Anyone know what this cartridge / circuit board is?

[Blocky]

I know this plugs into the cartridge slot on ATARI 400/800 but I have no idea what it is.

 

I know it's from back in the day or at least, before the 1990's.

 

There's an on/off switch on it. It says "ARRBEE®" on it and the switch says "JAPAN MS-550A"

 

What gets me about it is, the lid on the Atari cannot be closed once this thing is inserted.

 

What is it?!

 

 

[_The Doctor__]

It may be a cartridge ROM lock device making internal ram appear to be ROM so programs can run from ram that were originally on cartridge rom.

[Blocky]

OK thanks. I can't find any photos of another one anywhere, or any other info.

[reifsnyderb]

58 minutes ago, Blocky said:

I know this plugs into the cartridge slot on ATARI 400/800 but I have no idea what it is.

 

I know it's from back in the day or at least, before the 1990's.

 

There's an on/off switch on it. It says "ARRBEE®" on it and the switch says "JAPAN MS-550A"

 

What gets me about it is, the lid on the Atari cannot be closed once this thing is inserted.

 

What is it?!

 

 

If you have the device in your possession, you can probably get the chip number off of it.  With the chip number, we can probably figure it out.  So, if you can get the chip number, please post it.

[_The Doctor__]

seen it before, just look at what pins on the cartridge interface are connected and you can verify.

 

 

Edited April 28, 2023 by _The Doctor__

[Blocky]

The only thing I can see on the chip is a faint word in the bottom right corner ending in "PURE".

 

It looks like it says "STRCAPURE" or something.

 

The pins look like it's 13+14 at the front and B+R+S at the rear.

 

Or if that's in reverse then it's 2+14+15 front and P+R at the rear.

 

I don't know what I'm doing lol

Edited April 28, 2023 by Blocky
Spelling mistake.

[+5-11under]

I have no idea about the Atari computers, but...

 

RD4 and RD5 are connected together. The go to the switch. The switch then goes to pin 8 of the chip. Pin 9 and 10 of the chip are connected to R/W.

The chip is pretty likely a 14 pin logic chip. Pin 7 is ground. Pin 1, 2, 4, and 5 are also grounded. Pin 14 is VCC. Pin 12, 13 are also connected to VCC. Based on pin 1, 2, 4, 5 grounded, I'm thinking an OR or AND or similar chip (NOR, NAND). If yes, then pin 9 and 10 are inputs, and pin 8 is the output. The logic is then RD4 = RD5 = R/W ? R/W. So, it's a NAND most likely, acting as an inverter?

 

That's if I got my directions correct. Bloody confusing working with 2 sides of cart slots and chip pinouts from both sides. Also, like I said, I could only guess what RD4 and RD5 are (or could search it, I guess  ). Definitely that would help in the understanding.

 

Edit: so RD4=RD5 = invert of R/W, but only if the switch is activated!!!

[Blocky]

Yeah it is confusing, I don't even know which way around this plugs in, I assume so "Off/On" is facing forwards. 🤷‍♂️

 

My dad worked in a shop selling Atari games back in the day. He got loads of free games from there. He also wrote a few games. I reckon this might be a custom made thing. I mean he wasn't the average user or gamer, he was really into it.

Edited April 28, 2023 by Blocky

[Peri Noid]

Look at the cartridge slot pinout and trace GND and +5V traces to the chip. I suspect that one way it will be logical, the other - not. The logical orientation will be the one. 

[+5-11under]

21 minutes ago, Peri Noid said:

Look at the cartridge slot pinout and trace GND and +5V traces to the chip. I suspect that one way it will be logical, the other - not. The logical orientation will be the one. 

See my post. Pin 7 of the chip goes to ground, pin 14 goes to VCC. It's easy to figure out the directions after that... see my post. RD4 and RD5 are for memory selection, and R/W is for reading and writing. Probably basically what The Doctor said right away... if not, then something similar. Easy enough to search for the answers.

[Blocky]

If the Atari 800 lid won't close when this is plugged in, how is it used?

 

I really need to plug it all back together and delve deeper.

[Rybags]

You'd have to use something to hold the lid switch closed.

To use the cart a copy of a linear mapped cartridge (most are) would be needed.

The board would need to be switched off during loading.  Then a prompt to switch the board on, then run the cartridge.

Such a board these days is almost obsolete since practically all the old cartridge games have had the protection removed and can be run from Ram without issue.

[dmsc]

Hi!

 

9 hours ago, Blocky said:

I know this plugs into the cartridge slot on ATARI 400/800 but I have no idea what it is.

What is it?!

As The Doctor said:

9 hours ago, _The Doctor__ said:

It may be a cartridge ROM lock device making internal ram appear to be ROM so programs can run from ram that were originally on cartridge rom.

 

Very simple indeed, this is the schematic from the pictures:

Have Fun!