Date : Wed, 25 Mar 2009 13:46:24 -0000
From : dominic@... (Dominic Beesley)
Subject: Fwd: BBC B to PC serial cable
-----Original Message-----
From: bbc-micro-bounces+dominic=brahms.demon.co.uk@...
[mailto:bbc-micro-bounces+dominic=brahms.demon.co.uk@...] On
Behalf Of Firth,MJC,Michael,DMJ R
Sent: 25 March 2009 12:34
To: Kish Tailor; BBC mailing list
Subject: Re: [BBC-Micro] Fwd: BBC B to PC serial cable
-----Original Message-----
> From: Kish Tailor <kishtailor@...>
> Date: 24 March 2009 23:21:39 GMT
> To: "MarkWoobster@..." <MarkWoobster@...>
> Subject: Re: [BBC-Micro] BBC B to PC serial cable
>
> I'm on the verge of making this said cable soon. The main problem is
> finding the 5 pin domino din plug for the BBC b micro side. I
> managed to find a seller on eBay that sells them. Then you have to
> choose if you wanna go db 9 or db 25 on the pc side. I plan on
> building my cable with both
> Options and see which works better.
>
> I'm a bit puzzled by this - a PC will either have a 9 way serial port or a
25 way
> serial port (I haven't seen one with a 25 way one for at least 10 years)
which connector
> you need on that end depends entirely on what connector your PC has. There
isn't any point
[snip]
I've still got a few and they do still work nicely as a BBC->Internet
gateway running Linux!
Anyway if you want to go PC->BBC I did a fair bit of experimentation and
came up with the
following, it's a bit long but I think its worth posting to the list just
the once it
can also be found at:
http://www.brahms.demon.co.uk/software/downloads/serial-cable.txt
comments and suggestions welcomed and I'll try and incorporate them in the
guide.
I run about 20m of Cat-5 cable from my office to my cellar running past lots
of very noisy
equipment (I build amateur radio stuff) and the serial cable keeps going no
problems when
the noise becomes far too much for TV reception and working ADSL!
Though this is all catered towards Linux it all works for connecting to a PC
running
other Operating Systems!
(C) Dominic Beesley 2005
see http://www.brahms.demon.co.uk
Connecting a BBC Serial port to Linux
====================================
Here's some notes on connecting a BBC Micro/Master to a Linux box. They are
in no particular order, not definitive, no liability for loss or damage blah
blah. I merely publish in the hope that they may save you some time in the
future.
Also this all assumes a reasonable level of competence in Linux and a fair
knowledge of how to use a BBC. If you're not sure about using the BBC then
there are loads of sources, one of the best being BBC Lives.
http://www.nvg.ntnu.no/bbc/index.php3
Cheers
Dom
Making the cable
===============
This was done using a BBC Master 128 and a custom made cable. There are
various Usenet and website articles discussing how to make up a BBC to
PC/Linux cable, with a lot of semi-religious ranting about the "correct"
way.
The way presented here may not be "correct" but it works for me!
Pin-out RS423
============
(As viewed into back of computer)
B D
> C <
A E
Pin-out RS232 9-pin D
====================
1 2 3 4 5
6 7 8 9
NULL Modem cable
===============
BBC Linux
=== ====
A <- (RX) -----\ +--- 1 <- (CD)
B -> (TX) ------\---|--- 2 <- (RX)
C -- (GND)---\ \--|--- 3 -> (TX)
D <- (CTS)--\ \ +--- 4 -> (DTR)
E -> (RTS)-\ \ \-------- 5 -- (GND)
\ \ 6 <- (DSR)
\ \-------- 7 -> (RTS)
\--------- 8 <- (CTS)
9 <- (RI)
BBC RX (A) -- LIN TX (3)
BBC TX (B) -- LIN RX (2)
BBC GND (C) -- LIN GND (5)
BBC CTS (D) -- LIN RTS (7)
BBC RTS (E) -- LIN CTS (8)
LIN CD (1) -- LIN DTR (4)
Linux Serial Ports
=================
The following assumes you are going to be using /dev/ttyS0 which is COM1 on
a PC based Linux box. If not you should substitute the relevant device
name. Also note that you may find that the various options mentioned below
for handshaking may or may not work.
If you have any supplemental information please get in touch and I'll add it
in below.
On some Linux machines you may find that the serial ports are already set up
to accept connections from terminals in which case you may be able to skip
some of the initial sections.
Terminal software for the BBC
============================
I recommend getting hold of a package called Tequila I got it from:
http://www.nvg.ntnu.no/bbc/software.php3
This needs to be transferred to the BBC by some means though! More on that
later!
Testing your link!
