Dear Amazing Gurus at the Uzebox forum,
Warm greetings from Finland, this is Panu from VLSI Solution! One of our customers told us about you and, wow, you sure have an awesome product and community. I could have watched those videos of your projects at YouTube for hours!
In the 1980's I've sure inserted my share of coins into Galaga, Bomb Jack and other games machines of the era. And from those memories I got what seemed, and still seems to me like a great idea. A few years ago, we were designing this new SPI SRAM memory chip, because our customers needed one for a project. And at a meeting, our CEO asked if we had any other ideas for the product. And so I said that if we just add a couple of counters inside, we could make a pattern generator that could be useful for "various purposes". He said that should be ok, if indeed it was "just a couple of counters" and didn't make the chip a testing nightmare.
When we got the first chips, I immediately proceeded to make a video output from that pattern generator using a Xilinx XC9536 CPLD and a few resistors, much like what you have in the Uzebox. I actually came to the lab during the weekend and wrote the configuration for a minimalistic NTSC modulator on that tiny CPLD. When our CEO saw it, he asked if we could fit it inside our IC. And I said, sure, its something like 10 to 20 flip-flops. But with a little more, we could make it much better. He asked how much better, and I said full color (my demo had 14 colors - sync level, burst level and 14 indexed colors formed with VHDL combinatorial logic statements). Of course we would need to put a DAC inside, but no problem, our company is expert with DACs.
He asked if those additions would blow up the circuit area. I said: "absolutely not, it's just a couple of registers to set things like line lenght and number of lines". He said: "No, I want you to really think about this, think what should go inside and present it at the next staff meeting, we'll consider it then."
And so I did.
What we now have is the VS23S010D-L chip getting in production, that has an integrated video DAC, 128 kilobytes of SRAM, any amount of which can be assigned to be video memory, xtal oscillator, internal PLL clock multiplexer, digital PAL/NTSC modulator and the necessary counters and logic to get bits from the SRAM and into the modulator. It's a bit more fancy that what I first conceived, but much more flexible. You can set the start address of pixel data for each line separately so you can duplicate lines and create horizontal/vertical scrolling effects. And you can have many different prototypes for a line - those are what forms the sync, burst and background areas. You can select the number of bits you want for the color components, from 1 to 20 bits per pixel. Obviously you can set the length of lines, number of lines and the resolution. There's even a block copy engine.
It's still true to the original design goal of keeping the circuit area to the minimum. We don't have indexed palette memory or even RGB conversion matrix - either of those would blow the amount of logic to intolerable levels. What we have is flexibility, high level of intergration and really low cost. So I hope it might be useful for people like you who, it seems, can appreciate the best of the good old days.
Back in that meeting I told you about earlier, I remember asking: "You know, I can't guarantee that anybody would want to buy this in the end." And my boss replied: "Don't worry about it. Nobody else makes a chip like this anymore, and these speciality chips find their way to the people who need them." So that's what I hope might happen here.
And if not, I will take consolence from my boss's final remark: "In any case, it's still a good serial SRAM."
Should you need any help with samples or getting the chip working, I'm available at http://www.vsdsp-forum.com
, especially at the VS23S010 Forum (http://www.vsdsp-forum.com/phpbb/viewforum.php?f=14