Why 27 colors on the amstrad cpc ?
genty guillaume
Hello,
Does anybody knows why the amstrad cpc offers a choice of 27 different colors ?
On others computers the total number of colors is always a power of 2 (2, 4, 8, 16, 32
etc), so 32 colors or 16 colors should be more logical for the cpc.
Is there any technical reason for this number of 27 colors ?
Regards.
Guillaume Genty.
Martyn Lycett
genty guillaume wrote in message <34655D...@hol.fr>...
Yes there is.
Don't confuse the display of colours by the screen hardware with the
storage of a pixel's colour by the firmware:
In all cases, of all colour computers, (and TV) the picture is made up
of three primary colour guns which are under independant control of
the driving circuitry. Each gun can vary in intensity and this mixture
forms all the colours we see on the screen.
A TV and the PC driver circuitry produces an analogue output which can
vary any one of the guns from zero to full intensity. This produces,
in theory, an infinite number of colours possible. However, because
our video memories are not infinite, we have to cut down the number of
colours used to a size that the machine's firmware can handle. This
depends on how many bits are used to represent each pixel on the
screen. The more bits, the more possible colours each pixel can store.
Because memory is inherently binary, the number of colours therefore
tends to be a power of two. (256, 65536, etc). This also works for the
CPC, in that the screen memory limits the number of colours in the
firmware to 2, 4 or 16, depending on the mode you are in. Again, all
powers of two.
Not so the hardware. Its RGB signal generator is purley digital, not
analogue, and each gun can have one of only three states: Off, Half,
and Full intensity. This gives a possible 27 combinations. (3 guns
with three possible states each = 3 ^3 = 27). Write them all out if
you don't believe me, there's only 27 of them after all!
So the Screen Pack (as defined in Soft 968) has the job of translating
between the 27 available colours in the machine's pallette, and the 2,
4, or 16 colours that can be stored in the screen memory at any one
time. For this reason, Amstrad chose to call the pallette, 'colours',
and the displayed colours, 'inks'. Which is why you have to define
what colour each ink is going to be before you use it (assuming you
aren't happy with the default settings....)
Just to confuse things even more, each ink actually has TWO colours
associated with it, and these two colours are displayed alternately in
sequence. So if they are defined to be the same colour, the ink is
that constant colour. If they are defined to be two different colours,
then pixels displayed in that ink will flash between the two colours.
*******
Thats right, isn't it Roland?
However, a more important question, and far more vital to the
continuing future of the universe, is: Why "Soft 968". What happened
to Softs 1 to 967?
Martyn
m...@btinternet.com
Martyn
Andrew P. Cadley
On Mon, 10 Nov 1997, David Long wrote:
> On Sat, 8 Nov 1997, genty guillaume wrote:
>
> > Does anybody knows why the amstrad cpc offers a choice of 27 different colors ?
> > On others computers the total number of colors is always a power of 2 (2, 4, 8, 16, 32
> > etc), so 32 colors or 16 colors should be more logical for the cpc.
> > Is there any technical reason for this number of 27 colors ?
>
> 3 x 3 x 3 = 27.
>
*or*
16 x 16 x 16 = 4096
if you've got a plus :-)
> Red/green/blue values can be either 0, 1 or 2. At least, I think that was
> how it worked...
Yup.
AndyC
Sam Holloway
>However, a more important question, and far more vital to the
>continuing future of the universe, is: Why "Soft 968". What happened
>to Softs 1 to 967?
And, for that matter, what about Soft 968 itself? I had MURDER trying to get a
copy over my six years on the CPC, and had to wait for that nice ring-bound
jobby that came out much later on...
Sam
----------------------------------------
The number you have dialled is imaginary
Please rotate your phone by pi/2 radians
and try again. Thankyou.
Sam Holloway sr...@cam.ac.uk
----------------------------------------
Brian Watson
In article <646g81$i...@argon.btinternet.com>
m...@btinternet.com "Martyn Lycett" writes:
...after a very clear explanation of the colour display system..
>
> However, a more important question, and far more vital to the
> continuing future of the universe, is: Why "Soft 968". What happened
> to Softs 1 to 967?
An apparently trivial question, but one not asked before. What WAS the
thinking (if any) behind the numbering sequence of the SOFT publications?
--
Brian Watson
:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
:: Protext Robot Software Pipeline Parados 8BIT IEBA WACCI Publicity ::
:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
Roland Perry
In article <646g81$i...@argon.btinternet.com>, Martyn Lycett
<m...@btinternet.com> writes
>However, because
>our video memories are not infinite, we have to cut down the number of
>colours used to a size that the machine's firmware can handle.
In the case of the CPC (and probably most other personal computers up to
IBM-VGA) the limiting factor on the number of different colours in the
palette is the cost of the Palette-RAM and the number of pins on the
main chip. More "levels" for each colour will mean more pins are
required.
>the screen memory limits the number of colours in the
>firmware to 2, 4 or 16, depending on the mode you are in. Again, all
>powers of two.
The screen memory limits the number of colours you can have on the
screen *at any one time*. As you say, usually 2, 4, 16, 256 etc.
>Not so the hardware. Its RGB signal generator is purley digital, not
>analogue, and each gun can have one of only three states: Off, Half,
>and Full intensity. This gives a possible 27 combinations. (3 guns
>with three possible states each = 3 ^3 = 27).
