20.004 How do I transfer files between computers using NULL modem?
Description
This article is from the Apple II Csa2 FAQ, by Jeff Hurlburt with numerous contributions by others.
20.004 How do I transfer files between computers using NULL modem?
You will need a NULL modem connector and each computer needs a modem cable
and telecom program. A IIe or II+ will also need a serial card.
____________ ____________
| PC or Mac | | Apple II |
| running a | | running a |
| telecom | <--modem--> [NULL modem] <--modem--> | telecom |
| program | cable [connector ] cable | program |
|____________| |____________|
"NULL modem" means "no modem". A NULL modem connector is just a pair of
connectors wired 'back to back' with a few lines switched so that each computer
views the other pretty much as though it were a modem. Radio Shack, Marlin P.
Jones, and other places sell NULL modem adaptors in the form of small modules
or short cables for a few dollars; or, you can make your own.
Since a NULL a modem connection generally requires fewer control signals
than a connection to a real modem, there are many workable variations of this
setup. One pretty good try is to use a serial printer cable connected to the
Apple II-- for example, on a IIgs you can use a Mac Imagewriter I cable. This
eliminates the need for a NULL modem adaptor. (You will probably need a Female-
Female plug adaptor to connect to the PC* COM port or PC modem cable.)
____________ ____________
| PC or Mac | | Apple II |
| running a | * | running a |
| telecom | <--[Fem-Fem]--><--NULL modem--> | telecom |
| program | [adaptor] cable | program |
|____________| |____________|
One possible disadvantage of this method is that signal lines may be missing
and you will not be able to get hardware handshaking. (Tests using the IW-
I cable on a IIgs showed no loss of speed under Spectrum or ADTgs.)
On the Apple II side, you can choose from several good telecom programs.
Since you would like to be able to do Z-modem transfers, good choices include
Intrec's ProTerm-A2 3.1 (Enhanced IIe -- IIgs), MGR Software's Modem MGR (II+ -
- IIgs), AnsiTerm (IIgs), and Spectrum (IIgs). You can also choose from among
many other programs. Generally, these support X-modem but do not support Z-
modem.
If you're running under a current version of Windows, HyperTerm works very
nicely on the PC side. (For sending Text files from PC to Apple under HT, be
sure to uncheck "send line enders" in the ASCII settings.) If there is a
choice of terminal emulations, it seems best to stick with something simple,
such as "ANSI" or, even "none", or, if available, "auto-detect". (For transfers
to an Apple II running ZLink, select "Auto-detect" in Hyperterm.)
A good NULL modemming program for running under DOS is Telemate, commonly
available as shareware. Many other telecom programs are available and work fine
under current Windows, old Windows, and DOS. Similarly, there is a good
selection of Mac telecom wares.
To do transfers, you just connect the modem cable from each machine to the
NULL modem connector. If your PC or Mac has a spare COM port, the connection
can remain in place without disrupting normal net connections through the other
COM port.
[Modem to net]
|
modem cable
COM1
____ |______ ____________
| PC or Mac | | Apple II |
| running a | COM2 | running a |
| telecom | <--modem--> [NULL modem] <--modem--> | telecom |
| program | cable [connector ] cable | program |
|____________| |____________|
If you can not use a separate PC or Mac port for your connection to the
Apple II, you can move the PC modem cable connection from your net modem to the
NULL modem for doing transfers or use a switch box.
For a GS, the recommended modem cable is a "high speed" type which allows
hardware handshaking and, if present, this option should be set in the GS
telecom software. The same is true for other Apple II's with serial ports or
boards (like the Super Serial Card) which can do hardware handshaking.
However, a "plain" modem cable-- one supposedly without lines for hardware
flow control-- usually works fine. (Often, the main limiting factor will be
your serial card or serial port hardware and the speed of your Apple II. Apple
II's with accelerator cards or chips can usually achieve better transfer rates
than unaccelerated machines.)
Set the same format (8-N-1), baud rate, and protocol (e.g. Z-modem) on
each telecom program.
Note: "8-N-1" means 8 data bits, No parity, 1 Stop bit. Today, most ports and
cables will support hardware handshaking; so, this should be the usual flow
control setting. (If it does not work, check your cable to see that connections
match those suggested for your Apple II and interface. If you can not get
hardware handshaking to work, then you may need to specify a non- hardware flow
control option for one or both of the connected computers .)
A good first-try speed setting seems to be 9600 baud. If you get errors,
try moving down to 2400 baud (or, in at least one reported instance, moving up
to 19,200). An accelerated GS running Spectrum can connect with modern PC's
running HyperTerm at 57.6k baud or better. An unaccelerated GS will top out
around 38.4k baud.
Note: Spectrum, ProTerm 3.1, Modem MGR, and some other newer Apple II telecom
programs do not require that you modify IIgs Control Panel settings for speed
and handshaking. Since Spectrum directly accesses the GS serial port, speed,
etc. settings are done in the program. (By the way, this frees-up Slot 2 -- the
GS modem firmware Slot-- for any peripheral card which needs to have its Slot
set to "Your Card" in the Control Panel.)
Note: On the PC, HyperTerm allows setting the Port Configuration-- i.e. Format,
Baud Rate, and Flow Control for COM1 or COM2-- for a particular setup which you
can save under a name, like "GSxfers.ht". Whenever you start HyperTerm to do
transfers to/from the GS, you need to Open GSxfers.ht (or whatever you name it)
in order have your setup in place.
Place each program in terminal mode-- often, this is the default mode. Or,
the particular telecom program may have menu items or buttons you select for
specific kinds of transfers.
Next, you will usually select the function (send or receive) on each
machine and the protocol. The protocol should be the same on both machines. Z-
modem is the best choice for most single or multiple file transfers. (Text
files can be an exception-- see the next question. A plain ASCII transfer will
circumvent most problems but is slower; and, you may need to send and receive/
capture files one-by-one instead of in batches.)
Finally, you will select the file or files to send or "Open".
At the start, some experimentation is likely to be involved in getting
your computer-to-computer transfers going. For example, you may find that it
matters which end you start first. (When using ZLink on the Apple II and doing
an X-modem transfer, start the Send side first, then the Receive side.) If your
setup works best starting Receive first, you may find that one telecom program
or the other does not give you enough time to start Send-- i.e. it keeps
"timing out". The fix is to change the program'
s "Time Out", "Inactivity Delay", etc. setting.
Note: Some telecom programs may expect an end-of-send signal which the sending
program does not supply. Pressing CTRL-X or RETURN on the Apple II or ESC on
the PC often seems to work okay for terminating the Send.
----------------------------
By: Jeff Blakeney
You don't need to manually tell Spectrum or other modern telecom programs
to receive a file each time you do a Z-modem transfer. Just make sure that you
have Auto Receives turned ON. In Spectrum the setting is in the Settings/File
Transfer/Receive Options... dialog.
By: Rubywand
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