The Sinclair QL Forum

I have recently got a new computer with Windows 10 on it. And I have noticed an odd behaviour with it and QPC2.

I don't know if it's an issue with QPC2 or not, could someone try to replicate the problem.

If I start QPC2, then switch to another Windows task (burying the QPC2 window). Then not touching anything, wait for the screen saver to come on, Wait a little longer, then start moving the mouse/switching between tasks. Then a "QPC QL emulator for win 32 has stopped working" error appears.

It seems to be tied into the Screen saver. As I have now switched off the Screen saver, and I have not seen QPC2 crash (yet).

No problem here. QPC2 is working even after switching on after suspend mode without any problems.

The only problem with QPC2 is, that a lot of old programs (especially games) are not compatible with it, but this is also true with uQLx (at least with Minerva).

ql_freak wrote:No problem here. QPC2 is working even after switching on after suspend mode without any problems.

The only problem with QPC2 is, that a lot of old programs (especially games) are not compatible with it, but this is also true with uQLx (at least with Minerva).

Many of the problems with such games arise from either writing direct to screen or assumptions about system variables addresses, assumptions about calling fixed ROM entry points, etc.

Many such "difficult" games will work on QPC2 if started in a 512x256 QL mode 4 or mode 8 screen (that starts QPC2 as close to an original QL as it gets). Sadly, it doesn't always work as well if you start QPC2 in a high resolution or high colour mode and later switch modes back to standard QL screen.

Additionally, many games will work if you use the QPC_QLSCREMU command. QPC2 can maintain a "32K QL screen" (512x256 QL colours) at an address equivalent to that of a standard QL screen, and shadow copy that video screen to the visible video screen, even able to do a limited colour conversion.

There will always be a few games written in such a way that they will only work on a standard QL or even only on a single ROM version due to assumptions made about machine configuration, or position dependent machine code (such programs may even be described as not fully QL-compatible, even!)

Over the years, I came across one or two games which would work fine from microdrive on a 128K QL then fail as soon as you added a disk drive, simply because the small amount of memory used by the disk system meant enough changed that such games no longer worked!

In theory, it might be possible to add a small loader to such programs to calculate the differences between where the game was meant to run from and where the current machine configuration would make it run from and try to hack any absolute addresses in the code to adjust it to give a better chance of running. Not a job for the faint hearted, I'm not even confident such a loader would stand a great chance of working to be honest.

Best known non-working candidates are The Pawn and Computer Scrabble. The first loads an own OS fully by-passing QDOS, the second has a very special way to read the keyboard.