VDU for the Amstrad PCW range
----------------------------Yet another terminal program for the Amstrad PCW! The features of this
one
include:
- tty, vt52, control show, and viewdata (Prestel) emulations;
- reliable up to 4800 baud;
- can generate a BREAK signal;
- easy to use!
The viewdata emulation uses double-width characters, and supports all
viewdata
features except for flash and colour (neither of these being supported by
the
PCW hardware!). However parts of the screen which have a non-black
background
are displayed in reverse video.
The program is run by typing:
VDU [TTY | VT52 | CONTROLSHOW | VIEWDATA | PRESTEL] [LOCALECHO]
The optional command line parameters allow you to specify the type of
emulation,
and whether local echo is required, on entry to the program (both
VIEWDATA and
PRESTEL give viewdata emulation). The default is tty emulation and
remote echo.
VDU does not attempt to set up the serial interface, so the Amstrad
utility
SETSIO must be used before running VDU. Examples are
SETSIO R 1200 T 75 B 7 S 1 P EVEN I OFF X OFF H OFF
for contacting Prestel at 1200/75 baud, and
SETSIO 300 B 8 S 1 P NONE I OFF X OFF H OFF
for contacting a bulletin board at 300 baud. Note that Interrupt, Xon
and
Handshake should always be set to OFF when using VDU.
It is possible to set up 'submit' files for running VDU. For example, if
you
regularly contact Prestel over a 1200/75 baud modem you could make a file
PRESTEL.SUB which contains
SETSIO R 1200 T 75 B 7 S 1 P EVEN I OFF X OFF H OFF
VDU VIEWDATA
The following keys have a special effect whilst you are using the
program:
[EXTRA]+1
the
[EXTRA]+2
characters
select 'tty' emulation mode.
All control characters from
remote computer are filtered out, except for ^G (bell), ^H
(backspace), ^J (line feed), ^M (carriage return), and DEL.
select 'vt52' emulation mode. No filtering of incoming
takes place (except for DEL which is replaced by
backspace/space/
backspace), thus the PCW's inbuilt VT52 emulation will be
operative.
[EXTRA]+3 select 'control show' emulation mode. Control characters
received
from the remote computer will be displayed explicitly
rather than
causing the corresponding screen operation (if any) to be
performed. This is useful if you need to determine exactly
what
characters are being sent by the remote computer.
[EXTRA]+4 select 'viewdata' emulation mode. This is required for
services
such as Prestel and Micronet.
[EXTRA]+B
[EXTRA]+D
send a BREAK signal to the remote computer.
toggle local/remote echo. When local echo is selected, all
characters typed are echoed to the screen by the program
(RETURN
is displayed as carriage return followed by line feed).
Remote
echo is used when the remote computer echoes characters
typed.
[EXTRA]+P
emulation
copy the text on the screen to the printer in viewdata
mode.
Graphics characters are replaced by spaces, and
other
characters are not translated thus their appearance will
depend on
the character set of the printer (for example '#' may come
out as
'_').
The output is sent to the logical list device
(LST:), and
can be diverted to a disc file by using the CP/M PUT
utility if
desired. For example, if you type
PUT PRINTER OUTPUT TO FILE LOGFILE
immediately before running VDU, all output sent to the
printer
[EXTRA]+R
emulation
using [EXTRA]+P will be sent to the file LOGFILE instead.
toggle the revealing of hidden information in viewdata
mode.
[EXTRA]+[PTR] produce a dot by dot (graphics) image of the screen on
the
built-in printer (8256/8512 only).
[EXTRA]+/ quit the program.
The ASCII character set (used in the tty, vt52, and control show
emulations)
uses codes from 0-127. Codes 32-126 represent printable characters, and
codes
0-31 and 127 represent control characters (such as carriage return, bell,
etc).
The printable characters correspond to the PCW's inbuilt character set in
that
same range (as shown in Appendix I.4 of the Amstrad CP/M manual). The
full
range of ASCII characters can be typed on the keyboard, for example
[ALT]+A will
give control-A (code 1) and <-DEL will give DEL (code 127).
The differences between the printable characters in the ASCII and
Viewdata
character sets are shown below:
Code |
ASCII
|
Viewdata
|
| Character
Key
| Character
Key
|
-----|----------------------------------|---------------------------------|
35 | hash
#
| pound sign
[SHIFT]+3
|
91 | open square bracket [
| left pointing arrow [
|
92 | backslash
[EXTRA]+1/2 | half
1/2
|
93 | close square bracket ]
| right pointing arrow ]
|
95 | underline
_
| hash
#
|
96 | grave accent
[EXTRA]+8
| wide hyphen
_
|
123 | open curly bracket
{
| one quarter
[ALT]+2
|
124 | vertical bar
[EXTRA]+.
| parallel vert. bars
[EXTRA]+.
|
125 | close curly bracket }
| three quarters
[ALT]+6
|
126 | tilde
[EXTRA]+| divide
[EXTRA]+|
127 | DEL
<-DEL
| small filled box
<-DEL
|
For each code shown, the 'Character' column describes what is displayed
on the
screen, and the 'Key' column shows what you have to type to obtain that
character. VDU performs all the necessary translations for the screen
and
keyboard when viewdata emulation is set. It also produces '*' when you
press
the key marked with the section symbol to make '*#' easy to type, and
produces
the viewdata cursor movement codes when you press the cursor keys to help
when
editing mailboxes. Also, when you enter viewdata emulation, VDU sets a
24 row x
80 column screen viewport. The original viewport is reinstated when you
leave
viewdata emulation or quit the program.
-------------------------------------------------------------Whilst the author retains the copyright of the program and documentation,
they
may be copied and distributed on condition that no charge is made for
them or
any items bundled with them.
Phillip Wade, 219 Marlborough Ave, Chanterlands Ave, Hull, HU5 3LF.
Phone: (0482) 465796 (day), 446196 (evenings).
Academic network email: p.wade@uk.ac.hull.cc.vme
(c) February 1988.