Archive Magazine 1996/ARCHIVE_96.iso/text/specials/a4

Text File | 1996-09-02 | 33KB | 736 lines

                Acornæs New Portable Computer
                -----------------------------

Paul Beverley

In mid-June, Adrian and I took a trip down to Acornæs Fulbourn Road
factory where we were able to öget our hands onò one of Acornæs new
portable computers. Iæm sure you have lots of questions about it, so
Iæll see if I can answer them. I will start with some factual
information including Acornæs own spec sheet and then give some more
subjective views of what we think of the new machine and its future.

    The name  ----  The name of the new computer is the öA4ò.

    The size  ----  The size of the new computer is also A4!

Lay a sheet of A4 paper on the desk and that is the footprint of the new
A4 computer. As you can see from the pictures on this page, Acorn have
gone for a fairly conventional layout with the LCD screen (no, sorry,
itæs mono, not colour) on the underside of a flip-up lid revealing an
83-key UK PC keyboard.

        The basic specification

The A4 is in no sense a cut-down machine. It runs on a 24MHz ARM3 and
has 2 or 4M of RAM running at 12MHz; RISC-OS 3 is in a 2M ROM and the
display is VGA Ö 640 ╫ 480. The hard drive is a 60M 2╜" IDE and the
floppy drive is 2M, as per the A5000, so it will handle all the Acorn
formats plus the MS-DOS formats up to 1.44M.

In other words, in terms of processing power, this is an A5000 in a
notebook case! It even has a bigger hard drive than the A5000 Ö 60M
instead of 40M.

        The price

The basic configuration (model I) with 2M and no hard drive is ú1399
+VAT (ú1644) and the model II with 4M and a 60M hard drive is ú1699 +VAT
(ú1996). The education prices are ú1099 +VAT and ú1399 +VAT
respectively. The price includes a mouse and a mains operated
battery-charger.

        The weight

The A4 with 60M hard drive and including the battery pack, weighs almost
exactly 3kg.

        The wait (!)

How long will you have to wait to get hold of one of these new
computers? Well, official Acorn sources say that they will be going into
full-scale production in September. Basically, there will be just about
a couple of hundred made over the next month or so and then the full
scale production will start in September. What it boils down to is, if
you want one, send a cheque into us a.s.a.p. and we will service orders
in strict rotation as we get stocks.

        The screen

The display is produced on an LCD screen 182mm ╫ 137mm consisting of 640
╫ 480 cells. This is a so-called 9" screen, i.e. 9" across the diagonal,
compared with the standard Acorn 14" monitors which are more like 13"
across the diagonal. (The tube is 14" diagonally but only 13" is used
for the display.)

The standard screen mode for the A4 is mode 27, the 16 colour VGA mode.
It is possible to display other modes but the low resolution modes like
12 and 15 come out as a half-height screen which is quite difficult to
read.

The technology used for the screen is ötwin layer Formulated Twisted
Nematicò. (No, it doesnæt mean anything to me either!) What Acorn have
done is to write a special 15-grey-scale driver for the screen to get
the best effect of displaying a colour signal on a monochrome screen.
You may wonder why it is 15 and not 16 grey levels. This is explained in
a technical note at the end of this article but it is to do with the
fact that the grey scales are obtained on what is basically an on/off
matrix of pixels, by switching each pixel on and off all the time. It
leaves each pixel on for a greater or lesser proportion of the time in
order to give the effect of various shades of grey.

For those of you not familiar with LCD screens, it is worth pointing out
the limitation of this kind of display. First of all, you will find them
difficult to use where there is a high level of ambient lighting. The
display is artificially lit with fluorescent edge-lights. The brightness
of this lighting can be adjusted but, even at maximum brightness, as the
ambient light level rises, the display becomes less clearly visible
because of the lack of contrast.

