Text corruption after BIOS on internal LCD only, external display fine on Portable PC III (Orchid)

[Jason Novak]

I have a Portable PC III by Orchid Systems - a 386 compaq portable III clone that takes a regular MB with a special video card for the LCD.

Plugging in a VGA monitor, everything works fine - the initial BIOS boot screen, and then DOS afterwards. Using the internal LCD screen instead, the BIOS boot screen is fine, however as soon as it goes past that to the summary / DOS all the characters are scrambled. Being that this is a custom part, I can't really swap it out.

I tried pulling cards, moving cards, clearing CMOS, changed the video card DIP switches, but nothing works. I saw a thread about one of these cards with bad VRAM, however that fact that the BIOS screen and menus are fine, not sure if this is the case? What else could be different after the boot screen that would cause an issue? Refresh rate?

I ran Checkit on the external monitor and it passed all tests, including video ram.

index - powered by h5ai v0.29.0 (https://larsjung.de/h5ai/)

index - powered by h5ai v0.29.0 (https://larsjung.de/h5ai/)

retro.timb.us

 

[Plasma]

It looks like some kind of character font problem. The BIOS screen is using an 8x19 font. The boot screen is expecting an 8x19 font but using an 8x16. So the character data is shifted.

Not sure how to fix it, but if you have the mxw utility, you can try setting 80x60 mode as a workaround.

 

[Jason Novak]

Thanks, it does seem to be font related. Using the factory utilities that let me switch between the external display and the internal via keystroke and a config tool, I notice turning off "extended" mode seems to switch from NTSC to CRT, which I assume changes the font, and it works, at least until I power off so a bit clunky. I don't see a way to set the font in the utility. Also switching to any other mode, ie CGA/ EGA instead of VGA and the internal display works fine too.

I tried fix8x14b, which says my system supports both 8x14 and 8x16 fonts, and when it does the 8x14 test the internal display does work correctly within that test before going back to bad font

I guess I need a utility that I can just stick in my autoexec.bat to switch the font, any suggestions - I'm not sure what the mxw utility is? The weird thing is I see this issue even without any drives connected, so no OS that maybe doing something with the font, it still happens. It's weird that out of the box they'd make a PC with an internal VGA LCD screen that isn't compatible with DOS by default with the bundled special video card.

 

[Plasma]

I think "expand" mode is supposed to stretch the characters to 8x19 to fill up the 480 scanlines. So if you turn it off, the characters are 8x16 and only using 400 lines.

The mxw utility is in the VGA display adapter pdf that you linked. But I don't know if it can disable expand.

Still not sure about the root cause for expand mode not working after boot. Could be a hardware problem or maybe a BIOS bug.

 

[Jason Novak]

Thanks, yeah I remember that now - it does seem like it's exactly what I need, it wasn't including in the driver packages I'd come across on the web and I didn't have anything else that originally came with it, disks or HDD, I'll do some more searching. Hopefully it's not something custom for the PC III

 

[Jason Novak]

Here's where I've settled at for now for anyone else having the same issue at least letting it switch into a usable mode automatically.

I tried vmode.exe which lets you set the VGA mode, ie 10 or 11, though when I start something like edit the mode is switched

WPDOS - Text Mode Survival Guide

clgd641x
This driver has a newer version of switcher.com than the GD610/620 drivers with hardware extended more that scales better.

VOGONS Vintage Driver Library

I run it from my autoexec.bat, and you can either just hit ctrl-shift-H (or E) or automate it with scancode to stuff in the shortcut automatically from autoexec.bat from here:

Bret Johnson's Home Page

scancode.com M3 CTRL-SHIFT-H

One issue with this though is while using something like edit still works, a few special characters, like the grid characters in the scroll bars, are garbled.

Hopefully someone finds the official pc III text mode app at some point