The CPC produces 3 levels from each colour, with only one pin on the
chip. It does this by a cunning and innovative use of tri-state outputs,
that can be High, low, or floating (which is then set to 'half' by an
external resistor network). As you've described, this allows 27
different colours; with another set of resistors giving a true 27-step
grey scale on a B&W monitor. Other home computers available at the time
tended to have only 8 colours and 8 palette entries, with a B&W monitor
showing Black and <everything else as white>.
To choose which colour is associated with each palette position, there's
a RAM which has a 5-bit (32 possibilities) 'in' and the tristate RGB
'out'. Five of the colours are repeated, but ignored.
>So the Screen Pack (as defined in Soft 968) has the job of translating
>between the 27 available colours in the machine's pallette, and the 2,
>4, or 16 colours that can be stored in the screen memory at any one
>time.
The graphics controller displays either the first 2, 4 or 16 entries in
the pallette, each of which can be set to a 'random' choice of any of
the 27 different displayable colours.
>Just to confuse things even more, each ink actually has TWO colours
>associated with it, and these two colours are displayed alternately in
>sequence.
That's done entirely by software that reloads the pallette RAM every
time there's a relevant "ticker" interrupt.
>However, a more important question, and far more vital to the
>continuing future of the universe, is: Why "Soft 968". What happened
>to Softs 1 to 967?
I don't remember exactly, but I'm gpoing to make a wild semi-informed
guess and say it's because it was *Amstrad's* 968th product, that just
happened to be classed as 'software'.
--
My email address is: | "Time is an illusion.
roland at perry dot co dot uk | Launch times doubly so".
Keith M. Lucas
In article <Pine.SOL.3.95.971110010640.6963B-100000@holly>,
David Long <cs...@csv.warwick.ac.uk> wrote:
>Red/green/blue values can be either 0, 1 or 2. At least, I think that was
>how it worked...
Yes. Colour=red*3+blue+green*9.
Hence:
0=black, 1=50%blue, 2=100%blue,3=50%red..
Now for a complex question. What the HELL was with the hardware
colours these mapped to and WHY ??? I spent AGES trying to work out
what the hardware colours were for. I could understand if they'd
mapped to 6 bit ones, 2 bits per colour channel, but 5 bits made no
sense.
>Room 101 JM4, Jack Martin Residences, University of Warwick, Coventry, CV4 7AL
A rich bugger who can afford JM. I had to live on flaming
Westwood... mutter, complain, winge !
-------------------------------------------------------------------------------
sillywizATexcessionDOTdemonDOTcoDOTuk"It's not a personality..it's a bulldozer"
-------------------------------------------------------------------------------
"Great boiling hell, Jones, what happened ?" "Er.. I think my pants exploded."
---------------------------------------------------------- Captain Star -------
David Long
On Sat, 8 Nov 1997, genty guillaume wrote:
> Does anybody knows why the amstrad cpc offers a choice of 27 different colors ?
> On others computers the total number of colors is always a power of 2 (2, 4, 8, 16, 32
> etc), so 32 colors or 16 colors should be more logical for the cpc.
> Is there any technical reason for this number of 27 colors ?
3 x 3 x 3 = 27.
Red/green/blue values can be either 0, 1 or 2. At least, I think that was
how it worked...
--
David Long [D.C....@warwick.ac.uk] 1st year CS student at Warwick University
Room 101 JM4, Jack Martin Residences, University of Warwick, Coventry, CV4 7AL
========================= Louise Woodward is innocent. =======================
Richard Fairhurst
genty guillaume <guillau...@hol.fr> wrote:
> Does anybody knows why the amstrad cpc offers a choice of 27 different
> colors ? On others computers the total number of colors is always a power
> of 2 (2, 4, 8, 16, 32 etc), so 32 colors or 16 colors should be more
> logical for the cpc. Is there any technical reason for this number of 27
> colors ?
3 to the power of 3 - red, green, blue with three brightness levels.
--
Richard Fairhurst http://www.systemed.u-net.com/
A million years on and still in trouble:
put down your fists and enter with a shovel
Martin Bullivant
>
> Does anybody knows why the amstrad cpc offers a choice of 27 different
colors ?
> On others computers the total number of colors is always a power of 2 (2,
4, 8, 16, 32
> etc), so 32 colors or 16 colors should be more logical for the cpc.
> Is there any technical reason for this number of 27 colors ?
>
Guillaume,
You could assign colours 28 through to 31 if you wished as well, although
these were only repeats of the earlier colours.
So the statement INK 1,31 is valid.
Regards, Martin
Cliff Lawson
colors ?
It's because 3 to the power 3 is 27!
You've got Red, Green and Blue video lines (so that's the first 3) and each
one of those could be in one of 3 states - off, mid-intensity and on (so
that's you second three) and to get every combination of off, mid, on on
every one of the RGB lines is easily calculated as 3 to the power 3 = 27.
Quad erat demostrandum.
The CPC and it's monitor were a little unusual to drive the RGB in analog so
that (not entirely sure of these figures) off=0V, mid=0.5V and on=1V (say).
On other peoples computers the RGB tended to be just on or off so you got
2^3 colours = 8 or there would be a fourth line (intensity) which was also
binary meaning either hi or low colour which therefore gave you 2^4=16
colours. This was how the 16 colour modes worked on both the PC1512 and
PC1640 in EGA mode that we produced.
