techniques usually require to work on no interrupt environments, which is not possible when running the user OS. Even though countermeasures can be used to avoid being disturbed by the system clock or keyboard interrupts, there is no known way to counteract disturbances from DMA transfers (Floppy, Blitter, ACSI devices) which basically stop the CPU during transfers.
This project is Free/Open source software. It is released under the terms of the GPLv3 license. The source code is available on the Codeberg repository.
I hope some people will find it useful!