- I agree with the author: home grown video systems are cool. Very interesting. I want one
- Yeah. You should add both. The BASIC appears to deserve it.
This is a bit off topic, at least for this thread, but I am doing some similar activities related to pocket computers.Sidebar:Back in the day, what I really wanted was a Model 100 by Tandy. I have one now, and yeah. It would have done the work back then. Well.
My use case was manufacturing. Actually still is! I have an opportunity to make some parts similar to ones I did then. At the time, I used a combination of a Tandy PC-6, I believe? The folding one. And also a Casio scientific.
The Tandy had just enough to be useful, but no graphics. Only 20 character, one line display too. Ugh.
But that was enough to help lay out parts and crank out some g-code, which I would just type into a machine and run.
Well, little didnI know, but SHARP was flat out killing it in this space. They got really good at designing little, fast organizers that ran an bit CPU of their own design I think, and button cells!
Their displays were often super too. Clear, fast, respectable pixel counts.
The SHARP G850VS is basically a whole darn workstation. Battery requirements went up to AA cells, but worth it!
Display has 20x5 lines too. Pixel addressable.
But get this!
It has a huge system ROM containing:
BASIC with graphical, scientific, statistical and robust logic commands.
System Monitor
Z-80 Assembler
C Compiler! ! ! (Seriously?)
PIC Assembler
And one other pseudo machine assembler for education I do not fully understand other than the consensus it it being useless.
System Bus, like for cartridges or and / dock.
10 Pin GPIO block, similar to the Raspi machines.
IR comms capability.
That is nuts! And back then it was easy to miss this kind of thing. No Internet meant a lot of us just did not get info. Heck, I learned 6502 out of the magazines in the grocery store magazine racks!
I am on the hunt. And they are not too hard to find right now, so I really just gotta save my pennies and pull the trigger on a good one.
That kind-of capability would have enabled a little CAM system with back plotting to verify g-codes!
Seems to me you found enough here in your exploration to want the same thing. Flesh it all out and go! Bet you it ends up worth it. :)End SidebarVery enjoyable write up, BTW.
- I used Hyperterminal once. It is too basic. I just needed serial comms to bring up a server, so no big deal.
It was nice to see it in the box, so to speak.
- We have a small expansion on that bit of detail:
>The GPU also supports a text mode where the bytes of video memory alternate between a color byte and a code point representing a text character. The color byte is used with the second video DAC to represent two 8 color values for foreground and background. The text mode can also support a high res graphics mode with two pixels per byte of video memory.
That explains a bit more. 2 pixels per byte and then here comes 416! That number is odd, meaning they have done some thing unique, IMHO.
So we get 4 bits per pixel. 8 colors uses up three of them, so that last bit must combine pixel data in some novel way.
4 dither patterns goes into 8 colors nicely, 2 colors per pattern.
It could mean each pixel can be one of 8 colors with no constraints.
Or, each pair of pixels is assigned a color, which would come from the 8 already defined. And maybe the order is toggled in some regular way.
Oh, wait! Maybe he did what Woz did on the Apple 2!
Looks like this:One byte has a data form like this: DD_CCC_CCC CCC = colors 0 through 7 for the even and odd pixel DD = dither patterns 0 through 3 which make use of the scanline counter and pixel order in the byte 00 = pixels are assigned colors as given by their respective CCC fields. 01 = pixel color order swapped on odd lines 10 = pixel color order swapped on odd lines 11= both!
...where the two zeroes are bits and the CCC fields are for the odd and even pixel in that byte.DD = 00 Pixels go by color at all times 0123456701234567 line 0 0123456701234567 line 1 A line looks like this: 00_CCC_CCC 00_CCC_CCC 00_CCC_CCC 00_CCC_CCC 00_CCC_CCC 00_CCC_CCC 00_CCC_CCC 00_CCC_CCCFor brevity and clarity I am just going to write pixel color numbers 0 through 7 rather than all those bits.
