Mystery Atari 400 modification?

[Tara]

Years and years ago, I picked up a 400 back at a thrift store, and it's one of 3 that I have. I literally used it for a doorstop for a while since the RF cable was snipped, and I didn't have a way to test it then.

 

What made this 400 stand out from the others is that it has what looks like a 25-port SCSI or serial port on the left side, obviously hacked in. I've included some pix of this, if anyone can figure out what this was added for

 

External keyboard?

SCSI (yeah, right!)

some sort of serial/parallel port for a printer?

 

Years later, I was finally knowledgeable enough to crack it open and plug another RF cable directly into the board, so it turns out it works fine. A couple of keys don't seem to work all the time, but it doesn't seem to be a permanent problem

 

Any thoughts on what the port is?

 

As a side question, has anyone ever hacked a 400 so that it can take 5200 carts? That'd be a solution to those crappy joysticks...

 

-Tara

[+warerat]

Years and years ago, I picked up a 400 back at a thrift store, and it's one of 3 that I have. I literally used it for a doorstop for a while since the RF cable was snipped, and I didn't have a way to test it then.

 

What made this 400 stand out from the others is that it has what looks like a 25-port SCSI or serial port on the left side, obviously hacked in. I've included some pix of this, if anyone can figure out what this was added for

 

External keyboard?

SCSI (yeah, right!)

some sort of serial/parallel port for a printer?

 

Years later, I was finally knowledgeable enough to crack it open and plug another RF cable directly into the board, so it turns out it works fine. A couple of keys don't seem to work all the time, but it doesn't seem to be a permanent problem

 

Any thoughts on what the port is?

 

As a side question, has anyone ever hacked a 400 so that it can take 5200 carts? That'd be a solution to those crappy joysticks...

 

-Tara

 

Looks like it's connected to Ports 1 and 2. So it's some extension to PIA Port A and a few other signals (triggers?). Without knowing what software drove it or what was connected to the other end it could have been a parallel port or any other kind of custom I/O device.

 

An 8-bit can most certainly be hacked to take 5200 carts, but the problem *is* the joystick. The software for the 5200 is written to look for them connected to POKEY, whereas on the 400/800/XL/XE the joysticks are connected to the PIA, which does not exist on the 5200. It is feasible to make an adapter to play 5200 games on the 8-bit, but the wiring would be messy.

[Rybags]

Probably some sort of printer interface, likely RS-232 serial.

 

A friend made one which initially used 2 ports, then one.

 

With timers on POKEY, it's entirely feasible to do your own bit-level controlled I/O at varying rates via the joystick ports.

 

Likely this one probably would have worked at some low bit-rate like 1200 or 2400 bps. Entirely possible as well that it could have supported a modem. Low bit rates not a problem of course, since printers only did 40 cps or so, and most modems in the day were 1200 bps or less.

 

Strange though that they chose to use ports 1/2, 3/4 would be a much wiser choice - although such a setup still allows normal use of the joysticks.

[Noelio]

It could actually be a do it yourself parallel as in the article below...

 

http://atarimagazines.planetmirror.com/v2n...rinterface.html

 

Then again maybe it was just a torture console I/O used to control the rate which a platform with a human strapped to it would descend into a large vat of sulphuric acid when playing othello.

The Atari 400 would be good for it as the membrane keyboard sure is more acid resistant than the other machines. Tehehehe!

[mimo]

As a side question, has anyone ever hacked a 400 so that it can take 5200 carts? That'd be a solution to those crappy joysticks...

 

 

That would be pretty pointless as the games have already been hacked to work on the 8bit computers, for example Dig Dug, but if you need 2 fire buttons you are pretty much screwed on the 400/800/XL/XE until somebody can get a 2button stick working and the software re-written.

However you will need SIO2PC or a disc drive to use them

[sup8pdct]

Years and years ago, I picked up a 400 back at a thrift store, and it's one of 3 that I have. I literally used it for a doorstop for a while since the RF cable was snipped, and I didn't have a way to test it then.

 

What made this 400 stand out from the others is that it has what looks like a 25-port SCSI or serial port on the left side, obviously hacked in. I've included some pix of this, if anyone can figure out what this was added for

 

External keyboard?

SCSI (yeah, right!)

some sort of serial/parallel port for a printer?

 

Years later, I was finally knowledgeable enough to crack it open and plug another RF cable directly into the board, so it turns out it works fine. A couple of keys don't seem to work all the time, but it doesn't seem to be a permanent problem

 

Any thoughts on what the port is?

 

As a side question, has anyone ever hacked a 400 so that it can take 5200 carts? That'd be a solution to those crappy joysticks...

 

-Tara

 

It could be a parallel printer port but it could also be a port for an eprom burner. Here is Australia, an electronics mag did one that had the data lines interfaced directly to what ever held the data and the address and programming pulse were done on the burner it self. all that was required was a single pulse from the controller.

In fact, one Aussie made monitor for the 800 had the software built in to use this burner. it was called the john Nichols monitor.

 

James

[Rybags]

That's a thought.

 

But, 2 ports only allows 8 bits of output, so I'd suspect if it's the case that only 2 are wired in that it would be serial.

 

Although, it is using a female plug which is normally what you'd have as a parallel port.

 

Regardless, it's someone's homebrew, so he could use it as a launch system for sea to air missiles if he wanted.

[Rybags]

Hack a 400 to become a 5200?

 

That's another thought - surprised nobody's attempted it yet.

 

Theoretically, a heavily modded computer could have a 5200 cart port wired in.

 

Then, you'd need a switchable OS/BIOS and means of remapping some of the I/O chips.

 

But, kind of a long-winded pointless way of having the "privelage" of being able to use a 5200 analog stick on the computer.

[sup8pdct]

That's a thought.

 

But, 2 ports only allows 8 bits of output, so I'd suspect if it's the case that only 2 are wired in that it would be serial.

 

Although, it is using a female plug which is normally what you'd have as a parallel port.

 

Regardless, it's someone's homebrew, so he could use it as a launch system for sea to air missiles if he wanted.

 

It appears to me that 3 ports are used. follow the traces to pins 1-4 of each joyport

Purple, blue, green and yellow appears to go to joyport 3

orange red, brown, black to port 2

yellow grey brown, blue to port 1.

Is how I read it.

 

James

[Rybags]

Looking again, that sounds right.

 

Cheap and easy way to use an industry-standard printer too, considering the ripoff prices most Atari branded peripherals had in the day.

[+Larry]

Probably a printer port, BUT a friend of mine had an 800 with a DB-25 connector on the left side that connected an external keyboard that was sold in the early 80's.

 

Since the 400 had one of the "10-worst keyboards" maybe this could be a keyboard connector? (Presume the joystick ports could be used to pick up the key presses?)

 

-Larry

Edited January 16, 2008 by Larry