The other limitation is that there is a slight time delay as the display
changes. This means that moving objects leave a track across the screen
Ö only for a fraction of a second, but it can render some software
(especially games!) unuseable on an LCD screen. The A4 has a standard
video output as well, so if your portable is to be used between, say,
two different sites and you can afford to have a conventional monitor
available at each, you can avoid the problems of having to use an LCD
screen.

To illustrate the limitation of the LCD screen, when we first sat in
front of the A4, we couldnæt find the pointer on the screen. How do you
find the pointer normally? Well, what I do is to wiggle the mouse about
and look for a moving object on the screen. If you try that on the A4,
you will never find the pointer! The only way to find it is to move it
hard over to the left of the screen and leave it stationary and look up
and down the edge of the screen until you find it. (An Acorn spokesman
said that, on the production machines, there would be a re-defined mouse
pointer which would be more easily visible.)

        Connectivity

Working round the edges of the computer, on the front is an on-off
(rocker) switch and an LCD display of the battery state showing 20, 40,
60, 80 and 100% charge.

Along the right hand edge is the floppy drive and, underneath a
flip-down cover, a headphone socket, a socket for an external AT-type
keyboard (see under Comments below), a mouse socket and an RS232 serial
port. Apart from the external keyboard socket, these are functionally
identical to those on the A5000.

Along the back of the case, again hidden behind a flip-down cover, are a
standard bi-directional Centronics parallel printer port, a battery
charger input socket (9-pin D-type socket) and an external monitor
socket (15-pin D-type socket). There is also a reset switch on this back
panel.

The fourth side is where the battery pack slides out and it has a
removable cover where an Econet upgrade can be fitted. This is not the
standard Econet circuit board as used on all Acorn machines since the
Master 128. There is nowhere near enough room for a circuit board of
that size!

The only other controls are on the underside of the lid alongside the
LCD display. There are controls for the brightness and contrast of the
display Ö brightness being the strength of the side-lighting of the
screen Ö and five LEDs which are actually duplicated on the top of the
lid so that they can be seen even if the lid is down. The five LEDs are
power ON/OFF, battery state (see below), battery charger status and
activity light for the floppy and hard drives.

        The battery and charger system

The battery lasts between about 2╜ and 3╜ hours depending on how much
use you make of the hard drive and how high you have the side-lighting
on the LCD screen. Charging takes about 7 hours from empty to full. You
can get a spare / replacement battery pack for ú50 +VAT. The battery
packs have a finite life, said to be around 1,000 complete
discharge/recharge cycles.

The A4 has a sophisticated system for reducing power consumption. First
of all, there are obvious things like automatically switching off the
hard drive when not in use. This can be set to happen after 1, 2 or 5
minutes of non-use. (You can also force the drive to spin down by using
a keyboard short-cut.) The LCD screen switches off after a period of
non-use and there is also a mechanical switch which operates when the
lid is closed.

The more sophisticated system is the dynamic power management. What
happens is that, as long as the computer is doing something active, the
processor and memory operate at the full 24MHz and 12MHz. However, as
soon as the computer idles Ö even for, literally, a fraction of a second
Ö the speeds are dropped to 6 and 3MHz respectively, thus saving more
power.

If you want to keep track of the amount of power remaining in the
batteries, there are several ways. We have already mentioned the LCD
display on the outside of the case showing 20% charge bands. Then there
is the LED indicator referred to above. If it is green, it means it is
on trickle charge, amber means it is on quick charge, flashing green
means you have some sort of fault, flashing red means the battery is
getting low and blinking red means that the computer has been forced to
shut down!

The computer is quite intelligent about shutting down. If the battery is
getting low, it suggests, quite politely, that you ought to shut down or
plug in the power connector. If you ignore that warning (which is
difficult because the LED flashes, the screen flashes on and off and the
loudspeaker gives a double-bleep) it will, after a few minutes, shut
down automatically with the loss of any un-saved files. Some
applications, however, have been set up to take this eventuality into
account by providing an auto-save facility. When you subsequently start
up the system, a dialogue box will alert you to the fact that it has
previously been shut down because of battery discharge, so you can then
go and see whether your file(s) have been saved successfully.

