Date : Mon, 16 Mar 2009 15:27:03 +0000
From : me@... (me@...)
Subject: Another set of dumb questions...lol
On 16 Mar 2009, at 15:11, Alex Taylor wrote:
> I think DFS and ADFS explorer will both do this, however I'm too tight
> to pay the shareware fee so I have no experience of using them.
They will. Another option is 65Link:
http://web.inter.nl.net/users/J.Kortink/home/software/65link/index.htm
Here's how to make a cable. Prepare for ASCII art!
~DG
***********************************************************
* HOW TO MAKE A SERIAL CABLE FOR BBC <-> PC FILE TRANSFER *
***********************************************************
Ingredients
==========
- shielded cable with at least four wires; length depending on needs,
up to
many meters
- 5-pin Domino DIN-plug (you might have to shop around for this item;
they're
not that common anymore)
- 9-pin D-type plug or 25-Pin D-type plug, depending on your PC's serial
port(s)
Recipe
=====
Make the following connections:
Pin Pin
(9 P) (25 P) PC BBC Pin
----- ------ -- --- ---
5 7 0V (Ground) Gnd (Ground) 1
2 3 RxD (Data in) -------------- TD (Data out) 2
3 2 TxD (Data out) -------------- RD (Data in) 3
1 8 DCD ---+---------- RTS 5
6 6 DSR ---+
4 20 DTR -------------- CTS 4
7 4 RTS ---+
8 5 CTS ---+
(The +'s mean that locally on the PC DSR has to be connected to DCD
and that
RTS has to be connected to CTS.)
Pin numbering
PC: BBC:
9-pin D-type or: 25-pin D-type 5-pin Domino DIN-plug
(male)
_____________ _______________________ _____
\ 1 2 3 4 5 / \ 1 2 . . . . 13 / / \
\ 6 7 8 9 / \ 14 15 . . . 25 / / 5 3 \
--------- ------------------- | 1 |
\ 4 2 /
\ /
-----
The views of these figures are all from the outside (the backs of the
computers) into the sockets, i.e. they show the wiring sides of the
plugs.
Some tips
========
If you plan to wire up your BBC to a PC, you might learn from what I
have done wrong:
- You can insert the BBC-plug into the RS423 port in two ways. Do it
the right way! (A handy tip I received is to put some Tippex on the
top of the plug.)
- Find out which PC's RS232 port is COM1 and which one is COM2. I
thought
COM1 is always the 9-pin socket and COM2 always the 25-pin socket,
but
on the PC I used it was exactly the other way round! (Btw. Does
anyone
know of an easy way to find this out?)
# The Theory
# =========
#
# It will be clear that the Beeb's Data-In has to be connected to the
# PC's Data-Out and vice versa.
#
# It is more complex with the other connections. These are meant for the
# hand-shaking between the Beeb and the PC. This basically means that
the
# Beeb and the PC can tell each other when they are ready to send/
receive
# data. A handshaking mechanism prevents one of the computers to send,
# when the other one isn't ready to receive, in which case data would
get lost.
#
# The reason for the unclarity of the handshaking pins, and also the
reason
# why there appeared to be two "schools" of people on how to connect a
Beeb
# and a PC during a recent discussion on the BBC-mailing list, is two-
fold:
#
# - the RS423 and the RS232 are only *interfaces*. An
# interface definition only defines the *local* aspects of an
# interconnection between the computers and not the *remote* aspects.
# (Both the local and remote aspects together form the communication
# *protocol*, which is the important thing in our case. For a good
# treatise on interfaces and protocols read "The design of Telematics
# Systems" by C. Vissers who is my PhD supervisor :)
# - the RS232 interface definition (CCITT V.40 or V.42, I believe) is
just
# plain bad (its definitions of the functions of the pins are
ambiguous).
#
# If the above sounds a bit too theoretical to you: the problem is that
# you have a lot of freedom in connecting the pins, depending on the
# communication protocol you use.
#
# On the Beeb the above is not much a problem, because the RS423 is very
# simple: if the Beeb wants to send it raises its RTS signal and waits
# until its CTS signal is raised by the other computer; for receiving
it's
# the other way round.
#
# However, the RS232 of a PC is more complex. Its definition suggests
(but
# not necessarily prescribes) that the DTR pin has a function similar to
# the Beeb's RTS pin and the DSR pin a function similar to the Beeb's
CTS
# pin. Most protocols implemented on the PC (and all I tried) adhere to
# this. This is why you have to connect the Beeb's RTS to the PC's DSR
and
# the Beeb's CTS to the PC's DSR.
#
# But things are more complex. The RS232 also has a DCD (data carrier
# detect) pin, which can be used to detect if there is a device
connected
# to it. Most (but not all) protocols implemented on a PC use this. As
# the Beeb has no complementary signal, a "circumvention" is needed. The
# easiest way to circumvent this is to connect this pin to the PC's DSR
# pin, so that every time it receives a DSR-signal, the PC automatically
# knows there is also a device connected.
#
# To make things even more complex, the RS232 also has an RTS and a CTS
# pin, albeit with different functions than on a Beeb. Some protocols
# implemented on the PC use these for a second handshake after the
# handshake with DTR/DSR/DCD. (Don't ask me what it is good for.) The
# easiest way to circumvent this, is to connect the PC's RTS pin simply
# to its own CTS pin.
#
# If you want to experiment with the different types of handshaking
# described above: it is easy to do so with QBASIC (included in MS-DOS
# versions 5 to 6.20, I think). Look at the help item for "OPEN COM".
#
#
# To conclude
# ==========
#
# - The wiring required for the handshake depends on the protocol you
use.
# - Nearly all protocols implemented on the PC treat the DTR pin as the
# Beeb's RTS pin and the PC's DSR pin as the Beeb's CTS pin; so you
need
# to cross-wire these.
# (To the people who think RTS/CTS should be cross-wired on both
computers:
# I'm not saying you were wrong or that your suggestion will never
work;
# however, if it works for you you're using a pretty esoteric protocol
# and it will probably not work with most other protocols.)
# - Many protocols implemented on the PC also wait for a DCD signal
during
# handshake; therefore it's useful to connect DCD to DSR on the PC.
# - Some protocols use a second hand-shake. In order to "circumvent"
this,
# connect the PC's RTS pin to its CTS pin.