I successfully programmed my Protel 8000 chassis

[MaximRecoil]

I'm making this thread to describe how I did it, including details that I had trouble finding information about before I started. Hopefully it will help someone else who wants to program their own Protel chassis.

The first thing I did was install DOS 6.22 from floppy disks onto the first PC I ever owned (an Emachines 733i that I bought new in 2001). The floppy drive stopped working correctly many years ago, which is typical, but they are easy to revive. Just remove the top of the drive and clean the two heads with a piece of plain white typing paper soaked with electrical contact cleaner or isopropyl alcohol (fold the paper a few times for rigidity). I've brought all of my floppy drives back to life simply by cleaning the heads (at least 6 of them).

Then I installed ExpressNet version 1.55. For setting up ExpressNet to program my payphone, I followed a video from this site - http://telesfor.org/payphones/doku.php?id=cocot:protel:program#video_manual

I had to rewatch the video a few times, but eventually it made sense. A nice thing about ExpressNet is that, even though it seems convoluted at first, it has a great help menu. Press F1 while most any option is selected and it will bring up detailed information about that particular option.

To create two phone lines for programming the payphone, I bought a Panasonic KX-T61610 off eBay for $35 + $20.55 shipping. It works as-is with its default settings. Just plug your PC's modem (I used a US Robotics 5686 [no letter after the model number, so it's probably an early one] with default DIP switch settings) into one of the Panasonic's extension jacks (I used the second extension jack; it's labeled "12") and plug your payphone into another extension jack (I used the first extension jack; it's labeled "11"), and that's all there is to that. You don't need to connect an outside phone line to it.

Lots of people have said that it's more reliable to have your payphone call your PC than the other way around, but that didn't work for me at all. Even though I heard modem sounds when I tried it that way, both from the modem's speaker and through the payphone's receiver, it never connected no matter how many times I tried. I always got a "time-out on carrier detect" error in ExpressNet. I don't know if it was a problem with my US Robotics modem or what.

At first I couldn't get it to work the other way around either. ExpressNet would try to call from the PC and my payphone would ring, but ExpressNet would hang up after two rings and claim that it got a busy signal. Then I remembered that when I had Payphone.com program my payphone many years ago, they had me do something to the payphone before they called it. So I found those instructions they gave me back then:

1. While phone is hung up, press and hold reset button.
 
2. While still holding program button lift handset.
 
3. Listen for a single beep on the handset, once you hear the beep release button.
 
4. Dial 00 (then your payphone's 10-digit phone number)*
Phone beeps once
 
5. Dial 280 101 0024*
Phone beeps once
 
6. Dial 1861*
Phone beeps once, then hang up

After I did that I did the "manual polling" thing again in ExpressNet to have it call my payphone and it successfully connected and programmed it on the first try.

One more thing: when I created my "site record" in ExpressNet, it wanted my payphone's phone number, and it has to be 10 digits. But my payphone's phone number through the Panasonic 616 was simply "11." So I put in "1111111111" for the phone number, figuring the first two ones would get it through and the Panasonic would just ignore the following eight ones, and that worked fine. I also put in "1111111111" as my payphone's phone number in step #4 of Payphone.com's reset procedure.

[MaximRecoil]

At the suggestion of someone online whose username is 1mrpeter, I tried it at 1200 baud instead of 300 baud and it worked perfectly. He said that a Protel 7000 has to be programmed at 300 baud when using a non-Protel modem, but an 8000 can be programmed at 1200 baud even with a non-Protel modem.

For normal programming (which Protel calls "download parameters") it doesn't really matter whether you use 300 or 1200 baud, because it takes less than a minute even at 300 baud, and it's been perfectly reliable in the dozen or so times I've done it so far (trying out various settings). But for updating the firmware, which is a 64 KB file, 300 baud doesn't cut the mustard. I tried it about 10 times and it errored out on sending block 365 (it takes about 45 minutes to get to block 365) every time except on the last try. On the last try it managed to send all the blocks (460-someodd) but errored out before it could "download parameters," which it's supposed to do after the firmware update if you've selected it on the manual polling page.

Then I reverted back to the stock firmware so that I could try doing the firmware update at 1200 baud, and it worked perfectly. It took about 12 minutes, no errors at all, and then it proceeded to download the parameters (which only takes about 30 seconds), and again, no errors.

I guess I don't need to look for a Protel UPMS1200 modem anymore, since this US Robotics 5686 (no letter after the model number, so I guess it's the first version of it) works fine at 1200 baud with an 8000 chassis.

Also, at first I couldn't get it to even attempt 1200 baud. I thought I'd changed everything from 300 to 1200 baud in the ExpressNet settings (i.e., adding &N2 instead of &N1 to the end of the INIT string and changing 300 to 1200 in modem settings and options & registers), but it still connected to my payphone at 300 baud. As it turns out, I'd forgotten to change 300 to 1200 on the site record page, and it seems that's the setting that really matters. Once I did that it connected at 1200 baud.

Additionally, I learned that there's no chance of "bricking" the payphone chassis by doing a firmware update, because the stock firmware is stored on a socketed EPROM which is read-only (you can only erase it by removing its sticker to reveal its glass "window" and then exposing it to a sufficient amount of ultraviolet light). So doing a firmware update doesn't affect its stock firmware on that EPROM chip at all. Instead, it goes into what Protel calls a "download chip."

After you do a firmware update you can press *#62 on the dial pad and the voice will report the firmware version to you, followed by a "one" or a "two." "One" means that the payphone is using the stock firmware in the EPROM and "two" means it's using updated firmware in the "download chip" (see attached screenshot from the Protel 8000 pocket reference manual). So if all else fails you can disconnect the batteries and phone line from the payphone and it will revert back to its stock firmware in the EPROM.