        The mouse

The mouse supplied with the A4 is a Logitech mouse, as are the ones
supplied with current machines, but it is a new design. It is,
apparently, a ösculptured mouseò. In other words, instead of being
angular like the existing Logitech mice (which are shaped vaguely like a
segment of cheese, come to think of it!) it is rounded to fit into the
palm of the hand.

        The keyboard

If Acorn have reduced the keyboard from 103 to 83 keys, does that mean a
reduced functionality? Actually, in some ways, the functionality has
actually increased Ö but let me explain, first of all, how the missing
functions have been implemented. It all revolves round a new key that
doesnæt appear on standard Archimedes keyboard Ö the <FN> key. If you
hold this key down, many of the existing keys take on a new definition
which is printed in green on the front side of the relevant key-tops.

        Numeric keypad emulation

Because there is no numeric keypad (which actually accounts for 18 of
the 20 missing keys) Acorn have provided a numeric keypad emulation.
This is done by using <FN> (like <shift> or <alt>) with keys 7, 8, 9 to
give... 7, 8, 9(!), then U, I, O for 4, 5, 6, and J, K, L for 1, 2, 3.
The keys around them are used for the keys around the matrix of numbers
on the keypad.

It is obviously going to be a nuisance to have to hold down <FN> all the
time, so you can ögo into FN modeò by holding down <FN> and pressing and
releasing <Numlock>. Repeating the process switches FN mode off again.

        Mouse emulation

In case you donæt want to get the mouse out of its carrier, there is a
keyboard mouse emulation provided. Again you use <FN>, or switch into FN
mode, and then the cursor keys move the mouse pointer and <Q>, <W> and
<E> perform the functions of <select>, <menu> and <adjust>.

        Extra keyboard functions

The addition of the <FN> key has enabled Acorn to provide some extra
functionality. There are hot keys: <FN-f9> inverts the video and
<FN-f10> blanks the screen and puts the hard drive to sleep. The <FN>
key is also used to make up for the lack of <f11> and <f12>. The <FN-f1>
combination is equivalent to <f11> and <FN-f2> simulates <f12>. So, for
example, you can shut down the computer with <ctrl-shift-FN-f2> which is
equivalent to <ctrl-shift-f12>.

The other way in which the keyboard is improved is via the use of the
<alt> key to give special characters including accented characters. For
example, <alt-4> gives ╝, <shift-alt-R> gives «, <alt-M> gives ╡, etc.
The accented characters are produced by using <alt> to generate the
accent followed by typing the character onto which the accent is to be
added. This includes acute, grave, circumflex, umlaut, tilde, cedilla
and the one on top of the ┼ whose name I do not know!

        The case

The case is covered with grey 'suedecoat' epoxy resin bonded paint. This
gives a velvety look to the surface which is quite stylish. The only
clue to the contents of the box, when it is closed, is a single Acorn
logo. Once the lid is lifted, you can see the word öAcornò, another
Acorn logo and, on the opposite side, the simple legend, öA4ò Ö but
nothing to say whether it is a model I or a modeláII.

        The carrying case

Acorn have produced a custom-designed carrying case for the A4 (costing
ú35 +VAT). The main compartment of the case houses the A4 and has a
separate subsection for the mouse. On the inside of the lid of this main
compartment are pockets for floppy discs, pens, etc and a large pocket
that would take papers and/or thin manuals. There is then a separate
compartment, with its own zip opening, to take the battery charger and,
possibly, a spare battery-pack. One nice touch is that the case has both
a hand-grip and a shoulder strap Ö and the shoulder strap is easily
detachable via two very firm plastic clips.

        Documentation

The A4 comes with a Welcome Guide, which includes a RISC-OS tutorial, a
RISC-OSá3 User Guide, a RISC-OSá3 Applications Guide and a Portable
Guide. This öportable guideò is well named as it is both a guide to the
portable, and also it is a portable guide Ö i.e. it is only about 25cm ╫
10cm and would slip easily into a pocket or handbag. It is wiro-bound
and has sections marked with cardboard tags so that you can quickly turn
to the section you require. It does not seem to contain any information
that is not included in the A4 Welcome Guide but it represents a very
helpful extract from it for reference purposes öon the moveò.

