Here is the new release of zeST, mostly with fixes to make life better. Scan doubler rework The scan doubler has received particular attention for this new release. Indeed, a large part of its logic has been rewritten. This module is one of the first implemented in zeST, even before I got the TOS system to boot. It was already there when I displayed my first image out of the Atari ST logic on a HDMI screen.

This latest release fixes an important bug that made the system hang in specific memory access conditions. Specifically, on the Z7-Lite board, just changing the floppy disk image and then resetting the system triggered the bug. I didn’t see it because most of the development and debugging was done using my Z-Turn board. This bug was introduced in last September’s release, with the new memory interface that featured an internal cache.

New user interface A complete rework on the user interface has been performed, and this results in a totally new, user-friendly UI. The old MS-DOS-style “text mode buttons” design has been replaced with a list view system, in which you can navigate all the entries and settings using the arrow keys. Joystick support will be added in a future release. Instead of the mono-space Atari system font, the interface is now using a clean, proportional bitmap font.

A new release of zeST is available! On the menu: support for a new board, improved floppy management, and bug fix. New board support zeST now fully supports the TE0726 “ZynqBerry” board from Trenz Electronic. This is a Raspberry Pi 3-shaped board that features the same interfaces as the Pi, including 4 USB ports and an audio output jack connector. Porting zeST to this board was rather challenging because I had to deal with various issues that I never encountered on other boards before:

A new release of zeST is available! The following is a comprehensive description of the changes. More demos working A number of fixes have been made, improving compatibility with some demos that didn’t load into zeST initially. They mainly improve the loading of floppy disk images on some demos that use their own low-level code to address the Atari ST’s floppy disk controller and DMA system. As you can see from the dedicated GitHub issue page, all demos I had previously identified as not able to load are now working.

This new zeST release brings a major fix in memory management, introduces “shifter wakestates” , properly implements MMU configuration, and includes other small fixes. Memory management zeST now includes a much better manager for accessing the main DDR memory of the Zynq board it’s running on. This is not strictly related to the Atari ST implementation, but rater to the management of the host hardware to be able to use it with the best performance.

The new zeST release mostly brings under-the-hood fixes, but with important stability and compatibility improvements. Support for larger ROMs There used to be “bi-TOS” hardware mods, mostly on Mega ST computers. Those mods allowed the user to switch between two possible operating system versions: the latest, improved TOS 2.06 that you can find on the Mega STE, and the original TOS 1.04 for compatibility. Those two versions were installed on different ROM chips that could be selected using a hardware switch.

With the latest release of zeST, some of the latest, trickiest video demo effects are now working. This includes the syncscroll and fullscreen from the Closure demo by Sync, that you are now able to fully enjoy on zeST! The other technical demo by Sync (what.if.game), which features a novel Shifter freezing technique to enable 4-pixel scrolling, is also working. Some bugs in the latest GLUE chip rewrite have also been fixed.

This new releases has several improvements. Better joystick support Important code reorganisation has been done, so that USB controllers and joysticks are detected in a more predictable way. Different joysticks are now assigned to the ST joysticks in detection order. This means the two joysticks will remain in the same order from one time to the other. Some peripherals will not be incorrectly detected as joysticks anymore, and a basic detection heuristic is used to identify how peripherals reports their events, as this may differ between devices.

The new 2024-02-11 release is available. On the menu: monochrome mode, RAM expansion, and keyboard bug fix. Monochrome mode zeST was having display issues when running in monochrome high resolution mode. There was an unwanted white border on the left side of the screen, some pixels were not displayed properly and the scanlines were larger than the expected 640 pixels of width. This is fixed now. In parallel, I have been conducting experiments on enabling a monochrome mode that would be more compatible than the standard one of some monitors, especially because of the non-standard 71.