The Sinclair QL Forum

Is it a known bug that ptr_gen does not work correctly on JSU rom if the computer is started in (F2) TV mode ? My boot program switch to mode 4 before loading ptr_gen, but as soon as it gets loaded, the basic windows display becomes corrupted.

However, on the same computer with the same JSU rom, if I choose F1 (monitor) at startup, the problem does not occurs. With a minerva rom, everything is fine even if I boot with F2.

ptr_gen version: 2.05
tk2 version: 2.23

François

JSU ROM QLs actually have a different (lower) resolution in NTSC TV mode, and the y screen space is limited to 192 instead of 256 pixels in this mode (See QL Technical Guide:

For TV operation, a 60Hz 524-line non-interlaced system is used in which the number of raster lines available is limited to 192. In order to ease the task of software conversion, an alternate display font is provided which allows a 6x8 character square instead of the usual 6x10. This ensures approximately the same number of visible rows of text on both PAL and NTSC QL s, at the cost of true descenders and reduced vertical spacing. The default windows and graphics scaling for TV operation are different from those of the English QL .

Supporting this mode would have meant to have a special version of the Pointer Interface, and I find it unlikely that the Pointer Environment would support it - At least I've never heard of such a version. So, not really a bug, but a non-supported version of the hardware.

QDOS obviously has been adapted to this mode, trying to emulate the "normal" QL's scaled coordinate system as well as possible. As the Pointer Interface works in unscaled pixel coordinates, this obviously does not help.

tofro wrote: ↑Tue Nov 08, 2022 7:22 pm JSU ROM QLs actually have a different (lower) resolution in NTSC TV mode, and the y screen space is limited to 192 instead of 256 pixels in this mode (See QL Technical Guide:

Supporting this mode would have meant to have a special version of the Pointer Interface, and I find it unlikely that the Pointer Environment would support it - At least I've never heard of such a version. So, not really a bug, but a non-supported version of the hardware.

Thanks for reminding me about the 192 lines vs 256. But, since start of screen in the same and number of bytes per lines is the same, it is just a smaller screen but otherwise should behave the same. If the managed windows are displayed on the top 192 lines of the screen, the same « program logic » should work.

I agree with you, the JSU TV mode is simply not supported. However it is surprising that it does not works ‘as is’ as the screen layout in memory is the same and, even if the 64 lower lines are not displayed, the memory for them is there… I am wondering what part of the code starts going awry because of the 192 displayed lines. Intriguing.

François

Has anyone ever heard or read that the PE doesn't run on JSU Roms? (up until now)?

FrancoisLanciault wrote: ↑Tue Nov 08, 2022 6:17 pmptr_gen version: 2.05
tk2 version: 2.23

No idea, but apparently I made a version 2.06 which "Fixed mode changing/crashes on QDOS", so you might try to check that one out first.

mk79 wrote: ↑Wed Nov 09, 2022 11:28 am

FrancoisLanciault wrote: ↑Tue Nov 08, 2022 6:17 pmptr_gen version: 2.05
tk2 version: 2.23

No idea, but apparently I made a version 2.06 which "Fixed mode changing/crashes on QDOS", so you might try to check that one out first.

Took some time, but I finally check ptr_gen 2.06 on my JSU ql and the problem is still there.

Will try to check early versions to see if they work.

François

Just try an old disk from QRam or similar. If such an original disk does not work, there may be problems elsewhere.