big display of uqlx on rPi

Discussion and advice about emulating the QL on other machines.
Brittle Membrane
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Joined: Mon Mar 07, 2011 11:43 am

big display of uqlx on rPi

Postby polka » Sun Feb 05, 2017 7:11 pm

Hi all !

As I am playing already for some rather long time with the Raspberry Pi (together with my QL and other emulators), I was curious to try to install Uqlx on it.

It worked almost without trouble, but I was disappointed with the size of the screen/characters.

But I found "my simple way" to better that : use of the xzoom command from a terminal window with following parameters :

xzoom -mag 2 3

dispays a nice 512x256 (basic) QL screen with the same (default) aspect ratio as my (original) 4x3 monitor.

So circles are circles, squares are squares, etc. and the characters are legible.

But I am still a little dissatisfied : the speed of the emulation cannot be adjusted (to the speed of the original QL), it is a lot faster (even on my 1st generation Raspberry Pi), and this is somehow problematic in two ways :

1/ The refreshing rate of the xzoom program cannot follow some animated displays.

2/ for some unknown reason, the screen editor of my Computer One Forth does not work properly : I already noticed that when using Qemulator at full speed on my PC (whereas it worked OK when Qemulator was let running at "the speed of an original QL" or even at "the speed of the Gold Card")

Here a screen shot of the result :

A/ the emulation (this window must be active for the keyboard and the mouse)

B/ the console on which I passed the command xzoom

C/ the zoomed image (width x 2 : heigth x 3)

screen shot

Bye Paul

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Re: big display of uqlx on rPi

Postby tofro » Sun Feb 05, 2017 11:18 pm


assuming you have an HDMI display, changing the RPi's own screen resolution is probably much easier.

Your SD card should have a file "config.txt" in its root directory.

If you insert two lines saying

Code: Select all


The RPi will start up with a screen resolution of 640x480 on the HDMI display. Displaying uqlx that way (obviously, now you can no longer use resolutions higher than this size), will give you a close to the original screen display.

With a little fiddling, you might even be able to set the RPi native resolution to 512x256 and maybe even a proper aspect ratio.

This site ...
gives more info on this.


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Super Gold Card
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Re: big display of uqlx on rPi

Postby XorA » Mon Feb 06, 2017 9:39 am

If you want BBQL games on Pi look into the mame ql emulation. It runs at bbql speed and has nice scaling.


Brittle Membrane
Posts: 100
Joined: Mon Mar 07, 2011 11:43 am

Re: big display of uqlx on rPi

Postby polka » Mon Feb 06, 2017 12:52 pm

hi Tobias,

Concerning legibility and aspect ratio, I am satified with my solution (xzoom -mag 2 3), and I want not change the rPi resolution, because I prefer the big QL display to happen in a xwindow and be able to open other windows for rPi programs.

My other problem is the control of the speed of the emulated QL. Not so much because of the refresh rate of the xzoom app. More because of the malfunction of Computer One page editor.

So, I intend to reverse ingeneer it or to rewrite it. A thrilling challenge for my sagacity !

A simpler way would also be to add to Computer One Forth the ability to compile plain text files (like SuperForth). I will do this first !

May the Forth be with us ! Paul

Anyway, I consider this QL emulation on rPi just as a curiosity, I am fully satisfied with Daniele's Qemulator on my PC. And I am not thrilled with emulations other than "plain ooooold QLs", original 512x256 displays, limited memory and speed.

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