        Acorn A4 Technical Specifications


Central processing unit

ARM3, 32bit RISC processor with integrated 4kácache, clock rate 24MHz
(6MHz in automatic powersave mode)

Memory

2Mbyte OS ROM.  2Mbyte RAM (model I), 4Mbyte RAM (model II)
        Öá32bit datapath throughout, all memory directly addressable
        Öáclock rate 12MHz (3MHz in automatic powersave mode)

Floppy disc drive

3╜" 2Mbyte (unformatted)
        Öá1.6M, 800k and 640k ADFS formats
        Öá1.44M and 720k DOS formats

Hard disc drive (model II)

2╜" 60Mbyte formatted capacity internal hard drive (IDE interface)
        Öáauto-parking
        Öáautomatic powersaving, software configurable spindown delay

Parallel interface

Industry standard Centronics« compatible (25pin D-type female)
        Öálow level bi-directional capability via OS interface

Serial interface

Industry standard RS232 (9pin D-type male, ATápinout)
        Öá75-9600 baud via OS interface, software rate selectable

Sound system

Two channel, 7 position, 8 voice, full stereo sound system
        Öácompact internal mono speaker
        Öástereo jack socket (32W 3.5mm, for headphones or amplifier)

Display system

Twin layer Formulated Twisted Nematic (FTN) LCD display panel
        Öáfluorescent edgelighter with brightness adjustment
        Öá640 ╫ 480 (VGA) pixel resolution
        Öá182 ╫ 137mm viewing area (4:3 aspect ratio)
        Öá15 greyscale shades via Acorn patented greyscaling engine

Industry standard video interface (15pin VGA D-type female)
        ÖáVGA, VGA+ (256 colour) and SuperVGA (800 ╫ 600)
        Öáautomatic monitor detection and identification

Keyboard -  Internal 83 key UK PC layout with embedded numeric keypad
        Öáfull 3mm travel, force reflex curve

External AT-type keyboard port (6pin miniDIN, PS/2 pinout)

Mouse - Three button ergonomically designed mouse, 200TPI resolution

Battery pack

1800mAh rechargeable Nickel-Cadmium, solid block construction

Mains supply / Charger unit

Separate mains supply / charger unit

        Öáquick and trickle charge rates under control of the power
          management system (around seven hours to full charge)
        Öárecharge time independent of system operation
        Öáauto-ranging mains input (100-240Vac), IEC320 inlet connector

Power management system

On-board independent microprocessor management of battery charging and
power utilisation enables battery life of between 2╜ and 4hrs, dependent
on use)
        Öáminimises power consumption, even between keystrokes
        Öáuser-configurable powersave settings for display blanking and
          hard disc spindown delay
        Öáseparate LCD five segment indicator reflects battery charge
          state
        Öáiconbar battery monitor provides graphical display of charge
          status

Networking

Via optional Econet network interface module
        Öáfull Econet network filing system included in RISC-OS ROM

Operating System

(in 2Mbyte ROM plus applications on disc)

RISC-OS 3.10 second generation co-operative multi-tasking Operating
          System, executing directly from ROM
        Öáseamlessly integrated graphical WIMP user interface
        Öáalmost instant availability (no loading from disc)
        Öásecure (far harder to corrupt than disc-based operating
          systems)
        Öáuses substantially less RAM and disc space than disc-loaded
          alternatives
        Öákey base applications, outline font manager and three font
          families, integrated multi-tasking file management system and
          interactive help application ù all in ROM
        Öámultiple character sets (ISO8859 Latin1 to 4 and Greek)
        Öáadditional applications suite (pre-installed on hard disc
          model)

In ROM:

