Give your printer more brains than it was born with
THE Watford Printer Monitor ROM is a very interesting new product
which positively reeks of Cambridge knowledge engineering.
The BBC MOS - Magnificent Operating System - makes provision
for a printer driver routine to be attached to the MOS to which
all characters intended for a printer will be sent.
This is to allow printers which either do not conform to the
Centronics or RS432 interface standards to be attached to the
BBC Micro. Or, as in this instance, to give the printer more intelligence
than it was born with.
The monitor performs three functions:
1. It can be set up to print with a left margin and top and
bottom margins and to provide form feed and other paper feeding
commands on printers which do not have these functions built in.
2. It will replace multiple, forgettable control codes for the
printer's functions by single codes.
3. It will print user defined characters - provided the printer
has a graphics mode which can be switched on and off in the middle
of a line.
The ROM is supplied with a 50 page manual and a function key
strip for your printer. The function keys are used to provide
manual access to a range of printer functions - form feed, line
feed, setting margins, selecting a character set and so on.
The manual is written at a high level and clearly the author
is an expert on the BBC MOS.
However, fascinating though the technical notes are, the non-expert
user, and even some who have been publicly exhibited as experts,
find it hard going.
It needs quite a lot of digging to get things to work. Using
the codes to turn on and off the various printer fonts is quite
easy but when it gets on to setting margins it is difficult to
find out how it should be done.
Setting up the monitor is however, quite easy. It needs the
following commands:
• *PRAM1 or <1><D><D BREAK>
to allocate workspace. When using a word processor it is best
to choose the private workspace option as it is usually not clear
what part of memory which may be free under Basic will also be
free under the word processor.
• *PRINTER <printer code> to select the required
set of printer functions.
• *PAPER66 or *PAPER72 or *PAPERCON to
choose a form length and top and bottom margins. The latter is
for use with word processors and stops the Printer ROM interfering
with the word processor's page layout.
• *MARGIN hh to select a left margin - 0 to be selected
when using a word processor.
Using *HELP STATUS will now show that everything is in
order. It will say:
1 private page
PMON parallel printer selected.
"1 private page" means that the machine operating
system has given it a page of memory which, if the other ROMs
are well behaved, will be kept for the printer ROM's use.
"PMON parallel printer selected" means that the printer
is being assumed to be connected to the Centronics interface.
If this is not so then issuing the command *FX5,6 will select
the serial (RS423 or RS232C) output routines.
The printer monitor is now in control of the printer and every
character sent to the printer - selected as usual by VDU 2 or
CTRL-B - will pass through the monitor and be checked for job
codes.
These are character codes which are not printed as characters
but interpreted by the printer monitor as a command.
The job codes are detailed in the appendix corresponding to
the printer type selected.
For instance, to use an Epson FX-80 appendix 6, for printer
type EPb, gives an introductory discussion of what the printer
monitor does and what is left to the printer's own functions,
followed by a list of the character codes sent to the printer
which are intercepted and interpreted by the monitor.
Without the printer monitor to start printing in italics you
would have to send ??? and, what is worse, find it in the manual.
With the printer monitor you simply send code 184 and return
to the normal font with the code 168.
The ROM recognises nine printers — Seikosha GP100, Tandy LPVII,
DMP100 and DMP200, NEC PC8023 and Epson FX, RX and MX printers.
It will also work with the Seikosha GP80 and Tandy DMP120 but
these do not support some of the functions of their more expensive
or newer brethren, so the full range provided with the ROM cannot
be used.
As has been mentioned before, it can be used with word processors.
Unfortunately, although it can be used with Wordwise (using the
Output Control code command) it cannot be used with View (with
the Highlight commands).
It also seems unlikely that it can be used with Merlin Scribe
as only printer codes in the range 0 to 31 can be embedded in
Merlin Scribe text.
It is an excellent program though the manual could do with more
examples and explanation for the novice user. Even so, to avoid
looking up the codes in your printer manual and to be able to
print user defined characters this ROM is worth buying.
C.W. Martin
• Since this review was written Watford have announced that
a more user friendly version of the manual is shortly to appear.
The original manual was only a temporary version.
