Macintosh 512Ke, MacTerminal and a USB-Serial Adapter

[tevion5]

Recently I have acquired an RS-422 Cable for my very well kitted out Macintosh 512Ke. It already sports an external 800K drive, a HD20, a Midi Interface as well as a LocalTalk interface connected it to my home AppleTalk network with servers hosted on a Classic II and PM 8600.



Seeing as the 512Ke lacks the ram needed to run a lot of interesting networking software, it's use as a terminal is quite intriguing. Perhaps things can be done it for controlling the OS X terminal for example and allow me to administer my MineCraft server from the 512Ke. Or perhaps access a primitive form of E-Mail in text only form? Who knows...

I am studying Computer Science and would love to enable my 512Ke (and my Apple II Plus) to perform some arguably useful tasks in the modern world. I get a great kick out of AppleTalk networking and hosting my 512Ke on the internet through use of my 8600 as an intermediary. Uploading pictures from my iPhone straight onto my HD20 is a blast I can tell you.

So far, all I have been able to achieve is using MacTerminal on my 512Ke to send a series of full stops (.......) over the serial connection to my MacBook Pro running apps like "ZTerm" and "CoolTerm". No matter what setting I use, every character on the 512Ke keyboard results join a "." on my MBP. The 512Ke receives no data from the MBP, communication is one way also.







So, if anybody here can assist me in communicating effectively between my 512Ke and my MacBook Pro via USB-Serial cable I would be most pleased.

(I have also ordered a Raspberry Pi B+ to expand my options with all this vintage network hacking)

I am aware that the images are upside down. That is the fault of vbuletin not my own. You can click them for the proper version.

 

[Anonymous Freak]

When did you move to Australia?

The big thing is to make sure to set the serial port speed on the modern computer to a slow speed - by default it will probably be 115 Kb/s, which is too fast for the 512Ke to handle.

When I did this with my 512K-upgraded original Macintosh, I used 9600 baud.

You also have to make sure to set up the modern computer to allow TTY (serial) terminal connections. I'm at work right now, but I know I have a tutorial bookmarked at home, I'll look it up this evening. (Really early morning your time.)

 

[tevion5]

When did you move to Australia?

The big thing is to make sure to set the serial port speed on the modern computer to a slow speed - by default it will probably be 115 Kb/s, which is too fast for the 512Ke to handle.

When I did this with my 512K-upgraded original Macintosh, I used 9600 baud.

You also have to make sure to set up the modern computer to allow TTY (serial) terminal connections. I'm at work right now, but I know I have a tutorial bookmarked at home, I'll look it up this evening. (Really early morning your time.)

Alas, I've never had this upside-down nonsense with MacRumors from OSX, only from iOS. The plague has spread it seems!

I believe I did ensure the speeds were matching. Both MacTerminal on the 512Ke and SerialTerm on my MPB were set to 9600 baud. I do a good bit of reading on the topic alright, but never enough of course.

Funny enough, on my VERY first attempt, when I would hit a key on the 512Ke, a random character would appear on the MBP. As in if i hit "H", i got "7". If I hit "2", I got "q" and so on....

Then on my second attempt, and since then, I could only get "....." to come up no matter what key I pressed in the 512Ke.

I will double check the TTY field on the MBP next time.

If you could give me a comprehensive guide on this EXACT scenario involving a 512K that would be fantastic! I've been through as much material as i could get my virtual hands on but each site only gives me another small piece of the puzzle. All help is good help and you always know your stuff anon.

 

[Anonymous Freak]

My process was a 512K connected via serial to a physical serial port on a NetBSD server. But seeing as OS X uses the same BSD utilities, it should be the same. And proper USB-to-serial terminals should appear as a /dev/tty<x> device just like a real serial port.

I'll see if I can find the directions I followed when I get home. Worked perfectly the first try.

One difference: I was using MacTerminal, not ZTerm or Coolterm.

 

[Anonymous Freak]

Okay, I'm home.

Unfortunately, the old site I used is gone, and not on the Internet Archive.

http://hints.macworld.com/article.php?story=20030724135653825 has an (old, old, OLD) how-to for it on OS X. Should still work, though, getty is still available in Yosemite, even.

 

[David Schmidt]

Maybe a dumb question, but I can't tell from the picture... is that a printer (null modem) RS-422 cable you have plugged into the USB adapter?

 

[MacTech68]

Are you certain you've checked the start and stop bit, parity and flow control settings?

Also, FWIW, I've used CoolTerm for most of my serial-usb serial comms work.

Scroll down this page to find it:

http://freeware.the-meiers.org/

 

[tevion5]

Maybe a dumb question, but I can't tell from the picture... is that a printer (null modem) RS-422 cable you have plugged into the USB adapter?

The adapter itself (black with translucent cable) is USB to DB9 RS-422.

The Macintosh 512Ke and earlier have two DB9 RS-422 ports for Printer and Modem.

Between the 512Ke and the adapter, is a standard DB9 cable I found around the house. No doubt it was back from the dark, dark Windows 98 days that my house was once part of. I believe it may have once been used to link an old Packard Bell PC with a docking station for my Father's old Palm organiser.

