The Tecra 530CDT uses the C&T 6555x VGA controller, which fortunately has a DOS scaling utility to alter how the screen scales non-native video modes - the 530CDT has a 1024x768 panel, and any non-native resolution will be scaled by some mechanism to 'best' fit the screen.

The Toshiba BIOS has an option to enable/disable scaling (but that's literally all it does: on/off). Fortunately those C&T chips can use VEXP (https://archive.org/details/vexp13) to customise the scaling.

It's not great, but it *is* a hell of a lot better than most laptops of the same age which had precisely zero scaling options. The same panel and VGA controller is in my 480CDT and the VEXP tool can get some of those modes looking a little better.

Here's my 480CDT screen, with scaling on vs off:

Are you now able to enter the BIOS on this machine? I remember in your original thread you had issues accessing it. There is a simple on/off option in the BIOS, but using VEXP once DOS has booted will give you a few more options (mainly affecting text-mode type screens, such as the ones shown above).

Unfortunately, proper non-linear scaling only really took off in laptops with the ATI Rage LT Pro, Geforce Go, S3 Savage and above. Before the time of those chips you either had simple power of 2 scaling (so unless you had a panel that was some multiple of all your possible screen modes - which is impossible to achieve - you would always have some modes with black borders), basic horizontal bilinear scaling (on a few VGA chips - meaning the X resolution scales okay, but the Y resolution can look blocky) or nothing at all.

On early laptops, the C&T chip is probably one of the best in terms of scaling options; similar age Neomagic, Trident, S3 have **no** options to tweak the scaling. It's usually (depending on manufacturer) either a BIOS setting or a Function+hotkey combo to enable/disable... but that's it.

megatron-uk wrote on 2025-03-08, 17:44:

Here's my 480CDT screen, with scaling on vs off: […]
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Here's my 480CDT screen, with scaling on vs off:

The attachment 480cdt_scaling.jpg is no longer available

Are you now able to enter the BIOS on this machine? I remember in your original thread you had issues accessing it. There is a simple on/off option in the BIOS, but using VEXP once DOS has booted will give you a few more options (mainly affecting text-mode type screens, such as the ones shown above).

Unfortunately, proper non-linear scaling only really took off in laptops with the ATI Rage LT Pro, Geforce Go, S3 Savage and above. Before the time of those chips you either had simple power of 2 scaling (so unless you had a panel that was some multiple of all your possible screen modes - which is impossible to achieve - you would always have some modes with black borders), basic horizontal bilinear scaling (on a few VGA chips - meaning the X resolution scales okay, but the Y resolution can look blocky) or nothing at all.

On early laptops, the C&T chip is probably one of the best in terms of scaling options; similar age Neomagic, Trident, S3 have **no** options to tweak the scaling. It's usually (depending on manufacturer) either a BIOS setting or a Function+hotkey combo to enable/disable... but that's it.

"Are you now able to enter the BIOS on this machine?" Yes, it is now very easy because I just have to execute TSETUP.EXE from Freedos. Before removing the password it didn't work but now it's ok (reflashing the bios may also made it working) I'm not sure if the option on bios I was talking about is same thing as full screen or not, it stretches up and bottom but it's dirty, ok for AT2 (but original display of AT2 is better in my opinion) but garbage for ST3 and IT2 because of the font.

Thank you for vexp13 ! I will test it tomorrow it will probably help a lot

ST3/IT2 are 80x50 text modes so there's probably going to be some intense gaps and aliasing when Toshiba's pulling it out.

Vexp13 worked perfectly with VEXP M2 T as suggested in txt. Thank you @Megatron-uk !

It is a little strange with AT2 to see it stretched on top and bottom (because I'm not use to it) but it use all the screen and there is no problems with font so it's completely ok, the lines are just a little far away from each other, not a big deal at all. And on IT2 and ST3 it's perfect

Maz Hoot wrote on 2025-03-09, 11:35:

Vexp13 worked perfectly with VEXP M2 T as suggested in txt. Thank you @Megatron-uk !

It is a little strange with AT2 to see it stretched on top and bottom (because I'm not use to it) but it use all the screen and there is no problems with font so it's completely ok, the lines are just a little far away from each other, not a big deal at all. And on IT2 and ST3 it's perfect

Good stuff!

The scaling issues are one of the reason I've been hunting for ATI based DOS laptops, as they were one of the earliest to introduce a nice full-screen scaling option for *every* video mode. ATI options aside, the C&T is probably one of the better options for DOS gaming on a laptop precisely because it has more than just on/off scaling options.