Video Chips on Mouser...

[drogon]

SimonJ5 wrote:

There's another example here http://geoffg.net/terminal.html that gives 80 x 24 (ish) into VGA and 44 x 15 (NTSC) or 48 x 18 (PAL) to composite. It uses a through-hole ATMEL chip - does that count?

My own thing is through-hole, so yes

Another thing to look at, although maybe not for the original poster is the video 'card' that Quinn Dunki build for her 6502 Veronica project - http://quinndunki.com/blondihacks/?p=1227

briefly, she used an ATmega324 with external RAM and a tightly controlled assembler loop to take data from the RAM and pass it out via a simple DAC to generate VGA colour graphics.

SimonJ5 wrote:

Something that's been in the back of mind is to see if, rather than communicating via the serial is to use it as a memory mapped device - perhaps with some wait state generation from Daryl's web site.

My particular obsession is with a relatively unknown (outside of the UK) system called the Microtan 65 (from a company called Tangerine) which clocked the CPU at 750kHz and had a discrete logic video generation of 32 x 16. There was an add-on board available which used a stand-alone 6502 running at 2MHz, communicating via a couple of bytes in the memory map to give 80 x 25.

There are a couple of people who are re-casting the original designs using 'modern' replacement components only where absolutely necessary as well as providing lots of information, including circuit diagrams or both the original and new boards. They can be found at http://www.microtan.ukpc.net/. Their latest board is a 'high resolution graphics' card (as called by Tangerine back in the 80s) that gives a 256 x 256 pixel graphics board!

Simon

nice to see other UK systems being mentioned

My Ruby thing is more like a BBC Micro right now with graphics de-coupled from the BASIC (etc.) via the operating system - right now my graphics goes out via serial, but I'm testing an 8-bit parallel interface (through a VIA) to a popular $5 SBC with HDMI output...

-Gordon

[BigEd]

Thanks Simon for the pointer to the Microtan 65! I would like to see a list of recipes for discrete-logic video, as a counterpart to all the other possibilities - nice as they are - which use dedicated video chips, or microcontrollers.

Here's a photo of a Microtan 65, taken at Snibston in 2013, at a VCF retro computing event:
https://photos.app.goo.gl/mg6roJAr8zc1p4EU8

[Chromatix]

A complication in recent years is that conventional VRAM chips are no longer manufactured. If they were, that would greatly simplify the problem of generating fast enough output for a good SVGA signal while still being able to update the framebuffer contents.

However, I have ideas for a bitplane-based design that can use ordinary 55ns SRAM chips and, at least in theory, be built up incrementally from monochrome to 8-colour to 64-colour to 8-bit palette (the latter requiring a faster SRAM chip for the CLUT) and beyond. With suitable component choices it may be able to support a 48MHz dot-clock, enough for 800x480 @ 75Hz, but can also be used for the slower dot-clocks appropriate for composite video. I'll start a thread in the Hardware section to explain how it goes.

[DerpymanMT]

How would I connect the arduino uno to the VIA chip, (im pretty new to the whole, major circuit designing thing.) I am looking at The First Great 6502 Project, and I will check out the second project with the LCD display, Ive already tested the arduino TVout library, and already hooked it up to my tv and got it working. And im going to very honest, when i first got my circuit kit the breadboard broke, and we never got around to replacing it... So... I was never able to fully learn about Circuits, and I had many other things at the time, so i couldnt really learn. but I am getting classes soon, and I do have a good understanding of circuits, (but never fully understood transistors ) Plus my uncle is getting me lessions... But enough of that, What would you mean Bit-bang and how would i do it?

[GARTHWILSON]

DerpymanMT wrote:

How would I connect the arduino uno to the VIA chip, (im pretty new to the whole, major circuit designing thing.) I am looking at The First Great 6502 Project, and I will check out the second project with the LCD [...] What would you mean Bit-bang and how would i do it?

The 6502 primer has a lot of the answers you'll need. It has a page on displays, and the circuit potpourri page has a section on interfacing to intelligent character displays, with a link to working sample code. In the RSTLCD routine, it has more code than you might think you need; but we found through experience at work that the extra is needed to always get a dependable reset and setup under all conditions; so don't ignore it. Shown at the end of the displays section of the circuit potpourri page is a few seconds of video showing a 64x128-dot graphic LCD interfaced by SPI, with a link to working sample bit-bang code to drive it.

"Bit bang" means the clock and data lines are manipulated in software rather than dedicated hardware. The 6522 VIA has a synchronous-serial port for which I show various uses farther up the circuit potpourri page, but it's not quite SPI-compatible, at least not for all the SPI modes. Bit-banging SPI and I²C is really easy though, as they don't have the strict timing requirements that a UART has. (The I²C section of the circuit potpourri page also has a link to working sample code to bit-bang I²C.)

If you use SPI or I²C over a connector, let me recommend our I2C-6 proposed hobbyist-friendly connector standard for small I²C modules, suitable for common perfboard, or our SPI-10 proposed hobbyist-friendly connector standard for small SPI modules, also suitable for common perfboard. We wanted to be able to make small modules that plug in, similar to the SD-card idea, and make it easier to share designs and perhaps even hardware in the future, with a connector that's hobbyist-friendly. A few of the forum members here have made their own computer boards with SPI-10 and I2C-6 connectors. On the front page of my site (linked below), you'll see that one of the things I offer is a tiny SPI-10 serial flash module.

[DerpymanMT]

The UART that i am using is the MAX3100 chip, and it has TX and RX pins, should i connect it to that just to test it out. I dont have the components til tuesday, so I will have to wait till then but in the mean time I could program the Arduino UNO to accept the data from the UART. Is that even practical? I mean i know the UART can talk using Serial data, but to use it to transmit Video commands? I dont know... I am working on making the Arduino Into a video card with a fan and heat sink (I know its a lil overkill, but it will hot a lil...)