When IBM finally introduced the VGA graphics adapter and accompanying VGA
monitors they went for a system were each of the three RGB lines could be at
one of 8 distinct voltages (=intensity levels) which gave 2^8=256 colours.
Cliff, Amstrad plc
=======================================
mailto:cli...@amstrad.com
http://web.ukonline.co.uk/cliff.lawson/index.htm
=======================================
Cliff Lawson
Sam Holloway wrote in message ...
>>However, a more important question, and far more vital to the
>>continuing future of the universe, is: Why "Soft 968". What happened
>>to Softs 1 to 967?
Because all books and software including all the CPC tapes and discs were
SOFT nnn so it may well have been the 968th product. For example the DDI-1
firmware manual is SOFT158A. It probably isn't actually the 968th because it
could have been that 9nn meant 6128 product or somthing like that so maybe
it was the 68th 6128 product.
>And, for that matter, what about Soft 968 itself? I had MURDER trying to
get a
>copy over my six years on the CPC, and had to wait for that nice ring-bound
>jobby that came out much later on...
Err, every copy of SOFT 968 ever printed was a "nice ring-bound" jobby. It
never existed as a properly bound soft or hard back book.
Cliff
Simon Forrester
> And, for that matter, what about Soft 968 itself? I had MURDER trying to
get a
> copy over my six years on the CPC, and had to wait for that nice ring-bound
> jobby that came out much later on...
I had to wait 'til Amstrad Action - they had two copies just sitting there!
--
Simon Forrester http://www.futurenet.com sforr...@futurenet.com
-SFNet- -cult tv- -MacWeb-
Trek, B5, Dwarf, For the cooler kind THE independent UK
and loads more of couch potato Mac resource
Herman Dullink
>On other peoples computers the RGB tended to be just on or off so you got
>2^3 colours = 8 or there would be a fourth line (intensity) which was also
>binary meaning either hi or low colour which therefore gave you 2^4=16
>colours. This was how the 16 colour modes worked on both the PC1512 and
>PC1640 in EGA mode that we produced.
This is CGA. The EGA could do the same as the CGA and/or MDA, but for ECDs
(EGA displays) 2 pins for each colour is used giving 2^2^3 = 64 colours.
>When IBM finally introduced the VGA graphics adapter and accompanying VGA
>monitors they went for a system were each of the three RGB lines could be
at
>one of 8 distinct voltages (=intensity levels) which gave 2^8=256 colours.
The VGA uses three 6-bit DACs giving 2^6^3 = 262144 colours or 64 shades
of grey as the monochrome VGA display only used the green pin.
Herman
Martyn Lycett
Martin Bullivant wrote in message
<01bceea2$6d5daea0$26fd...@PSW19308.WHITBREAD.COM>...
>>
>> Does anybody knows why the amstrad cpc offers a choice of 27
different
>colors ?
>> On others computers the total number of colors is always a power of
2 (2,
>4, 8, 16, 32
>> etc), so 32 colors or 16 colors should be more logical for the cpc.
>> Is there any technical reason for this number of 27 colors ?
>>
>
>Guillaume,
>
>You could assign colours 28 through to 31 if you wished as well,
although
>these were only repeats of the earlier colours.
>
>So the statement INK 1,31 is valid.
>
>Regards, Martin
>
Well it looks that way, but in fact thats not what happens. The
Firmware does a binary mask of the colour given to it to force it
below 27 B4 it assigns the colour. It is possible to get round this in
machine code, but BASIC will just use the firmware routines provided.
So while you think you are accessing duplicate colours above 27, you
are actually getting colours below 27.
Its an academic point, really....
Martyn
m...@btinternet.com
Divine
>>Room 101 JM4, Jack Martin Residences, University of Warwick, Coventry, CV4 7AL
>
>Westwood... mutter, complain, winge !
The Westwood Dining Scheme - bargain! ;-)
Bye,
Divine
Roland Perry
In article <EJG60...@excession.demon.co._delete_this_.uk>, "Keith M.
Lucas" <sill...@excession.demon.co._delete_this_.uk> writes
>I could understand if they'd
>mapped to 6 bit ones, 2 bits per colour channel, but 5 bits made no
>sense.
27 different displayable colours can be mapped into 5 bits (32
possibilities, so there are 5 duplicates).
Having 5 bits saves gate-count inside the ULA, and in this case allowed
us to fit in such a multicoloured scheme *at all*. The alternative would
have been to use 4 bits, giving the more conventional scheme of 8
colours + 8 bright colours; much less sexy!!
David Long
On Mon, 10 Nov 1997, Keith M. Lucas wrote:
> Now for a complex question. What the HELL was with the hardware
> colours these mapped to and WHY ??? I spent AGES trying to work out
> what the hardware colours were for. I could understand if they'd
> mapped to 6 bit ones, 2 bits per colour channel, but 5 bits made no
> sense.
IIRC the only colour numbering scheme that made sense was the CP/M colour
numbers, if you converted it into binary it was in RGB format or
something. However I may be completely wrong :-)
> >Room 101 JM4, Jack Martin Residences, University of Warwick, Coventry, CV4 7AL
>
> A rich bugger who can afford JM. I had to live on flaming
> Westwood... mutter, complain, winge !
At least you got some of your meals cooked for you, even if you did have
to walk miles to get to the main campus :-)
--
David Long [D.C....@warwick.ac.uk] 1st year CS student at Warwick University
Room 101 JM4, Jack Martin Residences, University of Warwick, Coventry, CV4 7AL
I\I I I/I |=========================================================> 9" nail?
