Tandy 1000 TL - 85 Color Demo

[reenigne]

I had a random thought of trying to optimize two screens, one 80x25x16 text and one 320x200x4 graphics and try to figure out the best set of common data closest to the target image

And flip between them? I don't think you can do that without the screen rolling (on a real monitor)...

Yeah, the problem there is that you're switching the CRTC between two possible input clocks (1.79MHz for 80-column text mode and 895KHz for other modes), so you'd need cycle-exact timing to make sure the clock gets switched over exactly at the beginning of the frame. It can be done, but only if you limit your code to 4.77MHz machines. 40-column text mode could be done though, and if you use 2 scanlines per character row, then each 8-pixel by 2-scanline block will be using the same video RAM addresses no matter what the mode is, which will probably simplify things. You can also choose between two pages in text mode, so you get to choose whether your text mode screen shares its data with the odd or the even scanlines of the graphics mode screen.

I look forward to that as well!

Me too!

 

[deathshadow]

All Tandy 1000 models have RAM for up to four 320x200x16 pages.

How exactly would that work given there's only B8000-BFFFF -- 32k actually mapped to video memory, there's no paging to make the video display using RAM outside B8000 to BFFFF, and 320x200 in 16 colors is just a hair under 32k?

160x200 you can get a whole whopping two pages.... Four pages at 320x200x16? I don't think so Tim. That's 128k -- where would you map it? It's not like there are bank swapping controls. (or a reliable way to even have a bank to swap FROM)

There's a reason the TL/SL only has ONE page of 640x200x16, and that's because they map it from B0000 to BFFFFF -- hence why this demo would be TL/SL only. It's also why using 640x200x16 screws up any herc card if present.

Also there's no vidtan file in that archive...

 

[Great Hierophant]

Its because the Tandy does not actually map RAM to that location, B8000-BFFFF, its only a convenient window that points to the top of the Tandy 1000's memory. The Tandy 1000 TX, TL, TL/2, & TL/3 and RL can be upgraded to 768KB continguous conventional memory, but in that configuration use the top 128KB of conventional memory only for video memory. These systems without the memory expansion and other Tandys can certainly allot more than 32KB for the video, but that actually eats into conventional memory. I/O 3DD and 3DF select the paging modes.

His name is Jim, btw.

How exactly would that work given there's only B8000-BFFFF -- 32k actually mapped to video memory, there's no paging to make the video display using RAM outside B8000 to BFFFF, and 320x200 in 16 colors is just a hair under 32k?

160x200 you can get a whole whopping two pages.... Four pages at 320x200x16? I don't think so Tim. That's 128k -- where would you map it? It's not like there are bank swapping controls. (or a reliable way to even have a bank to swap FROM)

There's a reason the TL/SL only has ONE page of 640x200x16, and that's because they map it from B0000 to BFFFFF -- hence why this demo would be TL/SL only. It's also why using 640x200x16 screws up any herc card if present.

Also there's no vidtan file in that archive...

 

[Trixter]

Also there's no vidtan file in that archive...

I wrote 'search the *.pas files for "vidtan'". I should have written "search all of the *.pas files for the string "vidtan" and you'll find the portions that deal with Tandy/PCjr page banking."

From April to roughly August I'll be adding full PCjr and Tandy support to my graphics library, so if you want to wait until then, that's cool. Currently the "vidtan" portions work with 160x200 mode and support a hidden and visible page; when I'm done, they'll support everything except the TL 640x200x16 modes because I no longer own a TL machine. I'm expanding the library because it's required for the presentation software I'm writing -- long story, and more details will be available at the end of August.

 

[SquallStrife]

His name is Jim, btw.

I believe "I don't think so, Tim" is a Home Improvement quote, rather than an attempt at naming the individual.

 

[blackepyon]

If I understand what is going on here, This is similar to, and a step beyond what Tandy was doing already to get 16 simultaneous colours over CGA, by changing palettes between interlace scans?

Well done, by the way.

 

[dr.zeissler]

What is the best tool for watching .ans files in dos on a tandy 1000 rl/hd ?
acidview does require 286+ and ega.

Thx
Doc

 

[Trixter]

type a:\coolpic.ans

 

[dr.zeissler]

that does work when ansi.sys is loaded...but not very fast and not very handy, but it does the job
I am currently checking how to make this like a slideshow for a folder with ans-pics.

 

[Trixter]

That sounds like a perfect first-time programming exercise.