        Task and memory manager, palette utility and Basic V language
        Alarm   Öáclock and multiple alarm application
        Calc    Öásimple four function desktop calculator
        Chars   Öáfacilitates input of any characters from the set
        Configure       Öádesktop and system configuration utility
        Draw    Öáobject orientated drawing package
        Edit    Öáfully featured text and Basic program editor
        Help    Öáwindow based context sensitive help application
        Paint   Öápixel and sprite editor
        Pinboard        Öáenables objects to be Épinnedæ to the desktop

On disc:  a number of applications including:

        PrintEdit  Öácreate new dot matrix printer definition files
        FontPrint  Öádownloads font definition files to PostScript«
                          printers
        Printers   Öáprinter manager, supports multiple independent
                     printers
        Squash  Öá   file, application and directory compression utility
        Maestro Öá   create, edit, play and print music definition files
        SciCalc Öá   fully functional desktop scientific calculator
                     application
        ChangeFSI Öá high quality image manipulation application
        T1ToFont  Öá converts Adobe« T1 font files to RISC-OS outline fonts

Manuals (included)
        Ö Comprehensive Welcome Guide (including RISC-OS tutorial)
        Ö Portable Guide (ready reference to key aspects when on the
          move)
        Ö RISC-OS 3 User Guide
        Ö RISC-OS 3 Applications Guide

Physical

Robust polycarbonate main unit enclosure, sub-micron copper plated with
nickel overplate inside and out; 'suedecoat' epoxy resin bonded paint on
external surfaces.

Computer unit: 297 ╫ 210 ╫ 53mm, weight 2.3kg (excluding battery)
Mains supply unit: 147 ╫ 74 ╫ 44mm, weight 420g (excl. 2m mains lead)
Battery pack: 140 ╫ 111 ╫ 25mm, weight 720g
Mouse:  100 ╫ 60 ╫ 30mm, weight 120g (including 1.8m lead)

Environmental
Operating: +5 to +35░C, 10 to 80% RH, up to 2,500m altitude
Non-operating: Ö10 to +60░C, 5 to 95% RH, up to 10,000m altitude

Standards Compliance

Designed, manufactured and type-tested to EN60950 (BS7002).
Manufacturing facility registered to BS5750 part 2.

Options

ALA67   Shoulder bag ù for ease of transporting system, manuals, charger
unit and accessories such as spare battery packs Öáú35 +VAT

ALA60   2 Mbyte RAM upgrade (i.e. model I upgrade to 4 Mbyte) Ö ú110 +VAT
ALA62   60 Mbyte internal Hard Disc upgrade Ö ú350 +VAT
ALA65   Additional battery pack Ö ú50 +VAT
ALJ22   Acorn A4 Technical Reference Manual ú65 (no VAT)
AKA70   PC Emulator (v1.8) ú99 +VAT

Comments

Looking at the information we have got so far about the A4, various
thoughts come to mind Ö here they are, as random jottings...

The opposition

I went along to the local Apple Centre to have a look at the Powerbook
series of computers Ö the direct rivals to the A4. The A4 is certainly
more powerful than the mid-range 140 series Powerbooks and is roughly
comparable with the top-end 170 series. Certainly, the screen display of
the A4 is very noticeably faster than the 170 although, having a maths
co-processor, the 170 may have the edge on computation speed.

To set the comparison in context, the Powerbook 140 with 4M RAM and a
40M drive costs ú1995 and the 170 with 4M RAM and an 80M drive is ú3150
Ö getting on for twice the price of the 4M/60M A4 at ú1699. Remember too
that 4M ram on an Apple is NOT equivalent to 4M on an Acorn machine. The
operating system on the Apple consumes a huge amount of RAM (in contrast
to Acornæs OS which is in ROM and uses RAM only for workspace) and the
Mac applications take up a lot more RAM than Acornæs applications. For
example, on a 4M Mac, I could only just fit PageMaker and MS Word with
not a lot of room to spare.

