This graphics command is used to display @ string of characters at a
specified position, angle, slant, colour etc,
This concludes the basic description of the operation of the AVC and
the software commands which are available to make it easy to use.
In the next issue we will describe some applications of the AVC, and
in particular we will introduce the first issue of NAS-CAD —
Simple computer aided design system using the AVC.
2. TECHNICAL TIPS
In this section we are introducing the first instalment of a series
of articles on modifying the NAS-SYS operating system. While the
features which we describe should be useful the intention of the
series is to give sone of the newer Nagcom computer users an insight
into the operating system and its features. The routines described
have generally not’ been optimised for efficiency in respect of
either speed or memory size.
2.1_A buffered keyboard for the Nascom computer
Buffered keyboards allow the user to type in information while the
computer is still performing other tasks. They need to be Used with
care – if you type in answers to anticipated questions, but the
actual questions from the program differ from those expected, the
results can be disconcerting, ta say the least’ Keyboard buffers
usually have a limited ‘type ahead’ capacity – typically 20
characters or less.
The keyboard buffering system which we are going to describe can be
used with any non-networked Nascom 2 or 3 computer fitted with « PIO
land running NAS-SYS 3 or NAS-DOS (and Nascom i computers, with a few
minor changes to the procedure describi All. that is required to
fit it is a short length of wire, a soldering iron and a bit of
software, wo the cost is negligible. A shortcoming, though, is that
the disc user will find the buffering is inoperative while disc
access is in progress. This is because disc access disables the
computers interrupt system, which we use in thie buffering sy!
You will also find that the keyboard repeat speed is less consitent,
and “for games use in articular a type-ahead feature can be
The keyboard buffering can be disabled at any tine by use of the
RESET Key or restarting NAS-8YS (EO). The length of the keyboard
buffer can be changed from within a program by POKing a single
Tocation (down to 1 if required).
The description that follows is intended for those who have some
knowledge of their machine, or who want to know more about it. It
gives all the information you need to implement the keyboard buffer.
In future issues we will give some other technical tips which will
build on the ideas presented
This is an OCR’d version of the scanned page and likely contains recognition errors.