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Hi! I'm wondering if the Composite/NTSC TV color artifacts, such as those on the Apple ][ or the IBM CGA, were intended by the engineers as it is or it is just a happy coincidence and/or side effect...

mov al,4
mov ah,0
int 10h ; Regular CGA 4 color mode

mov dx, 03DDh
mov al, 00010000b
out dx, al ; Bit 4 for ColorPlus special 320x200x16 color mode...

Thanks! Much better.



But how can this be done? AFAIK, the 03DDh port in the Plantronics is write only. How can the program detect that the planes has been swapped?

Good point. I just checked my program with 86Box, which emulates both machines (M24 and Compaq Portable III), and you are right: I got a big false positive.

In my detection routine I already...

Hi, Benedikt. Thank you for your input.

I tried the procedure described above on several video cards, all of them via emulation on 86Box, and it seems to work fine. The problem, as you say, is...

Thank you everyone for your ideas.

Eudimorphodon: yes! You are just right! I finally managed to distinguish a Plantronics from a regular CGA. I wrote this assembly code:



mov ax,0BC00h
...

I read the invaluable information at seasip.info. I read on this site that the Plantronics Colorplus has a register to activate the additional plane needed to use its 16 color special mode(port...

This is frankly amazing. Among other things, I never thought it was possible to do a parallax scrolling on a 8 Mhz PC using VGA hardware scroll.

Thank you very much for your inspiring work and for...

Hi! I recently past the 10 posts barrier. Yesterday, I tried to post my 11th message but it wasn't published, and I got the message that it was to be reviewed by a moderator.

Am I doing something...

Just for anyone who may be interested on VSCode, I stopped using it about one week ago. The main reason, the more and more frequent blue screens of death. That's reason enough to stop using an...

I have no problem at all with that. Back in the old days, it wasn't uncommon to develop games using a higher end system than the target platform. For example, the game studios that could afford it,...

For those who may not be aware, David Murray, The 8 Bit Guy, is making just another impressive retro programming project, this time targeting almost (or maybe every!) 8-bit Commodore computer:

-...

Hi, ibmapc. I'm glad you are learning (and I wish enjoying) learning C. As Ruud said, GCC has many differences with Borland or Microsoft C for DOS, although the basics are the same because Borland C...

Which emulator do you think gives the closest speed to the real hardware's on PC/XT machines? PCem, 86Box or Varcem?

When I try some processor intensive things, such as CGA scrolling, PCem's speed...

For my current retro programming project (a DOS game for 8088/86 or higher) I'm using these:

Operating system:
- Windows 10 on an Intel i5 laptop from 2014

Emulators:
- DosBox 0.74-3....

Very nice! It works like a charm.


if (GraphicMode != Mode_Hercules)
{
// Wait for vertical retrace
asm mov dx,3DAh
l1:
...

Thank you very much everyone for your advices!!! It's much more complex than I imagined...

You gave me a lot of good stuff to study and re-read.

Hi, Trixter. My game is been developed for...

Hi! I don't think you need to push ES as using it is usually safe, and the generated code by C don't usually needs it. You can save a few cycles and stack operations by not pushing it. You also don't...

Thank you very much for your detailed response. I forgot to say that I am programming in C language with Turbo C++ 1.0 (no OOP) and Tasm 1.01. So I tried to convert your code to C with inline...

Hi, friends! I'm happy to be here. First message.

Can you help me? I'm really getting crazy with the timing of games. I made several searches on the Internet but I couldn't find a clear step by...