Path: news.weeg.uiowa.edu!news.uiowa.edu!hobbes.physics.uiowa.edu!math.ohio-state.edu!wupost!waikato.ac.nz!comp.vuw.ac.nz!actrix.gen.nz!dempson Newsgroups: comp.sys.apple2.comm Subject: Re: Null Modem Transfers Message-ID: <1993Jul21.072912.24984@actrix.gen.nz> From: dempson@swell.actrix.gen.nz (David Empson) Date: Wed, 21 Jul 1993 07:29:12 GMT Sender: dempson@actrix.gen.nz (David Empson) References: Organization: Actrix Information Exchange Lines: 100 In article detrolio@andromeda.rutgers.edu (David De Trolio) writes: > I have an Apple IIc with a few years of valuable work on disk. > > I would like to transfer some of the text files in ASCII mode to > my PC, but am at a loss has to how, what this "null modem" is, etc. A "null modem" is simply a serial cable in which several pairs of signals have been swapped. See below for a more involved description. There is a commercial solution to all of this: a program called "CrossWorks", which includes all the necessary cables and software. If you want to do it yourself: For the IIc, you'll need a cable which connects the IIc to a serial printer with a DB-25 connector (such as the ImageWriter I or various Epson-compatible printers with a serial port option). You will also need a "gender changer", which is a small device with a female DB-25 connector at both sides, with all signals connected straight through. The cable goes from the IIc's serial port (either will do, but most software will use the modem port), is plugged into the gender changer, and then the other side of the gender changer goes into the PC. If your PC has a 9-pin serial port, you'll also need the approprate "9-pin to 25-pin" adaptor, which should be available in any PC hardware shop. Now you just need communications software on each computer, which is able to send and receive files using some kind of protocol (such as XModem or YModem), and transfer the appropriate files across to the PC. This will only work for transferring text files, and you'll need to "fix" the text files when they get to the PC. The Apple II and PC use different ways to mark the end of a line in a text file: Apples use a Carriage Return, but PCs use Carriage Return and Line Feed. There are probably a lot of programs which can do this conversion (it may be easier to find one for the IIc, in which case you would convert the files before sending them to the PC). If you want to transfer any other type of file, you may need to translate the data in some way. For example, AppleWorks files cannot be used by PC programs (except for SuperWorks, the AppleWorks clone), so you would have to translate them into a form which the PC program can deal with. At the simplest level, you could use AppleWorks to convert the files to text, and recreate the file on the other side. This will lose all Word Processor formatting, all Database reports, and all Spreadsheet formulas. There is no easy solution to this, short of CrossWorks, or possibly using a Macintosh to translate the files into another form which the PC can deal with. You cannot transfer any _programs_ to the PC - they will not work! The following is a more detailed description of a "null modem" cable. Skip this if you don't want to read anything too technical. In a "standard" RS-232 serial cable with DB-25 connectors at each end, all the desired signals are connected straight through - you can use a 25-way ribbon cable. This sort of cable is used between a "communication" device (such as a modem) and a "terminal" device (such as a terminal or printer). The two types of device have different serial connector pinouts. A computer might be a "terminal" or "communications" device - it depends on the computer. For example, the IBM PC is a "terminal", and the Apple II Super Serial Card can be configured as either. A "null modem" cable lets you connect two "terminal" devices (or two "communications" devices) directly to each other. The simplest such cable has the transmit and receive data lines swapped over, so that one computer's transmit data pin is connected to the other's receive data pin. It is also common to swap over the flow control signals (DTR/DSR and RTS/CTS, for example). None of the above has anything to do with the "sex" of the connector - most devices use a female DB-25, but some (such as the PC) use a male DB-25. You simply need a "gender changer" to deal with these. When dealing with non-standard serial ports (such as the IIc), you can usually get a cable which allows you to connect the computer to a standard device (with a DB-25 serial port). This cable can be chosen to connect to a "communications" device or to a "terminal" device. In the case of the IIc, this would correspond to a "IIc Modem Cable" and "IIc Printer Cable" (for an ImageWriter I, Epson-type serial printer, etc.) -- David Empson dempson@swell.actrix.gen.nz Snail mail: P.O. Box 27-103, Wellington, New Zealand