[drogon]

DerpymanMT wrote:

The UART that i am using is the MAX3100 chip, and it has TX and RX pins, should i connect it to that just to test it out. I dont have the components til tuesday, so I will have to wait till then but in the mean time I could program the Arduino UNO to accept the data from the UART. Is that even practical? I mean i know the UART can talk using Serial data, but to use it to transmit Video commands? I dont know... I am working on making the Arduino Into a video card with a fan and heat sink (I know its a lil overkill, but it will hot a lil...)

You can not overheat an Arduino. You will never need a fan on one.

You can send video commands to it via serial (or parallel) that's the same as was done decades back with e.g. Tektronix 4014 terminals. It's also the same mechanism the (6502 based) BBC Micro used, although that was all done on the same CPU, but was expanded to have 2nd processors to run the application with the base system doing graphics sound, etc.

It's also the same principle I use on my Ruby system.

Your code on the 6502 just says: "draw line", or "draw filled circle", move sprite 12 to X,Y, ... and the code there translates this into high level commands and sends that command to the system doing the drawing. That system then action it.

-Gordon

[DerpymanMT]

So here is my somewhat Weird but functional Video Card!
It'll communicate through the TX and RX pins on the Arduino and the MAX3100 UART chip,
https://ibb.co/qJw3n0m

I didn't have a Jack for the Composite video so I chopped up an old Xbox 360 Composite cable and got the video plug, My TV does support composite (as the HDMI ports on it are busted)

I am using the VIN pin to supply the voltage from the main board to the Arduino.
The next thing I have to do is to try and get the UART chip (Which I'll hopefully get tomorrow) to transmit the Video Data to the Arduino Uno, and program the arduino to under stand what the UART is saying!

Thanks for your help!
(I'll most likely keep posting in newbies for a while till i get the hang of all this)

[cbmeeks]

Seems like there is enough demand for someone to come up with a CPLD video chip solution. I know FPGA would be bigger/faster but seems like an ATF1508 (which can handle 5V) and some SRAM could become a VGA framebuffer.

That's what I hope to build when my CPLD/HDL skills get better.

[jds]

cbmeeks wrote:

Seems like there is enough demand for someone to come up with a CPLD video chip solution. I know FPGA would be bigger/faster but seems like an ATF1508 (which can handle 5V) and some SRAM could become a VGA framebuffer.

That's what I hope to build when my CPLD/HDL skills get better.

That sounds like a very worthwhile project. The constraints of a CPLD would help focus the project, and the 5v is a definite advantage. Lots of choices to be made and in the end everyone around here has different goals.

I used the ATF1508 for glue logic and ROM in my breadboard project, the ROM really filled it up but I could get enough for testing or a simple monitor, which I think is quite impressive. I used verilog, which requires a license from Atmel, but now there is a tool called POD2JED that lets you use the free Altera Quartus II tools, which could be useful.

[cbmeeks]

Yeah, that's a good point too. Using a CPLD is much more restrictive than a medium or high end FPGA. Plus, the PLCC-84 just seems more like a vintage chip package to me. Not sure why. At least something you would see in a Mac or Amiga.

[pbj]

I have used Propeller chips connected over serial so it requires a single I/O from the host micro and you only need a current limiting resistor to go from 5V to 3.3V logic. Because it is simple serial you can have the video off-board altogether and even at a great distance too. The P1 Propeller chip is limited with memory but generates VGA and NTSC easily and you can have a tiled graphics display with bitmap graphics of around 640x360 mono over color tiles.

However, now that the P2 is available you can have full 8-bit color with full 640x480 VGA resolution. Many years ago I made an ARM module the size of a thumbnail that generated VGA but then I upgraded to the P1, and now maybe I might make a small module with the P2. Before all that I did do it with CPLDs and RAM, but a micro has the advantage in that it can be a GPU and render fonts and graphics over serial.

[cbmeeks]

I don't believe the P2 is fully available yet, is it? I know there have been some runs of a development board from Parallax. But they are around $150 IIRC.

One of the forum members created a small dev board (I have one) that I think is pretty cheap but very limited in quantity. The board I have isn't populated and I don't have the actual P2 chip yet.

The P2 could be a major contender for many things. Especially people who don't want to go FPGA but still need some major power (and a simple language that doesn't require expensive licenses).

[pbj]

cbmeeks wrote:

I don't believe the P2 is fully available yet, is it? I know there have been some runs of a development board from Parallax. But they are around $150 IIRC.

One of the forum members created a small dev board (I have one) that I think is pretty cheap but very limited in quantity. The board I have isn't populated and I don't have the actual P2 chip yet.

The P2 could be a major contender for many things. Especially people who don't want to go FPGA but still need some major power (and a simple language that doesn't require expensive licenses).

I have 50 of the new RevB P2 chips and about 15 of RevA as well as 3 eval boards and my P2D2 modules plus I can order more chips as needed at this stage. Creating a small pcb to handle NTSC/VGA/HDMI is very simple to do.

[cbmeeks]

pbj wrote:

I have 50 of the new RevB P2 chips and about 15 of RevA as well as 3 eval boards and my P2D2 modules plus I can order more chips as needed at this stage. Creating a small pcb to handle NTSC/VGA/HDMI is very simple to do.

Well, I believe you are the exception, not the norm.

What I meant was I don't believe you can go to Mouser or Digikey and buy a single P2 at the moment. Not sure when that will happen.

But yes, creating a small board with a P2 for video should be fairly trivial (relatively speaking...video generation is not trivial by nature). Assuming one can easily get their hands on one without spending a lot of money.