Please Help me Somebody with DEMUX Gate

[michael1978]

thank you ….


i have just last question

i just dont understand there are 16 BIT input and output
so how i have to make this 16 BIT  to generate signal
i understand DAC and signal generation

ohh Wbahn dont be nervous

[WBahn]

16 bits is just the amount of data contained in each memory location. That has nothing to do with how many bits you need in your DAC. Remember, each memory location represents 16 pixels -- one bit per pixel. So the memory side of your VGA controller will access one memory location and then walk across the 16 bits it find there generating one pixel at each step.

[michael1978]

Hello mr Wbahn
thanks
my english is not good

so i take this from internet


do you see i write THIS IS 16 PIN, then Monochrom have video input and hsyns and vsyns pins
so how is possible to do it now

what i have to do, what i have to build now
everythink is OK, only screen and keyboard i dont know how to connect physical

i hope now you understand me...

[WBahn]

I get the impression you are back in the mode of just grabbing something off the internet and throwing it against the wall and hoping something sticks.

Do you understand each part of that circuit?

For instance, do you know what the two triangle components at the bottom-right are that have signals going into the side of them? What do those signals do? What is their purpose? How do the three components that are driving the InM bus not cause contention (multiple outputs trying to drive the same line at the same time)?

You stated that you understand how to do the video signal generation. Well, as you are generating it you need image data, right? Where does that data come from? The Data RAM. In chucks of sixteen pixels at a time. So you set the RAM address and then leave it alone for the next sixteen pixel values. As you output each pixel on the video lines you walk across the RAM data output value to get the next pixel value.

There are numerous ways to do this. One would be to use a FIFO, but it can also be done with bit masking.

Your video controller is best done using a MCU or FPGA (actually, something like a CPLD is probably more than enough). Heck, you could even use a slightly modified Hack!

Doing it with discrete logic components is certainly doable (that's how it used to be done, after all), but it's a bit involved. You really need to use solid problem solving skills and break the problem down into smaller, manageable chunks.

[michael1978]

hellooo


ooohh i simple dont know, i dont understand

how to connect to monitor Wbahn
i search on google tutorial, i search my head is blocked

let say data ram is 16 pins(OK) so you have 16 WIRE and you need  just one wire input to vga port right?
so how we do it? 16(bit)(pixel) and you have just one 1 input(for black and white color) to vga port and 2 input for HSYN VSYNS

man i am almost finish(i dont want to stop(because i dont know how to connect dispaly and keyboad))

[WBahn]

michael1978 wrote

hellooo


ooohh i simple dont know, i dont understand

how to connect to monitor Wbahn
i search on google tutorial, i search my head is blocked

let say data ram is 16 pins(OK) so you have 16 WIRE and you need  just one wire input to vga port right?
so how we do it? 16(bit)(pixel) and you have just one 1 input(for black and white color) to vga port and 2 input for HSYN VSYNS

man i am almost finish(i dont want to stop(because i dont know how to connect dispaly and keyboad))

You don't just plug a wire from your data ram into a pin on the VGA port and call it good.

You have to generate the correct signals for each of the VGA pins.

The color pins take a signal that varies with time and at any given moment in time the magnitude of the signal corresponds to the brightness of that color component at one particular pixel on the screen. The monitor is constantly scanning across the screen left to right and down the screen from top to bottom. When you provide an HSYNC pulse the scanning is moved over to the left edge, where it again starts moving across the screen to the right. When you issue a VSYNC signal the scanning is moved to the top where it again becomes moving down the screen. Between successive HSYNC pulses you need to provide the correct amplitude signal on the color lines at just the right time relative to the HSYNC pulse so that it maps to the correct location on that line of the screen.

The information that you need in order to determine how big to make the amplitude is what is stored in the Data RAM. So you need to build a circuit that accesses the correct location in the RAM, gets the value from the RAM, and uses that information in order to set the next sixteen amplitudes on the color lines. While that is happening, you need to be getting the next value from the RAM so that you are immediately ready to start providing the next sixteen signal levels because the monitor isn't going to wait for you.

[michael1978]

thanks very much for time to answer me....

i am searching all day how to connect hack computer to display and keyboard
i search all google  nothing to help me

look i dont need a vga

me i just want to connect hack computer to display

what is the easy way to do and to understand

i read book on design you own video game console by andre lamothe
there i see a R2ladder to make a signal

but he show some formula for hsync and vsync but in the end i understand little bit

i dont want to bother , i make you tired with my question

but how to do it, what now about hsync and vsync
i dont know where to start


can you explain me more in detail

[michael1978]

hey my dear
i found in internet
 to build vsync hsync color module


now what i have to do?

[WBahn]

michael1978 wrote

hey my dear
i found in internet
 to build vsync hsync color module


now what i have to do?

I haven't got the faintest idea because I have no idea what this module is that you found on the internet, so I have no idea what it's interface is.

For that matter, you haven't describe how you are planning to modify your Hack hardware to make the screen memory accessible to your display adaptor.

There are multiple ways to do it, so I'm not going to guess.

[michael1978]