Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!usc!jarthur!nntp-server.caltech.edu!madler From: madler@nntp-server.caltech.edu (Mark Adler) Newsgroups: comp.sys.handhelds Subject: Re: mac cable to 48sx, using MacKermit Message-ID: <1991Mar28.172709.18601@nntp-server.caltech.edu> Date: 28 Mar 91 17:27:09 GMT References: <1991Mar28.144445.24501@bigsur.uucp> Organization: California Institute of Technology, Pasadena Lines: 70 Don't worry about the shield line at all. In case you're not sure if you know which end signal ground is really on, you can connect shield to signal ground. If you are sure, just leave it unconnected. It looks like you have it right, if you're diagram is the perspective I think it is (you might specifiy "looking at the connector on the Mac" or "looking at the plug"--you could also avoid ambiguity by offsetting the pins, as they are in the real connector). Here's some diagrams out of the HP documentation: 2.1 Cable Wiring The pin definitions for the HP 82208A (IBM) and 82209A (Macintosh) serial cables for the HP 48 are shown on the next page, including the 25 pin end of the 9-25 pin adapter. All signals are labeled from the HP 48's point of view. HP 48 I/O Cable Pinouts ______________ Macintosh end of cable | - - - | 5 -- RX (input)---|--V V-------| 4 -- Signal GND | - - - | | ^-|--3 TX (output) \ - - / ----______---- PC end of cable with 9-25 adapter /------------------7 Signal GND | /----------3 TX (output) | | /--------2 RX (input) 13 V V V V------1 SHIELD ___________________________ \ O O O O O O O O O O O O O / \ O O O O O O O O O O O O / ----------------------- 25 14 PC end of cable /--------------5 Signal GND | /----------3 RX (input) | | /--------2 TX (output) V V V 1 _____________ \ O O O O O / \ O O O O / ------- 9 6 Notes: 1. Output = from HP 48 _________ s. Input = to HP48 | o o o o | \_______/ ^ ^ ^ ^ | | | \------ 1 SHIELD | | \---------2 TX (output) | \-----------3 RX (input) \-------------4 Signal GND Also, if it doesn't work, you can always try simply reversing the transmit and receive lines. RS-232 is spec'ed so that that can't hurt anything. Mark Adler madler@pooh.caltech.edu