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Powerbook 100 / 180 : Serial to RS232

Cedsrepairs

Well-known member
Hello

I'm trying to figure out what cable I need to make a serial link between a modern PC/mac and my powerbooks

Let's start with my PB100 : it has avery peculiar serial connector, with only a few pins in it. I'm really not sure what cable to stick in there

The PB180 seems to need a DIN8 connector, there are DIN8 to DB9 adapters out there, but the mac also uses RS422 instead of RS232 which seem to require either special cabling or even adapters.

Does anyone know how to reliably connect a PB100, or PB180, to a modern PC thru serial (rs232) ?
 

Trash80toHP_Mini

NIGHT STALKER
DIN4 is the ADB Port, serial is next to it on the PB100. Mac Serial is RS422, but it's compatible with the lesser RS232 spec.. DIN8<->DE9 (commonly misnamed as DB9) is the short adapter cable I've used for connecting to a standard PC serial cable.
 

Cedsrepairs

Well-known member
Yes, sorry for the newbie mistake I didn't recognize the ADB (mostly because of the weird logo that makes it look like a serial port)

Indeed both the PB100 and PB180 have a similar DB8 that is supposed to be both a printer and modem port

The question remains about the adapters :
RS422 is not using the same logical levels as RS232, in particular it has RX+/RX- and TX+/TX- , RS232 does not work like that at all.

Is it obscure to me what internal cabling these adapters have.
Are they straight, are they crossed, how do they deal with the level problems, etc.
It's likely that there are a variety of such adapters.

I've seen a schematic on the web that says that ground RX+ which "kinda" reverse the polarity of RX- and make it "somewhat compatible with RS232 at low speeds".

There are also proper level adapters (devices) that convert RS422 but that seems overkill for just a quick serial link, it seems to be mostly aimed at industrial equipment.

Or maybe i'm just overthinking this :)
But connecting DB8 RS322 to DB9 RS232 is not as easy as it seems ?
 
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cheesestraws

Well-known member
The stuff you found on the Internet is correct. Just ground the RX+ pin, and it should be fine. That's what all the adapters I have do. No need to muck about with level shifting. An awful lot of peripherals did this too: you can tell that because on, say, the LC, where there was a seperate -5V line from the PSU to driver the differential serial, if that -5 V breaks, then nearly all peripherals still work, which means that the computer isn't doing differential serial to them.

Some premade cables are crossed over, some are not, because of the nightmare of DTE/DCE on the RS232 side. In any case, though, if you want to plug two computers into one another, you'll need a crossed-over cable.
 

Spidey01

Well-known member
My solution was this cable and a copy of SITcom. Worked well enough to getty into my unix machine using one of the generic USB to RS232 dongles we have at work.
 

Cedsrepairs

Well-known member
Interesting ; thanks all

what software did you use on the powerbook side (pb100 in my case ) to do a null modem connection and possibly file transfers ?
 

cheesestraws

Well-known member
Last time I did it, I just used ClarisWorks' "Communications" stuff on the Mac side. Can't remember what I used on the other end; but I think I just used Xmodem to transfer files.
 

Spidey01

Well-known member
On the PowerBook side: Aladdin’s SITcom, which I think is based on Apple’s Communications Toolkit. But fewer floppies and less confusing to install.

On the Linux side: told systemd to run getty on my USB COM port. SITcom can even be setup to robo login without much effort. I assume Debian still has a zmodem package somewhere that could do file transfers but I only wanted a terminal not file transfer.

On the NT side: Tera Term because it’s the only zmodem client I could find for Windows that isn’t 16-bit DOS and doesn’t cost big bucks. SITcom supports others like the older xmodem, but I opted for zmodem as a file transfer protocol between NT and Mac.
 
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