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 71.2 Hz vertical refresh frequency. It appears that the monitor I use and that was not able to display the original 71.2 Hz screen mode was not able to display the experimental 60 Hz mode I made as an experiment. The problem is that there is no standard (VGA? VESA?) screen mode to display such resolutions with the ST’s fixed 32 MHz pixel clock.

So for now, compatibility for high resolution has been set aside, and will be worked on again when a proper 1080p upscaler is released in the future.

RAM expansion

You can now use 14 megabytes of RAM in zeST.

See the settings in the getting started page.

Keyboard bug fix

The latest release(s) of zeST had a troubling issue with keyboard management. From my investigations, it seemed that the serial communication between the IKBD (the keyboard processor) and the keyboard ACIA was lost. Problem, when I was trying to enable my debugging setup in Vivado (involving the deactivation of hierarchy flattening), the problem disappeared !

So actually, by changing the default build settings to some closer to my debug setup, the problem is more like being worked around than fixed. However, if it ever reappears, the new setup will make debugging easier.

That’s all folks!

Thank you for reading this release report.

As usual, download and installation instructions are available on the getting started page.