As far as I am aware, a DB9 cable is a DB9 cable. If both devices at either end are RS-422 then the cable transmits RS-422, no?

 

[David Schmidt]

Between the 512Ke and the adapter, is a standard DB9 cable I found around the house.

Danger, danger, Will Robinson! (cue ominous foreboding music)

As far as I am aware, a DB9 cable is a DB9 cable. If both devices at either end are RS-422 then the cable transmits RS-422, no?

Ah - not exactly. RS-422 (and RS-232, which for our purposes is essentially the same) is not a bus - it's a point-to-point connection. Not to mention the various and sundry variations on the theme that a random cable (i.e. the reason for ominous music) might implement. As such, it matters who is sending and who is receiving. The RS-232 spec names these roles as DTE (Data Terminal Equipment) or DCE (Data Communications Equipment). A comms port on a PC or a Mac is a DTE port. The USB to RS-422 device is also a DTE. So somewhere between the two, you need a null modem... otherwise, they will both be transmitting to each other on the same pin, and trying to listen on the same pin. No worky.

If that DB9 cable is a null modem (Apple called these printer cables... has nothing to do with the modem vs. printer icon on the back of the Mac), then you've provided the necessary crossover. Seeing data get transmitted at all suggests you might have the pinout partially right; if they were truly DTE-DTE, you wouldn't see anything at all. But that "random cable" thing could be literally anything at all... and it matters so very much in serial communications.

 

[Anonymous Freak]

Also of note: RS-232 and RS-422 have different pinouts!

The 9-pin D-port on the Mac 128-Plus is *NOT* the same pinout as "modern" DE-9 serial. You will likely need to custom-build an adapter; or find an old "Macintosh modem serial cable" which will be Macintosh-side 9-pin, and device-side 25-pin. Then you'll need a 25-pin to PC-9-pin adapter and null modem.

Here is a page that shows them ("standard PC" is the first one, Macintosh is the third one in the picture at the top.) http://support.shadeblue.com/entrie...-db25-serial-port-pinouts-and-loopback-wiring

 

[tevion5]

Danger, danger, Will Robinson! (cue ominous foreboding music)


Ah - not exactly. RS-422 (and RS-232, which for our purposes is essentially the same) is not a bus - it's a point-to-point connection. Not to mention the various and sundry variations on the theme that a random cable (i.e. the reason for ominous music) might implement. As such, it matters who is sending and who is receiving. The RS-232 spec names these roles as DTE (Data Terminal Equipment) or DCE (Data Communications Equipment). A comms port on a PC or a Mac is a DTE port. The USB to RS-422 device is also a DTE. So somewhere between the two, you need a null modem... otherwise, they will both be transmitting to each other on the same pin, and trying to listen on the same pin. No worky.

If that DB9 cable is a null modem (Apple called these printer cables... has nothing to do with the modem vs. printer icon on the back of the Mac), then you've provided the necessary crossover. Seeing data get transmitted at all suggests you might have the pinout partially right; if they were truly DTE-DTE, you wouldn't see anything at all. But that "random cable" thing could be literally anything at all... and it matters so very much in serial communications.

Ahh! That's actually great news, I might have a simple issue on my hands so. Maybe that cable is some crazy Palm specific pinout or something then...

If so, what intermediary exactly should I get between my USB to RS-422 adapter my RS-422 Port on my 512Ke? A "normal"DB9 cable? Can you point me to one?

Thanks for the info. It seems this sort of thing gets more forgotten about everyday. How will future generations maintain the Apple II's and 128K's when all this knowledge is lost? Anyway, I'm here to learn!

Side note: You say that RS-232 and RS-422 are unimportant differences in my case. How is that so? If I had a USB to RS-232 adapter, would that work with the 512Ke using a standard pinout?

----------

Also of note: RS-232 and RS-422 have different pinouts!

The 9-pin D-port on the Mac 128-Plus is *NOT* the same pinout as "modern" DE-9 serial. You will likely need to custom-build an adapter; or find an old "Macintosh modem serial cable" which will be Macintosh-side 9-pin, and device-side 25-pin. Then you'll need a 25-pin to PC-9-pin adapter and null modem.

Here is a page that shows them ("standard PC" is the first one, Macintosh is the third one in the picture at the top.) http://support.shadeblue.com/entrie...-db25-serial-port-pinouts-and-loopback-wiring

I believe I was aware of this difference and that is why I specifically bought a USB to RS-422 cable instead of a regular RS-232.

Is this not all that is needed?

Or am I missing something entirely?

 

[David Schmidt]

Thanks for the info. It seems this sort of thing gets more forgotten about everyday. How will future generations maintain the Apple II's and 128K's when all this knowledge is lost?

That's why I write and maintain this:
http://adtpro.sourceforge.net/connectionsserial.html
It's a little out of scope for the 512ke - but you need this level of pin-for-pin information, as Anonymous Freak quite correctly points out. Right now, you have an unknown rat's nest of wires, as far as you or we know.

 

[MacTech68]

This all brings back memories of using a serial breakout box with LEDs and jumpers to make serial cable connections in the field before soldering up the final cable. What a hoot!

http://en.wikipedia.org/wiki/Breakout_box