The display resolution of the Powerbooks is only 640 ╫ 400 Ö even on the
170 series Ö whereas the A4 is 640 ╫ 480. The 140 series screens seem to
be the same as the A4 in terms of the way that moving objects are rather
blurred. However, the 170æs screen uses a different type of LCD screen
which seems much more responsive and doesnæt have the same blurring
effect on moving objects.

External keyboard

What a good idea it was to provide the facility for an external AT-type
keyboard! Now anyone who wants a really top-notch keyboard can buy one
and can attach it to an A4. For high-speed secretaries used to using
high-quality keyboards, this is good news. (I wonder if this means that,
when RISC-OS 3.10 appears, we will be able to add an AT keyboard to the
A5000? The hardware is there already Ö itæs just a question of whether
we will be able to get at the RISC-OS code needed to run the external
keyboard.)

Wot! no trackerball?

Acorn have gone against the norm by choosing to provide a mouse with the
portable and not a trackerball as, for example, with the Powerbook
computers. They have a 64-key keyboard at the back of the case with a
trackerball right in the middle of the front of the case. The idea is
that, as your fingers are over the keys, your palms can rest on the
edges of the case and your thumbs are over the trackerball. I didnæt
like this arrangement as it requires a completely different technique
for operating the trackerball Ö very different from the way you use a
mouse. It certainly wouldnæt have worked well for the RISC-OS desktop
because of the use of three buttons instead of the Macæs single button.

In the circumstances, I think the choice of a mouse was a wise move. The
case is VERY tightly packed already and the addition of a trackerball
would have necessitated a bigger case. Also, it is difficult to see
where, ergonomically, you could have placed a three-button trackerball
relative to the keyboard.

If you only want to start up an application and get typing, the
keyboard-mouse simulation will be quite adequate and if you really need
to do some heavy mouse-work, all you need to do is find a space to lay
down an A4-sized book and do your mousing on the back of that Ö it forms
quite an effective mouse mat for the Logitech mice because they use
rubber balls.

All-in-all, I think it was sensible to go for keeping the mouse-addicts
happy at the risk of incurring the wrath of trackerball fans. In any
case, they can still take their trackerballs along with them and plug
them in instead of the mouse. (Does anyone know of a smaller,
self-contained trackerball than the rather bulky Marconi one?)

Connectivity issues

One possible criticism, especially when comparing with the Powerbooks,
is the lack of connection to an external hard drive. The Powerbooks have
a SCSI drive (albeit rather slower than the A4æs IDE drive!) and also
have a connector for an external SCSI drive. This makes transferring
data to and from the portable much easier than on the A4.

Acorn would argue that you can use the Econet interface for data
transfer but thatæs no better than the Powerbook which has an Appletalk
connector. Also, what about customers who have a single Archimedes of
some sort and want to use it with an A4? It isnæt going to be economical
for them to buy a complete Econet system just to transfer files from one
to the other.

What we need is some enterprising programmer to write an RS232 filing
system and sell it with an appropriate lead to link two Archimedes
computers together. At 9,600 baud you would be transferring at about 8
kbytes/second and if the file transfer had automatic
compression/decompression, this could probably be doubled. (There is no
shortage of processor speed at either end!)

The only other possibility I can think of is using the Centronics
interface, which is bi-directional. However, this would only work
between A4 and A5000 as they are the only Acorn computers that have the
bi-directional facility. I have no idea what sort of speed could be
achieved. Does anyone else know?

Stone me! Literally a couple of hours after I wrote that last section, I
was given details of Atomwideæs forth-coming öRemoteFSò. This is a
filing system that will allow two computers to access each otheræs
drives independently, from the desktop as a multi-tasking background
task. The physical link could be two modems or a direct RS232 link,
Ethernet interfaces or a direct connection via the parallel port . The
latter interface would give transfer speeds in excess of 300 kbytes/sec
i.e faster than ST506 hard drives and about the same speed as a small
SCSI hard drive.

