How to Make New PBI Devices

[+bob1200xl]

I think we have been here before... Is there a place where we keep such things? I only have it in hardcopy - how do we get it scanned and converted? And stored where everyone can find it?

 

Bob

 

 

 

If the ANTIC article is too complex, try a Supra MicroPort. It will give you basic decoding on the PBI. Add a latch and you're set.

 

Anyone have the manual for the MicroPort? I picked one up used many years ago, but no book.

[kurtm]

Does the machine constantly poll the PBI? That would be grossly inefficient, from a systems design standpoint. I would have thought that it was interrupt-driven. Even still, using an interrupt would probably be a better way of doing things with this, since this whole thing is meant to be a black-box to make any device that can attach to the PBI, and, as such, it should be designed as correctly as is possible. If it is interrupt-driven, it will ensure that future devices won't have performance hits from waiting around for polling.

 

It polls on boot. After that, it is assumed the device has installed a handler. I'd need to review the Antic and other documentation, but I think when an interrupt is generated by the PBI, the mechanism essentially polls all PBI devices by calling each routine in turn. The device that caused the interrupt needs to detect that it did so and act upon it, otherwise it needs to pass along to the next device.

[UNIXcoffee928]

You do not need a ROM.

 

Use 74HCxxxx devices. Low current, fast enough, cheap. Get a manual for them.

 

The decoder only activates the output when the inputs match a certain pattern. You set the pattern and anytime the inputs are as selected, you get an output signal. This output signal sets the latch on the data bus which drives the 7-segment display.

 

It's a PCB edge connector. 50 pins. .100inch spacing. Yes, hard to find...

 

Bob

Now, this is more like what my intuition was telling me, initially. I'm guessing, though, that this method, versus the other method is equivalent to Rybags' terminology regarding a "Proper PBI Device", versus a "Device Hanging Off of the PBI Port"...

 

 

So, I guess that to conform with the PBI spec, for multiple devices, a Proper PBI Device is a Smart-Device, with it's own handler onboard, and if there is no onboard handler, then it doesn't play nice with other devices, but will work OK as a single device, and requires some type of extrinsic disk handler.

 

Am I on the right track?

 

 

[Rybags]

If the "device" is just an I/O block that e.g. lives at $D700 or probably even within $D1XX (except $D1FF), then you should get away without any ROM.

 

As an example, the RAM 320XL does shadowing (ie simulation) of the PIA so it knows what PORTB is doing.

 

If you used an XE it'd be a bit easier - they provide the $D1XX select signal on the ECI.

Edited July 13, 2011 by Rybags

[+bob1200xl]

I can't follow what you just said... The PBI protocol allows you to add devices in both HATAB and SIO without using system resources. But, it's a Parallel Buss Interface, to complement the Serial I/O. Use it however you like. There are no 'PBI Police'.

 

Bob

 

 

 

You do not need a ROM.

 

Use 74HCxxxx devices. Low current, fast enough, cheap. Get a manual for them.

 

The decoder only activates the output when the inputs match a certain pattern. You set the pattern and anytime the inputs are as selected, you get an output signal. This output signal sets the latch on the data bus which drives the 7-segment display.

 

It's a PCB edge connector. 50 pins. .100inch spacing. Yes, hard to find...

 

Bob

Now, this is more like what my intuition was telling me, initially. I'm guessing, though, that this method, versus the other method is equivalent to Rybags' terminology regarding a "Proper PBI Device", versus a "Device Hanging Off of the PBI Port"...

 

 

So, I guess that to conform with the PBI spec, for multiple devices, a Proper PBI Device is a Smart-Device, with it's own handler onboard, and if there is no onboard handler, then it doesn't play nice with other devices, but will work OK as a single device, and requires some type of extrinsic disk handler.

 

Am I on the right track?

[sloopy]

You do not need a ROM.

 

Use 74HCxxxx devices. Low current, fast enough, cheap. Get a manual for them.

 

The decoder only activates the output when the inputs match a certain pattern. You set the pattern and anytime the inputs are as selected, you get an output signal. This output signal sets the latch on the data bus which drives the 7-segment display.

 

It's a PCB edge connector. 50 pins. .100inch spacing. Yes, hard to find...

 

Bob

Now, this is more like what my intuition was telling me, initially. I'm guessing, though, that this method, versus the other method is equivalent to Rybags' terminology regarding a "Proper PBI Device", versus a "Device Hanging Off of the PBI Port"...

 

 

So, I guess that to conform with the PBI spec, for multiple devices, a Proper PBI Device is a Smart-Device, with it's own handler onboard, and if there is no onboard handler, then it doesn't play nice with other devices, but will work OK as a single device, and requires some type of extrinsic disk handler.

 

Am I on the right track?

 

it wouldnt necessarily need a handler on board, that can be loaded from disk if need be, but the PBI header would need to be in ROM...

 

once the PBI header is in ROM the rest is as you wish...

 

sloopy.

[Joey Z]

in order to interface a 7 segment display to the PBI you would need to use an 8 bit latch with the outputs connected to the 7 segment display. you would then need some chip select logic. this can easily be done with a multi input AND gate for active-high chip select or multi input NAND gate for active low chip select plus some inverters on the inputs to hardwire it to work with a certain memory address. you also need to include the write signal in this chip select decoder so that when the address is correct AND the write signal is active, the latch will latch the data on the data bus (of the PBI) thus saving it and displaying it on the 7 segment display.

 

to access this from basic, all you would need to do is POKE the proper value into the proper address. be sure not to use an address that conflicts with os variables or other io devices. with this configuration each bit of the data byte POKE'd would control one of the segments of the display. you could use the 8th bit for a dot on displays that support it

 

in this case you could just have it overlap system ram. multiple receivers on a bus is fine (ram and 7 seg latch). whatever you do though, if you make an input circuit with switches DO NOT overlap it with system ram. multiple transmitters on a bus is NOT fine.

 

I am not sure what kind of logic levels are used on the PBI but make sure they match the logic chips (if TTL then use 74/74HC/74HCT series, if CMOS then use 4000 series). I also don't know the pinout of the pbi (sorry, too lazy to look) but if the correct signals are present, this would work just fine. also with this design, you wouldn't even need a handler. it would just require a simple memory write (ie: POKE).

 

I am assuming you know enough about electronics to figure the rest of this out on your own, but if you have any questions, go ahead and ask me. I may only be fourteen years old, but I know more about electronics than most people.

 

I hope this helps.

ATARI PBI 7 SEG INTERFACE BLOCK DIAGRAM.bmp

Edited July 13, 2011 by Joey Z