Comms Corner 12 - originally published in the August 1996 issue of PCW Plus.

Following on from last month, HyperTerminal will have opened the new connection and be rearing to go. Other programs may require you to initiate the connection manually. What joy, a live connection that doesn't cost you a penny! Try typing in a few characters at the PC's keyboard. You should see them appear in QTERM's terminal screen on the PCW; a rather unnerving sight, but nevertheless confirmation that everything is working as it should.

You're now in a position to transfer files. If you've got more than one to transfer, Ymodem is the best protocol to use, since this permits the use of wildcards and transmits the file-names as part of the data, saving you from having to type them in individually at both ends. Don't confuse Ymodem with YmodemG, because the latter won't work with a direct link and isn't supported by any PCW software I know of anyway. If you're only transferring a single file, Xmodem is also a viable option, since the amount of extra typing required for one file is minimal. Users of Ron Murray's ZMP program might like to attempt a more efficient Zmodem transfer, although I've had no luck with this protocol on my PCW.

If you use multiple user numbers under CP/M, you need to tell QTERM to look in the correct directory for its files. This is accomplished by typing [PASTE] N, followed by the relevant drive and user number, e.g. A4. If the files you want to transfer are scattered across several directories, you'll have to manually change the user number after each transfer, since QTERM can't cope with multiple directories in one go.

Now type [PASTE] S to send the files. QTERM will respond with the question Mode?. For a Ymodem transfer, type XYK followed by a space and then the file specification. For example, to transfer all program files, you would key in XYK *.COM. If you don't understand the use of wildcards (* and ?), please refer to back issues of PCW Plus or your PCW manual.

For an Xmodem transfer, you can omit the YK from the XYK part. Alternatively, including the K and omitting the Y will give you a protocol known as 1k Xmodem, which also works very quickly but lacks the multiple file facility of Ymodem.

Don't hit [ENTER] on the PCW just yet, or the transfer attempt will time out before you've got the PC ready to receive.

Choose the PC software's Transfer option and select Receive File. You can either use Browse (or equivalent) to select the directory where you want the incoming files to be saved, or type in the path directly. Now select the protocol for receiving the files and you're almost there.

You can now press [ENTER] on the PCW, and follow on by hitting Receive on the PC. If all is well, you should now clearly be able to see evidence of the files whizzing across to the PC. In the specific case of HyperTerminal, a window listing the file currently being transferred will be displayed. The PCW, too, will report the name of the file it is sending, although the cumulative file transfer size seems to be somewhat erratic in QTERM.

Using a Fax Link interface at 38,400 bps, I've been able to sustain transfer rates of 1900 - 2000 cps (characters per second) for prolonged periods, which is probably as good as it gets and certainly more than enough for all but the most gargantuan of transfers. It took me several hours to copy an entire 40 Mb Cirtech GEM hard drive across to the PC, but this kind of thing you only do once anyway, so it's no hardship. It's interesting to note that transferring a few massive files is faster than transferring dozens of minuscule ones, since the PCW has to find and access each file in turn on the disc, which inevitably interrupts the data flow.

If you transfer direct from floppy and experience aborted transfers, which usually manifest with a Error limit exceeded message at both ends, copy the contents of the offending disc onto the M drive and transfer from there instead. The seek time of the drive heads is likely to be just a shade too much for the protocol to reconcile, although I haven't encountered any difficulties in this area.

Transfers from the PC to the PCW require the obvious logical modifications to the above instructions, but are otherwise handled in the same way. Use [PASTE] R in QTERM and Transmit instead of Receive on the PC. Make sure you always start the sender transmitting before you tell the receiver to receive. I don't see why it should make any difference, but I discovered very quickly that it does.

Another trapdoor I discovered is an undocumented limit in QTERM's Ymodem implementation. It appears that QTERM can't transfer more than 64 files in one shot, so bear this in mind when specifying wildcards like *.* on packed discs. If you have many files with almost identical names, you should transfer them by first copying them in batches of 64 to the M drive, from where they can be sent and then deleted in preparation for the next 64. It's a bit longwinded, but the result is the desired one. Of course, the size of your M drive will determine whether the batch size can be the maximum of 64.

You see, there's more to your serial interface than making contact with the outside world. It's admittedly not always the most practical of ways to transfer data between two machines, but if you only need to conduct the odd transfer now and then, it's ideal, since as a comms user, you already own most if not all of the required equipment. It's a lot cheaper than LocoLink, for example, but if you're transferring Loco files, you'll still have the problem of accessing the data on the PC. If this is the case, you'll need to convert your data to ASCII format before transferring it.

Next month, some much needed light relief, as we take a look at the controversial topic of smilies.

© 1997. Page last updated 31st December 1997