Serial port checkout?

Discuss problems with your Micro-KIM here

Serial port checkout?

Postby sr » Jan Wed 23, 2008 11:15 am

I've gotten my Micro-KIM together, built a power supply and hooked the lot up with a case. All that's left before I can start using the thing is getting the serial port up. I'm a bit stuck at this point, and would like to request advice.

With JP[12] (the one for I/O select) open, I have a nice friendly display and keypad access to memory, but with the jumper in the display goes dark. I want to use an old Linux laptop, which is about the only thing in the house that still speaks RS-232, to talk to the uKIM. I've used this Linux laptop to talk to an older, breadboarded project I once built, but this was a few years and several full reloads ago---I'm not even sure which place in /dev is hooked up to the serial port these days! The serial cable is straight-through, and new.

Request assistance. Going out from the uKIM, I've got an untested RS-232 interface; a new, presumed working serial cable; a PC serial port that worked at one time; and only a vague idea of where I should direct my terminal program to talk down the port. Other threads in this forum indicate that either the uKIM or some PC serial ports are not fully compliant, so that in some cases extra hardware trickery is needed. For test equipment, all I've got in this town is a Fluke multimeter, no scope. That's a lot of unknowns. My only clue is the old KIM-1 docs I've looked at, which say that the KIM wants a DEL down its serial port and it will reply with a "kim>" prompt once it's happy. Needless to say, I have not yet established this kind of rapport with the uKIM.

I am a software guy, so methods of troubleshooting that hardware types will find second nature, will require some thinking for me to come up with. I can install kermit (looks like the only serial comm program that made it in the last reload was Minicom) to simplify the me/serial port interface. I might be able to scare up a device that speaks RS-232 down a DB9 and flashes a light when it gets something, to figure out where in /dev I need to direct my talkage. Which should at least answer my questions on the terminal (i.e., PC) side. Other advice? Even if IallITM, I could use a reference to the specific file on the CD.

Thanks in advance! I have been documenting the building, and will post a link to pics once I've tested out the serial.
sr
 
Posts: 8
Joined: Dec Thu 20, 2007 12:49 am

Postby bacon » Jan Thu 24, 2008 4:56 am

If you only have one serial port, it should be /dev/ser0 if I'm not completely mistaken.

You mention an RS-232 interface between the Micro-KIM and the PC. What do you need this for? Or are you reffering to the Micro-KIM's built-in RS-232 interface?

Minicom works fine for me. In fact, it's the only serial terminal on my Linux box that works well for communicating with my Micro-KIM.
bacon
 
Posts: 8
Joined: Aug Mon 06, 2007 3:58 am

Postby RichLeary » Jan Thu 24, 2008 12:49 pm

The Micro-KIM acts like a modem. That means a straight through cable from your Linux machine should work. Set comm rate to 1200 bps and no handshaking to start with. If you can introduce character and line delays do so as suggested in the Micro-KIM manual. With jumper in place do a Micro-KIM reset and then hit return on your keyboard when in the terminal window on Linux that is talking to your device connected to the Micro-KIM. It should work although as noted in a separate thread some PC hardware wants a RS232 signal that actually goes negative. The Micro-KIM signals do not so read that thread for a quick fix.
RichLeary
 
Posts: 5
Joined: Jan Wed 02, 2008 11:12 am

Yes!

Postby sr » Jan Thu 24, 2008 8:17 pm

Thank you for your advice. It seems that I was close, but overestimated the speed at which the uKIM can talk: 9600 is a bit too much. Settings that ended up working:

/dev/ttyS0
1200 8N1
hardware handshaking disabled
software handshaking disabled

I will post a link to pictures soon!
sr
 
Posts: 8
Joined: Dec Thu 20, 2007 12:49 am

Postby vbriel » Jan Fri 25, 2008 8:13 am

I found that sometimes it can't autodectect 9600 but will work if you manually set the baud rate. 4800 appears to be somewhat stable and 1200 is rock steady.

Just like having a real KIM-1.

Vince
User avatar
vbriel
Site Admin
 
Posts: 1184
Joined: Jul Tue 19, 2005 12:10 pm
Location: Ohio

Postby Rich Cini » Oct Sun 25, 2009 9:52 am

All --

Here's how I got it to work. I use Parallax USB->serial adapters for a lot of things with a lot of success but of the problems I have, it's always when "uploading" something to one of my vintage machines. The below worked for me and the MicroKIM but YMMV.

My Hyperterminal configuration is: 1200-8N1, no handshaking. I use the TTY configuration, a 75ms intra-line delay and a 25ms intra-character delay.
Rich
http://www.classiccmp.org/cini/
http://www.classiccmp.org/altair32/
Rich Cini
 
Posts: 6
Joined: Mar Tue 07, 2006 11:27 am
Location: Long Island, NY

Serial port finally working, but ...

Postby thegrendel » Jan Thu 07, 2010 5:57 pm

Well, here's what didn't work for me:

A USB-to-serial port converter. Didn't work under either Linux or Windows.
The converter itself is okay, since it works with other applications.

IBM Thinkpad serial ports for the "newer" models. Anything newer than a 760.
There seems to be a basic hardware incompatibility there. Even doing the suggested -9 V bias didn't help.

---

Here's what did work for me.

An IBM Thinkpad 760XD, circa 1997. I used a straight-through serial cable, one I spliced together myself out of a couple of connectors I had laying around.

It connects fine with minicom, under DSL Linux. But, only 300 baud. 8N1 and 8N2 work equally well. Anything over 300 baud doesn't work, maybe because my cable is so sloppy.

The microcom program sometimes also works. Also DSL Linux, Thinkpad 760XD.
Microcom sometimes works at 1200 baud, but it's inconsistent. Sometimes it doesn't work at any speed. And, microcom is poorly supported and documented.
Minicom seems to work every time at 300, so I'll stick with that.

Weird, isn't it?
thegrendel
 
Posts: 6
Joined: Jan Thu 07, 2010 5:44 pm

Postby thegrendel » Jan Sun 10, 2010 11:52 pm

I've got the serial port working with a Thinkpad 770X, but only under Windows (Win2K,
Hyperterm, 1200 baud, 8N2). It won't work on that machine on the (Puppy) Linux partition, using minicom. Don't know why not.

So, that gives me two options, so far. 1) The TP 760XD, DSL Linux, 300 baud.
2) The TP 770X, Win2K, Hyperterm, 1200 baud.

Interesting.
thegrendel
 
Posts: 6
Joined: Jan Thu 07, 2010 5:44 pm

Postby vbriel » Jan Mon 11, 2010 7:31 am

I can explain why you get different results on 2 different machines. The serial port normally using negative voltage swing but the Micro-KIM only has 5V and ground available, so ground because the source for the swing low. On most machines, this is fine, but on some, it may cause issues.

It might not be a bad idea to post what machines work and what machines have issues with the serial port. As far as the Linux partition, can't answer that one.

Vince
User avatar
vbriel
Site Admin
 
Posts: 1184
Joined: Jul Tue 19, 2005 12:10 pm
Location: Ohio


Return to Troubleshooting

Who is online

Users browsing this forum: No registered users and 1 guest