öAh, but the A4 only has an Econet interface, not Ethernetò Ö if you
hang on, there will soon be an Ethernet interface for the A4 that runs
via the parallel printer port Ö those clever chaps at Atomwide again!

Both products are supposed to be available in the fourth quarter 1992,
i.e. they should be in good time for the A4 itself.ááThe cost of the
software plus a parallel printer cable will be ösomewhere in the region
of ú50ò.

Hardware notes

For those interested in the internal hardware of the A4, the first and
most obvious comment is that the circuit board is very compact.
Virtually all that goes on an A5000 pcb has been fitted into a space no
more than 280mm ╫ 85mm. (The A5000 keyboard measures 300mm ╫ 240mm and
the 2M to 4M upgrade is on a separate p.c.b.)

We didnæt dare take a screwdriver to the portable we were examining (one
of only two at Fulbourn Road at the time) so all we could do was to lift
off the hatch into which the Econet interface is fitted. The RAM seems
to consist of four 1 Mbyte RAM chips and the 2 Mbytes of ROM are set up
on an amazing header mechanism so that the ROM chips are actually
stacked on top of the RAM chips. There is an auxilliary ROM socket (as
on the A5000) and that contains a ROM with the battery manager utility
and a few other portable-specific modules in it.

The only other point to note is that all the components that we could
see, apart from the ROMs, were, not surprisingly, soldered directly to
the circuit board.

Software notes

It may be of interest to some of you to see the modules list for the A4.
Those in italics do not appear, as far as I can see, on the A5000.

MOS Utilities   3.10 (30 Apr 1992)
Podule Manager  1.26 (09 Dec 1991)
FileSwitch      2.08 (15 Apr 1992)
ResourceFS      0.14 (12 Mar 1992)
UK Messages     0.45 (03 Apr 1992)
MessageTrans    0.23 (30 Mar 1992)
Territory Mgr   0.13 (25 Apr 1992)
UK Territory    0.18 (30 Apr 1992)
Window Manager  3.16 (30 Apr 1992)
Desktop 2.43 (02 Apr 1992)
Task Manager    0.75 (25 Apr 1992)
!Alarm  2.37 (24 Apr 1992)
!Calc   0.52 (01 Apr 1992)
!Chars  1.13 (01 Apr 1992)
!Help   2.19 (01 Apr 1992)
Printers        0.34 (23 Apr 1992)
ADFSFiler       0.61 (23 Apr 1992)
ARM3 Support    1.09 (11 Dec 1991)
BBC BASIC V     1.05 (10 Apr 1992)
BASICTrans      1.00 (05 Mar 1991) English
Buffer Manager  0.22 (14 Apr 1992)
Colour Selector 1.07 (15 Apr 1992)
Debugger        1.39 (13 Apr 1992)
DeviceFS        0.26 (09 Mar 1992)
Drag A Sprite   0.03 (12 Dec 1991)
Drawing Module  1.05 (03 Mar 1992)
FileCore        2.41 (06 Apr 1992)
ADFS    2.67 (28 Apr 1992)
Filer   1.64 (23 Apr 1992)
FilerSWIs       0.03 (04 Mar 1992)
Font Manager    3.07 (30 Apr 1992)
FPEmulator      2.87 (09 Dec 1991)
Free    0.21 (11 Apr 1992)
Hourglass       2.08 (27 Mar 1991)
IIC     0.12 (28 Apr 1992)
International   1.24 (22 Apr 1992)
IRQ Utils       2.50 (11 Sep 1989)
NetFiler        0.72 (03 Feb 1992)
NetStatus       2.06 (01 May 1991)
Obey    0.29 (23 Apr 1992)
Palette Utility 0.45    (24 Mar 1992)
Parallel Device 0.34 (17 Mar 1992)
Printer sharer  3.18 (30 Mar 1992)
Printer driver  3.28 (31 Mar 1992) for bit image printers
PDumper Support 0.11 (23 Apr 1992)
PDumperDM       0.34 (25 Apr 1992)
Intæl Keyboard  0.31 (04 Mar 1992)
Pinboard        0.50 (23 Apr 1992)
PipeFS  0.13 (11 Dec 1991)
Portable        0.29 (22 Apr 1992)
RAMFSFiler      0.28 (12 Mar 1992)
ResourceFiler   0.12 (03 Feb 1992)
ROM Fonts       0.14 (01 Apr 1992)
RTCAdjust       0.03 (27 Mar 1991)
ScreenBlanker   2.15 (25 Apr 1992)
Serial Device   0.21 (06 Mar 1992)
Serial Support  0.17 (03 Feb 1992)
ShellCLI        0.25 (10 Dec 1991)
SoundDMA        1.20 (01 Mar 1992)
SoundChannels   1.27 (22 Apr 1992)
SoundScheduler  1.17 (30 Apr 1992)
SpriteExtension 0.46 (23 Apr 1992)
SpriteUtils     1.09 (10 Dec 1991)
Squash  0.21 (27 Feb 1992)
SuperSample     0.07 (12 Dec 1991)
System Devices  1.25 (02 Sep 1991)
TaskWindow      0.47 (23 Apr 1992)
Window Utils    2.50 (11 Sep 1989)
Filter Manager  0.08 (22 Apr 1992)
WaveSynth       1.13 (20 Mar 1992)
StringLib       1.11 (23 Mar 1992)
Percussion      1.10 (23 Mar 1992)
C Library       3.99 (23 Apr 1992)
Filer_Action    0.29 (13 Mar 1992)
!Configure      1.41 (30 Apr 1992)
!Draw   0.88 (25 Apr 1992)
!Paint  1.61 (23 Apr 1992)
!Edit   1.44 (09 Apr 1992)
DOSFS   0.43 (26 Apr 1992)
BatMgr  0.07 (25 Apr 1992)