Nich Campbell
Keith M. Lucas wrote:
> Yes. Colour=red*3+blue+green*9.
>
I once worked that out on a boring Saturday morning.
> Now for a complex question. What the HELL was with the hardware
> colours these mapped to and WHY ???
I'm told that there is absolutely no logical layout to the hardware
colours at all.
--
Nicholas "Nich" Campbell (N.A.Ca...@durham.ac.uk)
Angela Cook
Brian Watson wrote in message <879193...@spheroid.demon.co.uk>...
>In article <646g81$i...@argon.btinternet.com>
> m...@btinternet.com "Martyn Lycett" writes:
>
>...after a very clear explanation of the colour display system..
>>
>> However, a more important question, and far more vital to the
>> continuing future of the universe, is: Why "Soft 968". What happened
>> to Softs 1 to 967?
>
>An apparently trivial question, but one not asked before. What WAS the
>thinking (if any) behind the numbering sequence of the SOFT publications?
I think some had certain prefixs depending on whether they were tape or
disc, I don't know about general "books" though.
- Angela
Angela Cook
Simon Forrester wrote in message ...
>In article <srh28.23...@cam.ac.uk>, sr...@cam.ac.uk (Sam Holloway)
wrote:
>
>> And, for that matter, what about Soft 968 itself? I had MURDER trying to
>get a
>> copy over my six years on the CPC, and had to wait for that nice
ring-bound
>> jobby that came out much later on...
I've got a few sitting around now if any one still is in need.
>I had to wait 'til Amstrad Action - they had two copies just sitting there!
Future is sometimes good on things like that (though whatever happened to
the CPC's Simon Stansfield wouldn't let any one have?). I got a black Future
mug a few years back, broke the handle and now use it as a pen holder.
- Angela
Roland Perry
In article <3469CB...@durham.ac.uk>, Nich Campbell
<N.A.Ca...@durham.ac.uk> writes
>I'm told that there is absolutely no logical layout to the hardware
>colours at all.
It's very "logical". It's an arrangement that allows conversion from the
32 different hardware colours (5 repeated) to the 27 displayable colours
using the least possible number of ULA gates to do the work.
Andrew Cadley
Roland Perry wrote:
>
> In article <646g81$i...@argon.btinternet.com>, Martyn Lycett
> <m...@btinternet.com> writes
> The screen memory limits the number of colours you can have on the
> screen *at any one time*. As you say, usually 2, 4, 16, 256 etc.
^^^^^^^^^^^^^^^^^
*Unless* you change the palette register part way through the screen.
:-)
AndyC
Brian Watson
In article <64cq6s$ooq$1...@nclient5-gui.server.virgin.net>
angela...@virgin.net "Angela Cook" writes:
>
> Future is sometimes good on things like that (though whatever happened to
> the CPC's Simon Stansfield wouldn't let any one have?). I got a black Future
> mug a few years back, broke the handle and now use it as a pen holder.
>
> - Angela
Black Future?
Sounds like a new game title. Or perhaps Games Workshop would sue.
Marcus Durham
In article <64cq6s$ooq$1...@nclient5-gui.server.virgin.net>, Angela Cook
<angela...@virgin.net> cheerily wrote:
[snip]
>Future is sometimes good on things like that (though whatever happened to
>the CPC's Simon Stansfield wouldn't let any one have?). I got a black Future
>mug a few years back, broke the handle and now use it as a pen holder.
I once won a tenner in an issue of AA. I never saw it. It was in that
issue of AA with the map of the English Channel on the front (I think).
Anyone here get their picture in AA at somepoint (exluding people called
Richard and Simon who worked for AA). :-)
However, I won two Your Sinclair badges for getting letters published.
I've lost them though. What I really wanted was a Trainspotter of my
very own. :-(
--
Marcus E. Durham
http://www.zenn.demon.co.uk/index.htm
"We're the Sweeney son and we haven't had our dinner"
David Long
On Wed, 12 Nov 1997, Marcus Durham wrote:
> I once won a tenner in an issue of AA. I never saw it.
I won a copy of Chuckie Egg on tape in the last competition AA ever ran,
with the price sticker still on it, and also a piece of cake in their
(5th?) birthday competition. Very nice it was too, IIRC :-)
Lazy Bone
> > colours these mapped to and WHY ???
>
greenscreen monitors. Check out the pictures on my homepage if you
have a greenscreen - almost photo quality on a CPC using 27 shades of
green - but they look damn ugly on a colour monitor.
http://www.alphalink.com.au/~zhulien/JPCsoftware.htm
Regards
Julian Cassin
(PS - well not really photo quality, but pretty good for a CPC)
Matthew Breckon
I won a tenner for writing the solution to Lopears (great game ;-)
Apart from that never got anything else in it's hallowed pages, sniff sniff
;-)
Matt
Andrew P. Cadley
On 13 Nov 1997, Lazy Bone wrote:
> > > colours these mapped to and WHY ???
> >
> Could be something to do with having proper 27 shade green-scale on
> greenscreen monitors. Check out the pictures on my homepage if you
> have a greenscreen - almost photo quality on a CPC using 27 shades of
> green - but they look damn ugly on a colour monitor.