And I am on Mobile, so I will also ditch delimiters. I think it remains clear enough. Hope so!00 01_23_45_67_01_23_45_67
Ok, here we go!00 0123456701234567
Frankly, if this is what they did, It is very expressive. I would get a lot out of a mode like this. Dithers can be pretty expensive either to compute dynamically, or in terms of stored images.DD = 01 -- Horizontal Dither Odd 0123456701234567 line 0 1032547610325476 line 1 . . . DD = 10 -- horizontal dither even 1032547610325476 line 0 0123456701234567 line 1 . . . DD = 11 Both odd and even dither! 1032547610325476 line 0 1032547610325476 line 1 . . . Using just black and white pixels: 00 🟈0🟃0🟈0🟃0 🟈0🟃0🟈0🟃0 🟈0🟃0🟈0🟃0 🟈0🟃0🟈0🟃0 01 🟈0🟃0🟈0🟃0 0🟃0🟈0🟃0🟃 🟈0🟃0🟈0🟃0 0🟃0🟈0🟃0🟃 10 0🟃0🟈0🟃0🟃 🟈0🟃0🟈0🟃0 0🟃0🟈0🟃0🟃 🟈0🟃0🟈0🟃0 11 0🟃0🟈0🟃0🟃 0🟃0🟈0🟃0🟃 0🟃0🟈0🟃0🟃 0🟃0🟈0🟃0🟃These patterns can be applied on a byte basis! It is close to the next best thing if we can't have 16 colors.
What I meant by "he did what Woz did" was put those high bits to good use. On the Apple, Woz shifted pixels a bit to deliver a 6 color high resolution graphics screen. I am sure you all have seen how expressive Apple artifact graphics can be.
It is way more than what one can do on a 4 color screen, particularly given the pixels get fatter. One trades a lot of detail.
Now, this scheme has those same attributes! Resolution potential remains high, just like the Apple high resolution screen. Nice, small pixels.
But now the number of apparent screen colors goes way up! Those pattern variations will yield tons of fairly automated, consistent color impressions.
Instead of a 8 color screen, or a 16 color one, it is as if more like 24 or even maybe 32 colors are available.
This is all a big guess of course. But it is a somewhat informed one that takes TTL possibilities into account as I understand them.
BTW, if this ran at TV NTSC frequencies, and offered 320 pixels per line, or offered some combination of pixels that repeats evenly into the NTSC color cycles, given that odd number of pixels, it would be gorgeous! Just saying.
- Thanks for the detailed explanation. If that's what it is doing then it would indeed be interesting and pretty unusual for a modern day homebrew system. I too wondered if maybe the dither pattern referred to something like the Apple II's artifact colors but dismissed it because artifact colors require composite video output to work and there was no explicit mention of composite.
- Here is a sample image from the project site. I can't tell if this jives with your explanation. Also, I am not sure if dithering is the same as artifcating which is what I used to see on Apple II and Atari Hi-Res games sometimes to get extra "colours" out of monitors and tv sets.
https://hackaday.io/project/164212/gallery#0f87e94323e101952...
- Procomm Plus and that scripting language was awesome for automating Symix MRP software.
Great program.
- Go Best! I have purchased a few times. You can be sure you will get exactly what was advertised.
And if you are suggested an item, consider it. It was suggested for good reason
- Go Best! I have purchased a few times. You can be sure you will get exactly what was advertised.
And if you are suggested an item, consider it. It was suggested for good reason
- https://www.1001fonts.com/flexi-ibm-vga-true-font.html
https://www.1001fonts.com/flexi-ibm-vga-false-font.html
Both by a friend of the site.
The color choices on that page are excellent! Bookmarked for the future.
- So good! I love that era of artifact graphics.
I love the bit of texture such techniques tend to add to an image. The CRT mask is similar when viewed closely, or even at normal distance, when you are gawking at a coarse one.
- I was just looking for this!
- More
Truly impressive machines, but vulnerable to the classic Sharp durability issues. I'm still hopeful I can bring it back :)