Technical note

Tim Caspell of Acorn answers two technical questions about the LCD
display.

öWhy 15 greyscales, not 16?ò

RISC-OS maps the 8 grey tones and 8 colours through VIDC into a
luminance value. Greyscaling is then achieved in hardware using a ratio
of OFF to ON time. This ratio has to be sensible and 50:50 mid-grey is a
sensible mid-point to achieve the best contrast. Accordingly, the
hardware divides the 100% ON and the middle 50% ON point into 8 shades
and then inverts to achieve the other 8 shades. Thus 50% ON, inverted,
is also 50% OFF, i.e. greyscales 7 and 8 are the same shade:

100% ON         50% ON   50% OFF       100% OFF

|                    |   |                    |

0  1  2  3  4  5  6  7 = 8  9 10 11 12 13 14 15

                      ÿÿ-

              identical mid-grey

öWhy not 32 or even 64 shades?ò

Time domain multiplexed greyscaling is a compromise between contrast
ratio and the onset of perceptible flicker or graining. It becomes
progressively harder to distinguish between adjacent shades as the
number of shades increases, but flickering of individual pixels becomes
more obvious on passive display technology as the ON time becomes
shorter relative to the OFF time at a given frame rate. The font manager
uses only 16 shades for good anti-aliased text and little is gained by
doubling the number of shades whilst flicker starts to become apparent.

Conclusion

Compared with the opposition Ö the Apple Powerbooks Ö the A4 looks
really impressive. Once again, in terms of speed (and that includes
processor speed, display speed and hard drive speed), Acornæs RISC
technology wins again. If you need high computational speed for
maths-intensive applications, the 170 series may have the edge over the
A4 Ö but it costs nearly twice as much.

My only reservation is whether there are enough people out there who
actually need (want?) a portable. Will Acorn sell enough to pay for the
development costs? If you just want a portable for remote text entry,
the Z88 represents a cheaper alternative, albeit with an inferior
keyboard. Is a powerful portable like the A4 more than just an executive
toy? (Iæd be interested to hear your views on this issue.)

Anyway, if you do want a örealò portable computer and not just a remote
text entry system, the A4 is a winner Ö it is a portable power-house!ááA