>
> http://www.alphalink.com.au/~zhulien/JPCsoftware.htm
Will take a look, but I bet they don't look quite as nice as some of the
colour pictures I've converted to the pluses ;-)
AndyC
Roland Perry
In article <34699F...@uea.ac.uk>, Andrew Cadley
<A.P.C...@uea.ac.uk> writes
>*Unless* you change the palette register part way through the screen.
True. You can also change mode part way down as well.
Simon Matthews
Marcus Durham wrote:
>
> <snippage>
>
> I once won a tenner in an issue of AA. I never saw it. It was in that
> issue of AA with the map of the English Channel on the front (I think).
> Anyone here get their picture in AA at somepoint (exluding people called
> Richard and Simon who worked for AA). :-)
Me too. Unfortunately taken in Rob's flat at Plumstead in front of the
most hideous curtains you have ever seen. Oh, and on a bad hair day as
well.
--
+------------------------------------+-------------------------------+
| Simon Matthews | Do you hear what I hear? |
| s.j.ma...@nospam.lhmc.ac.uk | Bittering distress, |
| Remove "nospam" to reply | Who decides what you express? |
| Spam will be returned in spades | "Eye" ....And Justice for All |
+------------------------------------+-------------------------------+
| Fenster : I had some guy's fingers in my asshole tonight! |
| Hockney : Is it Friday already? |
| Fenster : F*ck you! I'll never shit right again. |
+-------------------------------------------------The Usual Suspects-+
Richard Fairhurst
Roland Perry <nos...@affordable.co.uk> wrote:
> True. You can also change mode part way down as well.
Or part way across if you're really clever, as Kevin will testify...
Richard Fairhurst
Simon Matthews <s.j.ma...@nospam.lhmc.ac.uk> wrote:
> [AA pictures]
> Me too. Unfortunately taken in Rob's flat at Plumstead in front of the
> most hideous curtains you have ever seen. Oh, and on a bad hair day as
> well.
The infamous STS/Quantum article, I presume?
Keith M. Lucas
In article <64bqv5$i...@lily.csv.warwick.ac.uk>,
Divine <div...@dcs.warwick.ac.uk> wrote:
>>>Room 101 JM4, Jack Martin Residences, University of Warwick, Coventry, CV4 7AL
>>
>>Westwood... mutter, complain, winge !
>
I thought it was pants when I heard about it and I think it's pants
now. I ate there ONCE during the whole time I was on Westwood and that
was ENOUGH, having to have paid for not doing so would have been the
final straw, and I'd have been forced to burn down some sculptures in
protest.
-------------------------------------------------------------------------------
sillywizATexcessionDOTdemonDOTcoDOTuk"It's not a personality..it's a bulldozer"
-------------------------------------------------------------------------------
"Great boiling hell, Jones, what happened ?" "Er.. I think my pants exploded."
---------------------------------------------------------- Captain Star -------
Ivar Fiske
Lazy Bone wrote:
> greenscreen monitors. Check out the pictures on my homepage if you
> have a greenscreen - almost photo quality on a CPC using 27 shades of
> green - but they look damn ugly on a colour monitor.
>
> http://www.alphalink.com.au/~zhulien/JPCsoftware.htm
I couldn't save these arc-files. They just showed up on the screen as
weird text when I clicked on the links. I'm using Netscape 3.03 Gold.
----
Ivar Fiske
Richard Fairhurst
Andrew P. Cadley <w962...@cpca6.uea.ac.uk> wrote:
> On 13 Nov 1997, Lazy Bone wrote:
>
> > Check out the pictures on my homepage if you
> > have a greenscreen - almost photo quality on a CPC using 27 shades of
> > green - but they look damn ugly on a colour monitor.
>
> Will take a look, but I bet they don't look quite as nice as some of the
> colour pictures I've converted to the pluses ;-)
There are a couple of slideshows/animations around that work only on
green-screen CPCs and Pluses (usually in grey)...
Keith M. Lucas
In article <IQBSTIA3...@netcomuk.co.uk>,
Roland Perry <nos...@affordable.co.uk> wrote:
>It's very "logical". It's an arrangement that allows conversion from the
>32 different hardware colours (5 repeated) to the 27 displayable colours
>using the least possible number of ULA gates to do the work.
How did I know it would end up being something like this...
Andrew P. Cadley
On Fri, 14 Nov 1997, Kev Thacker wrote:
> On Thu, 13 Nov 1997 22:23:03 +0000, ric...@systemeD.u-net.comma
> (Richard Fairhurst) wrote:
>
> >Roland Perry <nos...@affordable.co.uk> wrote:
> >
> Thankyou to Mr. Cadley, he has told me of some of the really cool
> effects that can be done with the Plus.
>
And thanks to Kev for producing a plus emulator, I miss my machine dearly
while I'm a Uni. :-(
> He mentioned a way you can split the sprite in half vertically, and
> also it might be possible to split it horizontally too.
In fact, with the latest documentation on IM 2 and the ASIC emerging it
appears there may be tricks even I haven't tried.
I think my plus is gonna be in overdrive the chrimble :-)
AndyC
Marcus Durham
In article <srh28.28...@cam.ac.uk>, Sam Holloway <sr...@cam.ac.uk>
cheerily wrote:
[snip]
>(BTW, I read AA for years and - though I hate to say this - I don't remember
>Simon. Please could someone comment on why I missed him?)
[snip]
You can't of missed him. He's the scary hairy one* who wrote Bootracker.
* The other scary hairy one being Rod Lawton. Although it's never been
disproved that both are one and the same.
