Bryan

Think outside the "box"

I want to give everyone an update: I have been working full-time on renovating my house to sell. As many of you know, my wife and I spent 3 1/2 years in Costa Rica and I had a large freelance job lined up that I thought would provide income while we were there. Well, it kinda fizzled due to a lack of interest from the other party and when my wife and I moved back, we were deeply in debt. I bought a cheap fixer-upper house in Michigan so my wife could take care of her mother with advanced diabetes. At first, we were going to live here and slowly work off our debts, but with the rising real estate market combined with a generous offer to live cheaply with friends, it has become important to finish up my repairs and sell the house ASAP for a fresh start. To this end I've been living in a construction zone and maxing out my credit cards to get the work finished and I hope I'm in my final month of this gigantic task (this house was cute, but completely trashed in every way). I'm shipping out current orders as I can make the time, and I hope to resume development of future products as soon as I get my lab set up again somewhere else. I know I still have PMs to answer and I'll fill as many remaining orders as I can, but I'm not planning on ordering any more boards until next year. I just wanted to explain why I dropped out of sight for a little while. -Bryan

Just found out what happened. Due to budget constraints, Rob Wyatt had to swipe the web server computer when setting up his office.

Likewise, I didn't actually think the shirt was for early VCS backers.

I see you got the early backer commemorative t-shirt.

Might I suggest an Indiegogo campaign to pay someone to keep the website online?

I believe it saved an extra transistor per bit cell. With EPROMs, you're basically charging a small floating capacitor acting as the gate of a FET. With no charge present (erased cell), the FET conducts and this is represented by a 1. Once the gate is charged, the FET no longer conducts. UV light can excite the electrons enough that they tunnel through the barrier and discharge the gate (and, they'll discharge themselves naturally over the next 20-50 years).

The AC mixes one or more sources into a single channel because mono output is used far more often in Atari systems than stereo. Two of them could be installed for stereo, but you could also wire in stereo audio directly from TIA and then use an AC to generate an alternate mono signal. To do this, follow the mod described here: http://atariage.com/forums/topic/199461-atari-2600-stereo-mod/?p=2545630 Then run left and right (before the output capacitors) into AC inputs A and B to mix them without affecting the stereo signal.

Sure. An RCA connection is very common for audio. Or, are you asking if the AC board is necessary? It isn't, technically, but it greatly simplifies creating an output that mixes Pokey and SIO audio together (like tape loaders with music).

I deleted my comment about a Rev A ROM. The Tech-Tip was actually talking about the computer OS even though it was included in the 810 FSM. It would be interesting to see if there ever was a Rev A released. Maybe in a prototype drive. One thing is clear from the Tech-Tips, Atari had a lot of problems getting this thing to work right at first.

Here's a (rough) picture of the ROM in the schematic. Notice how they labeled the chip selects on the left as active low, but pulled them high? They are indeed active high, but that makes them incompatible with any 23 or 25 series EPROM I know of. Mask ROMs often have optional inverters on these pins allowing you to pick the polarity. This is how they made all those 2600 games respond to A12 properly. -Bry

Yeah, sorry. That was confusing. I was just bringing up why it doesn't do graphics. I had a 1025 back in the day and I was kinda pissed when I realized it had no graphics mode.

From what I've heard, the Okidata equivalent printer was text-only as well. It would be a fun hacking project to put a gfx mode into the firmware. You might need to add a little RAM too.