1 (edited by hicks 2018-01-04 20:04:21)

Topic: Acorn Electron Release 1.2.1

I've just checked in an update to the Acorn Electron core and added a new release zip 20180104_acorn_electron.zip (should appear overnight)

This version has a re-written PAL generation logic that more accurately replicates the Electron's video signal. Interrupt timing that is based on the PAL signal logic is subsequently more accurate to the point the core can be run side-by-side with an Electron and the two remain in sync (when in "authentic" mode). This version also fixes a display glitch with Firetrack caused by the video wrap logic.

As a consequence of the PAL signal changes and due to the Electron using a non-standard PAL signal, the scan line doubler alone is not able to provide a signal most monitors will display. The option for that has instead been combined with a mode selection between "authentic" and "compatible".

Authentic mode is for those who have a TV to connect to via Scart or a monitor capable of running @ 15.625kHz and putting up with the quirks in the Electron's PAL signal. Some monitors will display video when connected via HDMI but the aspect ratio will be wrong unless your monitor lets you switch to 4:3 (mine didn't) also monitors don't seem to like the odd PAL signal and have more flicker as a result than a TV would.

Compatible mode tweaks the PAL signal slightly by dropping 1/2 a scan line per field and enabling the scan line doubler. This will allow monitors to work with it over VGA/DVI and HDMI.

The downside to compatible mode is the loss of 1 scan line per frame means interrupts based on the video logic will trigger ever so slightly faster than in authentic mode and thus games will run ever so slightly faster, roughly 1 second faster than a real Electron every 5 minutes. Not really noticeable in games, but if you're running a timing/stopwatch style program keep it in mind or use authentic mode.

Re: Acorn Electron Release 1.2.1

cool i might try tomorrow after setting up refurbished a500 for vampire