Lazy Bone
> I couldn't save these arc-files. They just showed up on the screen as
> weird text when I clicked on the links. I'm using Netscape 3.03 Gold.
>
> ----
> Ivar Fiske
Ivar,
It is possibly a bug in Netscape. They ARE there and they DO work on
the website - at least they do with MSIE and AWeb 2.
In MSIE, you can use a right mouse button to save a file, if you can
do that in Netscape, try that instead of just clicking on them.
Regards
Julian Cassin
Simon Matthews
Richard Fairhurst wrote:
>
> Simon Matthews <s.j.ma...@nospam.lhmc.ac.uk> wrote:
>
> > [AA pictures]
> > Me too. Unfortunately taken in Rob's flat at Plumstead in front of the
> > most hideous curtains you have ever seen. Oh, and on a bad hair day as
> > well.
>
> The infamous STS/Quantum article, I presume?
Why, yes!
--
+---------------------------------------+-------------------------------+
| Simon Matthews | Do you hear what I hear? |
| s.j.ma...@nospam.lhmc.ac.uk | Bittering distress, |
| Remove "nospam" to reply | Who decides what you express? |
| Spam will be returned in spades | "Eye" ....And Justice for All |
+---------------------------------------+-------------------------------+
| Fenster : I had some guy's fingers in my asshole tonight! |
| Hockney : Is it Friday already? |
| Fenster : F*ck you! I'll never shit right again. |
+-------------------------------------------------The Usual
Suspects----+
Sam Holloway
In article <1997111322...@p60.nas4.is2.u-net.net> ric...@systemeD.u-net.comma (Richard Fairhurst) writes:
>From: ric...@systemeD.u-net.comma (Richard Fairhurst)
>Subject: Re: Why 27 colors on the amstrad cpc ?
>Date: Thu, 13 Nov 1997 22:23:03 +0000
>Roland Perry <nos...@affordable.co.uk> wrote:
>> True. You can also change mode part way down as well.
>Or part way across if you're really clever, as Kevin will testify...
Or wherever you like, which is what the previous two messages have said
already. There was a cracking program (cracking as in good, not as in
listening to illegal things) in CPC Attack that did this. Remember CPC Attack,
Richard/Simon.
(BTW, I read AA for years and - though I hate to say this - I don't remember
Simon. Please could someone comment on why I missed him?)
Cheers,
Sam
----------------------------------------
The number you have dialled is imaginary
Please rotate your phone by pi/2 radians
and try again. Thankyou.
Sam Holloway sr...@cam.ac.uk
----------------------------------------
Aragorn!
It's not a Netscape bug, you have to have .arc defined in your mime types
otherwise Netscape just tried to view them by default.
Our Uni machines used to do the same with Arj files...
David
----------------------------------------------------------
| Life is what happens when you're making other plans |
| |
| Aragorn! ,,, email: bsc...@dcs.napier.ac.uk |
| (o o) http://www.dcs.napier.ac.uk/~bsc4074 |
----------ooO-(_)-Ooo-------------------------------------
Aragorn!
On Thu, 13 Nov 1997, Richard Fairhurst wrote:
> Roland Perry <nos...@affordable.co.uk> wrote:
>
> > True. You can also change mode part way down as well.
>
> Or part way across if you're really clever, as Kevin will testify...
>
I remember a type-in in AA 14 or 15 which changed modes/colours on the fly.
If i remember correctly, it split the display into 4 areas, all with
different colour palettes just to demonstrate the effect.
It wasn't glitch free but back in '85 who cared?
Sam Holloway
>Marcus E. Durham posted recently:
> Sam Holloway <sr...@cam.ac.uk> cheerily wrote:
>[snip]
>>(BTW, I read AA for years and - though I hate to say this - I don't remember
>>Simon. Please could someone comment on why I missed him?)
>[snip]
>You can't of missed him. He's the scary hairy one* who wrote Bootracker.
>* The other scary hairy one being Rod Lawton. Although it's never been
>disproved that both are one and the same.
I remember Rod Lawton. Everyone used to take the piece (French pronunciation)
out of his personal hygine. :-) Where are they now? What about the OLD
stalwarts like Pat McDonald? Speak up, you ex-AA staff...
Sam Holloway
From Richard Fairhurst:
>Sam Holloway <sr...@cam.ac.uk> wrote:
>> There was a cracking program (cracking as in good, not as in
>> listening to illegal things) in CPC Attack that did this (change modes).
>Er, are you sure? I can't find one in any of my back issues.
Hmmm. Actually, I think it was raster ops. to do many colours in Mode 1/2. My
memory's not what it used to be. (16MB as opposed to 128K :-))
>> Remember CPC Attack, Richard/Simon?
>Indeed... I used to write for it. Best career decision of my life (not
>that there's an awful lot of competition) was rejecting CPC Attack!'s
>offer of lots of monthly cash to write exclusively for them. This was
>about two months before it folded... :-)
I've still got them all. Wish I could say the same for the masses of other CPC
stuff I sold six or so years back :,-(
>A related(-ish) query: setting bits 0 and 1 of the VGA control register
>("MODE 3", in other words) selects a 160x200 mode with just four
>colours. I seem to remember hearing of an ACU listing which employed
>this mode to some gainful end. Any idea what that might be?
