An Overview of Computer-
Program Transfers

by Adam Trionfo


This article was written for OC&GS, Issue #6. That issue was published in 1998; I'm not sure why the article wasn't included. Perhaps we ran out of space, or maybe I felt that it was too esoteric for most readers. Whatever the reason, while this article is now dated and there are simpler ways to transfer programs, this method will still work with materials that many computer collectors may have readily available.

If you have been using computers for a few years, you may have come across, at some point, a serious problem. You have a program on computer A, and you need to use it on computer B -- but they use differently sized disk drives, or maybe the computers use separate file formats altogether. Many people have encountered the common problem of transferring an IBM 5 1/4" disk to another IBM that only has a 3 1/2"-inch drive. This article is about the problems that collectors will encounter in file transfers between different formats, and how those problems might be solved. It is not a step-by-step guide. Rather, it is a generalized approach to these kinds of problems. This information can apply to any computer, be it an Atari, IBM, Apple, Mac or any other.

My first problem-encounter with file exchange occurred when I began using the Atari 8-bits. I wanted to download files from the Web and transfer them to my Atari 800XL. I had no idea how to go about doing this. I had two words in my vocabulary as an overall guide: "null modem." The words were meaningless to me; I didn't have any idea what they meant.

I asked around, and soon learned of an easy way to transfer files: Hook two modems together directly with a phone cord. I did this, and it worked just as promised. Too bad that my Atari modem was only 1,200 baud. That seriously limited the file-transfer speed. It was taking far too long to transfer the files I wanted. I decided to take another look at null-modem transfer.

The idea behind null-modem transfer is simple: Connect two computers directly through two serial cables, and transfer files using a terminal program on each computer. The idea is simple, but it could not be done without a null modem. So what is a null modem? It is a small device that crosses the wires in each serial cable so that the "send" signal from one computer is going into the "receive" pin of the other (and vice versa). That is all a null modem does. If you ever plan to transfer files, it is the best five dollars you can spend. Null modems can be picked up at many electronic stores, including Radio Shack.

So you have a null modem, as well as a serial cable and terminal program for each computer. You are ready if the cables can connect the computers together with nothing in between. When using classic systems, this is not usually the case, as most of them don't contain standard serial ports; you will have to get a hardware device to allow the use of standard serial cables. For example, the solution for my Atari 800XL was an Atari 850 device, which allowed me to use standard, nine-pin serial cables. Once the cables can be connected between the computers, then you are set.

Remember that if you are transferring text files, they will have to be saved as ASCII, so that they can be read in most any text editor or word processor, on any computer. There should be no problem with binary files.

Here is a few simple steps to follow that will allow the transfer of files between computers of different types:

  1. Connect the computers to each other with the cables -- you may need "gender changers."

  2. Make sure that the terminal programs share at least one common file-transfer protocol. Most classic software used XModem, so this may be what you will end up using.

  3. Be aware of the top transfer speed that the older computer is compatible of. For example, an Atari with an 850 device tops out at 9,600 baud. The same Atari with a different device called the PR-Connection tops out at 19,200 baud.

  4. Set both computers to the same transfer speed and terminal emulation. (Although the same emulation is highly recommended, if it isn't possible, for lack of the correct program, you may be able to get by without it -- but the screens may look strange. Don't count on this working!)

  5. Set both terminal programs to the same transfer protocol. If you can, use ZModem or YModem (the latter is sometimes called XModem Batch) to transfer files. If not, use XModem (or Kermit, if you have to).

  6. You will not have to give any AT commands, because you are not using an actual modem. If you type on one computer and press "Enter," the text should appear on the other computer. If this works, then you can start transferring files.

  7. Transfer the files as if you were connected to any BBS. It will work fine.

There is at least one other way to do this that is actually simpler, but has many drawbacks as well. Upload the file you want to transfer to a BBS and then download it to the computer that needs it. This is ideal if you can find a BBS that still allows for 300/1,200/2,400-baud connections. In my experience, many boards will connect at these speeds for an instant, but will then disconnect, as these boards use higher minimum speeds.

With these tips, you will not have to go down the blind path that I did. You will be able to get software from computer A to computer B, and hopefully keep most of your sanity!