=================
First to try and send a file from the Linux box to the BBC...
On the BBC type in the following program (a basic terminal emulator):
5 MODE 0
10 *FX 203,50,0
20 *FX 7,8
30 *FX 8,8
40 *FX 156,20,227
50 *FX 2,2
70 *FX 229,1
85 OSBYTE=&FFF4
90 REPEAT
100 IF ADVAL(-1)>0 AND ADVAL(-3)>0 THEN PROCout
110 IF ADVAL(-2)>0 THEN PROCin
120 UNTIL INKEY(-33)
125 *FX 2
130 END
1000 DEFPROCout
1010 *FX 2,2
1020 A%=138:X%=2
1030 REPEAT
1035 Y%=GET:CALL OSBYTE
1040 UNTIL ADVAL(-1)=0 OR ADVAL(-3)=0
1050 ENDPROC
1100 DEFPROCin
1110 *FX 2,1
1120 REPEAT
1130 C%=GET
1140 IF C%=10 THEN PRINT ELSE VDU C%
1150 UNTIL ADVAL(-2)=0
1155 *FX 2,2
1160 ENDPROC
A quick explanation of the code...
line 10: sets the receiver to tell Linux to stop sending if there are
less than 50 characters left in the RS423 input buffer.
This
is a bit conservative but its best to be on the safe side at
this point.
line 20: sets the receive speed to 19200
line 30: sets the transmit speed to 19200
line 40: sets the protocol to 8N1 (8bits, no parity, 1 stop)
line 50: enables RS423, selects keyboard as input stream
line 70: disables normal ESCape action, instead ESCape key acts as a
normal key (producing CHR$27)
line 100: if a there are characters in the keyboard input buffer
and there is space left in the RS423 transmit buffer
then call PROCout
line 110: if there are characters in the RS423 receive buffer call
PROCin
line 120: exit if f0 pressed
line 125: disable RS423 make sure keyboard enabled
line 130: STOP!
lines 1000-1050:while there are still keys in the input buffer and room in
the RS423 TX buffer get keys from keyboard (*FX 2,2 selects
keyboard as input stream) and send to printer buffer
OSBYTE 138,2,character
lines 1100-1160:while there are still characters in the RS423 input buffer
read them in (*FX 2,1 selects RS423 for input) and output
to screen (convert char 10 to BBC newline/CR)
SAVE the program and set it of running
If you've got a load of scribble on screen you may already have an agetty
program running on Linux (but its not set to the right speed/parity/stop
bits). You will need to read up on init/agetty/mgetty/mingetty etc to fix
things.
If you get a login prompt then you've got agetty already running on Linux
that is set to the right parameters - woo yay! Though you may also want to
read up on init/getty/agetty/mingetty.
If nothing happens then thats ok! Try sending a file to the BBC:
First we'll set the serial port up using stty (you may need to be root to do
this!). Here the options -clocal says use hardware handshaking - not lo
cal (take note of the RTS/CTS lines), crtscts (use RTS/CTS rather than
DTR/DSR for handshaking - to use them you'll need a different lead!?!?)
stty -F /dev/ttyS0 -clocal crtscts -ispeed 19200 -ospeed 19200
copy <filename> to the serial port
cat <filename> >/dev/ttyS0
if you get garbage double check that the stty settings worked
stty -F /dev/ttyS0 -a
if that still looks ok there is another problem - dunno what!?
try sending some long files and make sure there is no corruption at the BBC
end (especially if you want to transfer files using the simple method shown
below!)
to try sending from BBC to Linux do
cat /dev/ttyS0
and scribble nonsense on the BBC then press RETURN
Logging into linux as a dumb terminal
====================================
- Get to a terminal prompt and log in as root
$ su -
- Start agetty or getty on your linux box - this kills the terminal
# su - -c "agetty -h /dev/ttyS0 19200"
(If you don't have agetty on your system try mgetty, mingetty or uugetty,
but they will probably need other parameters)
with any luck you should get a login prompt on the BBC, from there you can
log in to linux and execute commands, though the formatting codes on linux
will come out as lots of square brackets and numbers. (Linux uses ANSI
codes which the BBC doesn't natively understand).
Type exit to stop the agetty process. If you forget to do this it will stay
running on Linux - re run the BBC terminal program to get at it and do an
exit!
Transferring a file from Linux to BBC
====================================
If you managed to get this far you will probably now want to get a decent
terminal program for the BBC so you can use linux properly. I use tequila
and find it very good!
This consists of two files that need to be transferred to the BEEB. I did
this by writing a disc on a RiscPC but if you don't have one here's another
way which should work...