I remember a listing in ACU that extended the number of rows on the screen to
something like 31/32 - must have been in a 1987/88 issue or something like
that. If my memory (see above) serves me rightly, that did something involving
the extra MODE 3. Then again, maybe not. Just thought I'd mention this in case
someone typed it in. It was rather clever...
Barry Rodewald
Aragorn! wrote:
> On 14 Nov 1997, Lazy Bone wrote:
>
> >
> > It is possibly a bug in Netscape. They ARE there and they DO work on
> > the website - at least they do with MSIE and AWeb 2.
> >
> > In MSIE, you can use a right mouse button to save a file, if you can
> > do that in Netscape, try that instead of just clicking on them.
> >
> It's not a Netscape bug, you have to have .arc defined in your mime types
> otherwise Netscape just tried to view them by default.
>
No, it is not a bug, all you should have to do is either right-click on the
link and select Save Link as... or hold shift and click the link.
I am assuming that these are links to these 'arc-files' on a web page
somewhere (I haven't seen the original post for this problem).
Hope this helps,
Barry Rodewald.
David Long
On Mon, 17 Nov 1997, Richard Fairhurst wrote:
> A related(-ish) query: setting bits 0 and 1 of the VGA control register
> ("MODE 3", in other words) selects a 160x200 mode with just four
> colours. I seem to remember hearing of an ACU listing which employed
> this mode to some gainful end. Any idea what that might be?
This only takes up 8K screen RAM, due to it being MODE 0 with half the
colour depth, giving you 8K extra memory to play around with. IIRC the
main point of the program was that screendump files only took 9K instead
of 17K.
Any idea what reprogramming the CRTC with lines > 25 does in this mode?
Does it just do the standard repeating effect or does it give you overscan
with no messing about? Although 4-colour low-res overscan is hardly going
to look impressive...
--
David Long [D.C....@warwick.ac.uk] 1st year CS student at Warwick University
Room 101 JM4, Jack Martin Residences, University of Warwick, Coventry, CV4 7AL
Simon Forrester
> >Marcus E. Durham posted recently:
>
> > Sam Holloway <sr...@cam.ac.uk> cheerily wrote:
> >[snip]
> >>(BTW, I read AA for years and - though I hate to say this - I don't
remember
> >>Simon. Please could someone comment on why I missed him?)
> >[snip]
>
> >You can't of missed him. He's the scary hairy one* who wrote Bootracker.
>
> >* The other scary hairy one being Rod Lawton. Although it's never been
> >disproved that both are one and the same.
>
> I remember Rod Lawton. Everyone used to take the piece (French pronunciation)
> out of his personal hygine. :-) Where are they now? What about the OLD
> stalwarts like Pat McDonald? Speak up, you ex-AA staff...
Well, I came along quite late, y'see. Issue, um, 89 or something like
that. I bumped into Pat recently - he popped into the pub to see Trenton
and Bob. Angela's working on a 'where are they now' piece, and when she
sends me a list I'll explain who's where and how. She may have already,
but I got 116 emails this morning, so it takes a while to read them.
--
Simon Forrester http://www.futurenet.com sforr...@futurenet.com
-SFNet- -cult tv- -MacWeb-
Trek, B5, Dwarf, For the cooler kind THE independent UK
and loads more of couch potato Mac resource
Simon Forrester
> Future is sometimes good on things like that (though whatever happened to
> the CPC's Simon Stansfield wouldn't let any one have?). I got a black Future
> mug a few years back, broke the handle and now use it as a pen holder.
I think they're in the big Future basement along with the Speccies and C64s.
Simon Forrester
In article <01bcf013$de984fe0$fa31...@euwyfw10209.WYF.EU.BP.COM>,
"Matthew Breckon" <BreckoMJ.i_don...@bp.com> wrote:
I won money every month!
Andrew P. Cadley
On Mon, 17 Nov 1997, Richard Fairhurst wrote:
> Sam Holloway <sr...@cam.ac.uk> wrote:
>
> > Richard Fairhurst wrote:
> >
> > >Roland Perry <nos...@affordable.co.uk> wrote:
> > >> True. You can also change mode part way down as well.
> > >Or part way across if you're really clever, as Kevin will testify...
> > Or wherever you like, which is what the previous two messages have said
> > already.
> No: you cannot usually change _mode_ halfway through a line. Colours, no
> problem.
Well if you brain is a big as Kevin's you can.
AndyC
Brian Watson
In article <64sebq$cu0$1...@morse.news.easynet.net>
cli...@amstrad.com "Cliff Lawson" writes:
> Richard Fairhurst wrote in message
> <199711172...@p3.nas4.is2.u-net.net>...
> >A related(-ish) query: setting bits 0 and 1 of the VGA control register
> >("MODE 3", in other words) selects a 160x200 mode with just four
> >colours. I seem to remember hearing of an ACU listing which employed
> >this mode to some gainful end. Any idea what that might be?
>
>
> Blush, I wrote that article but more than that I cannot remember ('least I
> think I wrote it! Blimey, isn't memory (or rather the lack of it) a funny
> thing?)
>
> Ah yes now that I think about it some more I think I remember the reason for
> doing it - it freed up 8K of video memory though I presume that must have
> been every other byte which wouldn't have been THAT useful!
>
> Cliff
I've got all the ACUs, so could look this up if it helps...?
--
Brian Watson
:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
:: Protext Robot Software Pipeline Parados 8BIT IEBA WACCI Publicity ::
:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
Andrew P. Cadley
On Mon, 17 Nov 1997, Sam Holloway wrote:
> From Richard Fairhurst:
>
> >Sam Holloway <sr...@cam.ac.uk> wrote:
> >A related(-ish) query: setting bits 0 and 1 of the VGA control register
> >("MODE 3", in other words) selects a 160x200 mode with just four
> >colours. I seem to remember hearing of an ACU listing which employed
> >this mode to some gainful end. Any idea what that might be?
>
> I remember a listing in ACU that extended the number of rows on the screen to
> something like 31/32 - must have been in a 1987/88 issue or something like
> that. If my memory (see above) serves me rightly, that did something involving
> the extra MODE 3. Then again, maybe not. Just thought I'd mention this in case
> someone typed it in. It was rather clever...
Well, you can use MODE 3 to store two screens in 16K, since only four of
the bits are decoded. That way you can switch between them by rotating
the bytes.
'course you have to put up with 4 colour low-res screens :-(
AndyC
Cliff Lawson
>("MODE 3", in other words) selects a 160x200 mode with just four
>colours. I seem to remember hearing of an ACU listing which employed
>this mode to some gainful end. Any idea what that might be?
Ivar Fiske
Cliff Lawson wrote:
> Blush, I wrote that article but more than that I cannot remember ('least I
> think I wrote it! Blimey, isn't memory (or rather the lack of it) a funny
> thing?)
>
> Ah yes now that I think about it some more I think I remember the reason for
> doing it - it freed up 8K of video memory though I presume that must have
> been every other byte which wouldn't have been THAT useful!
Yes, I remember that issue of ACU, the only one I never got my hands on.
It didn't reach Norway. January 1986 if my memory serves me right.
---
Ivar Fiske
Kev Thacker
I've got a lot back home and I will collect them at Xmas including
some other documents about the CPC hw.
One of the articles which increased the number of vertical lines used
vertical splitting (the demo technique where you can change the screen
start address each line if you want).
I was impressed when I typed it in and ran it.
Kev
Richard Fairhurst
Kev Thacker <ktha...@krisalis.co.uk> wrote:
> One of the articles which increased the number of vertical lines used
> vertical splitting (the demo technique where you can change the screen
> start address each line if you want).
>
> I was impressed when I typed it in and ran it.
IIRC, Alan Scully ripped that one off for Pagemaker Deluxe. Er, not that
Mr Scully made a habit of ripping code.
Simon Matthews
Richard Fairhurst wrote:
>
> Kev Thacker <ktha...@krisalis.co.uk> wrote:
>
> > One of the articles which increased the number of vertical lines used
> > vertical splitting (the demo technique where you can change the screen
> > start address each line if you want).
> >
> > I was impressed when I typed it in and ran it.
>
> IIRC, Alan Scully ripped that one off for Pagemaker Deluxe. Er, not that
> Mr Scully made a habit of ripping code.
Allegedly.
Kevin, I'd be really interested to see any docs you've got on hw
splitting, 'cos it's driving me round the twist at the moment.
Simon
Angela Cook
Simon Forrester wrote in message ...
>In article <01bcf013$de984fe0$fa31...@euwyfw10209.WYF.EU.BP.COM>,
>"Matthew Breckon" <BreckoMJ.i_don...@bp.com> wrote:
>
>> I won a tenner for writing the solution to Lopears (great game ;-)
>> Apart from that never got anything else in it's hallowed pages, sniff
sniff
>> ;-)
>>
>> Matt
>
>I won money every month!
Note he doesn't use the word "earn"....
- Angela
Kev Thacker
I've got some ideas that I hope will work, plus some nice ideas for
the CPC+.
I'll e-mail you them next week because I don't have them on my
computer at work.
I believe I know how to make it work, although it involves very
accurate timing, and this is a problem.
I've got to work out how to sync exactly with the start of the vsync
signal. (unfortunatly the current method has an accuracy of 8 clock
cycles which is not accurate enough).
Kev
Angela Cook
Simon Forrester wrote in message ...
>In article <654cet$25l$3...@nclient3-gui.server.virgin.net>, "Angela Cook"
>Now hold on there - during my first few months at AA, did you notice my
>name on almost every page? Bloody ridiculous, if you ask me. I was doing
>35,000 words a month, and it hurt. So there. :P
Ahhhh, you poor thing. Actually, I did start taking notice of AA shortly
after you arrived. Little did I know I would end up writing or it. We never
can tell these things. If we could, I would have given Who Said That a
better review and Radical (which I now run) might have sold more of them. I
suppose I shall have to make my fortune elsewhere.
- Angela
Simon Forrester
In article <654cet$25l$3...@nclient3-gui.server.virgin.net>, "Angela Cook"
<angela...@virgin.net> wrote:
> Simon Forrester wrote in message ...
> >In article <01bcf013$de984fe0$fa31...@euwyfw10209.WYF.EU.BP.COM>,
> >"Matthew Breckon" <BreckoMJ.i_don...@bp.com> wrote:
> >
> >> I won a tenner for writing the solution to Lopears (great game ;-)
> >> Apart from that never got anything else in it's hallowed pages, sniff
> sniff
> >> ;-)
> >>
> >> Matt
> >
> >I won money every month!
>
> Note he doesn't use the word "earn"....
>
> - Angela
Now hold on there - during my first few months at AA, did you notice my
name on almost every page? Bloody ridiculous, if you ask me. I was doing
35,000 words a month, and it hurt. So there. :P
--