Download and unzip the tequila files on linux
(http://www.nvg.ntnu.no/bbc/software.php3), there should be three:
ExecMe - this is an unzip utility (when unpacked)
README.txt - read it
TequZip - a zip of the Tequila program.
We need to ge the ExecMe and TequZip files across the serial link to the BBC
and save them on disc.
Type the following program in on the BBC:
5 ON ERROR:PRINT ERL;:REPORT:OSCLI("FX2"):END
10 INPUT "FILENAME"; A$
20 x%=OPENOUTA$
30 *FX 203,50,0
40 *FX 7,8
50 *FX 8,8
60 *FX 156,20,227
70 *FX 2,2
80 OSBYTE=&FFF4
90 REPEAT
100 IF ADVAL(-2)>0 THEN PROCin
110 UNTIL INKEY(-33)
120 *FX 2
130 CLOSE#x%
140 END
150 DEFPROCin
160 *FX 2,1
170 REPEAT
180 C%=GET
190 BPUT#x%,C%
200 UNTIL ADVAL(-2)=0
210 *FX 2,2
220 ENDPROC
And save it.
RUN it and when prompted for a filename enter EXECME
On the Linux machine:
Set the port to 19200 baud with hardware control
stty -F /dev/ttyS0 -clocal crtscts -ispeed 19200 -ospeed 19200
Disable all translation of carriage returns to newlines and vice versa
stty -F /dev/ttyS0 -ocrnl -onlcr -icrnl -inlcr
And send the ExecMe file to the BBC
cat ExecMe >/dev/ttyS0
After the disc activity has all stopped wait 30 seconds then press f0
*INFO EXECME
should give
EXECME WR (01) 00000000 FFFFFFFF 0001726 000?????
======
If the (underlined) length is wrong (especially if it is too short) try
again
and check you typed everything in right.
You should now be able to run execme
*EXEC EXECME
This will produce two files ZipText and Unzip on the disc (if it works - if
not then try re-transferring the file)
Now transfer the TequZip file
LOAD and RUN the transfer program above on the BBC giving TEQUZIP for the
filename
On Linux
cat TequZip >/dev/ttyS0
Again wait for all disc activity to cease and then 30secs after the transfer
and then press f0. (This file will take a few minutes to transfer as the
transfer program is inefficient - in an effort to make it short to type!)
Now on the BBC type:
*UNZIP TEQUZIP
This should unzip the TEQUZIP, if you get messages about BAD CRC then try
retransferring TEQUZIP
You should now have a disc with all the Tequila files on it....
Using Tequila as a Linux Terminal
================================
Using the Tequila program you just transferred you can now connect to Linux
as a fully fledged terminal!
On the BBC type:
*TEQUILA
This should load the Tequila terminal program, (note the title screen has a
10 second delay in it for the unregistered version).
I suggest reading the Tequila help files at this point! But I was impatient
and started in anyway.
Before connecting to Linux we need to set some parameters in Tequila. Using
the menus (navigate using cursor keys and RETURN) if you get stuck try
pressing ESCape to leave a menu, or if you end up in the terminal itself
press SHIFT-f0 to get back to the main menu. Use return to change
configuration
values too.
Using the menus you'll need to set the following: (use cursors/RETURN)
Display
Mode (80 col)
Lines (32)
Cursor (Block)
Auto Linefeed (Off)
Local/Remote Echo (Remote)
Show control Chars (No)
BBC Graphics mode (Off)
Filter (Off)
Terminal Emulation (vt102)
Screen erase type (ansi)
PC characters (off)
Protocol
Baud Rate (19200/19200) (use submenu to set Send/Receive speeds)
Parity (8N1)
Xon/Xoff (Off)
Send Xon/Xoff (No)
Send linefeeds (No)
Echo to remote (No)
Map Delete to CTRL-H (yes)
Local options
Cursor Editing (No)
Cursor Output (ansi)
Press ESCape until you come to a blank screen with a flashing cursor then on
Linux do:
su - -c "agetty -h /dev/ttyS0 19200 vt102"
On the BBC you should now get a login prompt!
You are now connected!
You can execute most Linux commands as normal, no colours though! :p
To finish type exit on the BBC
Automatically starting a terminal
================================
You can add the line:
s0:2345:respawn:/sbin/agetty -h /dev/ttyS0 19200 vt102
to your /etc/inittab file then run
telinit q
This should make the serial line always run agetty.
WARNING: DO NOT do the above if you are not sure that you know how to fix it
if it goes horribly wrong!
Conclusions
==========
I hope the above has been of help in getting you started or may even have
been of use in troubleshooting for other users. Whatever enjoy!
If you have any comments or questions get in touch with me by visiting
http://www.brahms.demon.co.uk
Cheers
dom