On Mar 6, 1:01*pm, Bob Eager wrote:

7. It's not a Start button. It does not have Start on it. It doesn't
start the system.

Great big "Start" tooltip appears when you hover it.

Andy Dingley wrote:
On Mar 4, 10:09 pm, Bob Eager wrote:
Since the Raspberry Pi will be with us soon-ish (well, about six weeks I
am told, for mine) does anyone have any interesting ideas about what they
might do with it/them?

Laser cutting machine controller. Interprets G-code and also runs the
user interface to set the machine up.


that is a first class idea...

can it control stepper motors directly tho?

and detect optical limit switches?


Hopefully the rPi's DSI interface will also be available, so that I
can hang cheap S/H laptop screens onto it, so won't need a separate
monitor.


--
To people who know nothing, anything is possible.
To people who know too much, it is a sad fact
that they know how little is really possible -
and how hard it is to achieve it.

On Tue, 13 Mar 2012 15:23:08 -0700 (PDT), Andy Dingley
wrote:

On Mar 5, 12:39*pm, Bernard Peek wrote:

But could you spare a couple of hours to bring an existing teacher up to
speed?

I'd love to. Now how do I explain this to friends who are being laid
off from our local university, where they were already doing just that
as their full-time job? This "rework ICT" initiative sounds great at
first, except that it also seems to be being used as an excuse to dump
its teaching from state-funded schools and onto the voluntary sector.

This is happening all over the place. It's called the "Big Society".
--
(\__/) M.
(='.'=) If a man stands in a forest and no woman is around
(")_(") is he still wrong?

On Mon, 12 Mar 2012 12:36:08 GMT, lid
(Windmill) wrote:

Tim Streater writes:

In article ,
John Rumm wrote:

On 11/03/2012 05:26, Windmill wrote:
John writes:

On 10/03/2012 17:48, Jules Richardson wrote:
On Sat, 10 Mar 2012 13:33:46 +0000, John Rumm wrote:
;-) Rather like talking with IMB mid range / mainframe types who seem
convinced that Assembler (note the capital A!) can only be known to
hallowed IBM programmers, and can't seem to get their heads round the
fact that every processor has a low level assembly language...

Every? Depends on the definition of assembly language, I suppose - is it
the binary opcodes which form CPU instructions, or is it the human-
readable mnemonics which correspond to those opcodes?

The latter...

I usually think of assembly language as the latter (that being what
people program at the low level using), but I suppose it's entirely
possible to have a CPU where there are no official published mnemonics
and instead things are documented in a more long-winded "binary opcode xx
performs operation yy" form.

I find it hard to imaging how you would document a processor instruction
set without in the process creating its assembly language as a result...
I suppose you could describe every instruction longhand, but I can't
imagine it would be long before some one comes along and creates
mnemonics for each.

ISTR some sort of 8 bit CPU (? Z80 ?) whose documentation included a
description in BNF.

Yup, used to be quite common, but does not seem to get much of an outing
these days. Not sure if I ever had the official Zilog books on the Z80,
although I have got Zaks, and that may well "borrow" the official
language description as many books of its day did.

BNF is a bit turgid to read. May as well use mnemonics.

I suspect it's because of a limited capacity to keep large amounts of
stuff in mind, but I've always preferred high-density information to
the wordy stuff; BNF isn't an easy read, but in younger days I could
puzzle my way through it with some effort.

BNF can be very useful if you are writing a parser.
--
(\__/) M.
(='.'=) If a man stands in a forest and no woman is around
(")_(") is he still wrong?

On Tue, 13 Mar 2012 04:57:46 GMT, lid
(Windmill) wrote:

Adrian C writes:

Probably pales into insignificance compared to a PDP8, but I did once
throw a few bits of 6800 series around a 6809, 74 logic and static ram
chips, wirewrap the whole thing on a eurocard, burn an eprom and get a
monitor going. Then I wrote a terminal program on my BBC micro to talk
to it, and completely missed the objectives of my final year college
project I was building it for.

Now I've got a few 486SX chips floating around the workshop. Maybe I
should wirewrap one of those up into something that runs. Or maybe not.

Got a bad bad past history of building and assembling computers and then
finding absolutely no use for them once running. Sat in this room with,
oh (quick count), 10 of them around me.

For me nowadays, it's a matter of collecting old PCs thrown out onto
the street (by people who don't want to pay the Council to pick them
up, maybe) and occasionally resuscitating one to run something
diffferent like W95, OpenBSD, or a largely home-grown Linux version.

I've got several like this, all missing hard disks.
--
(\__/) M.
(='.'=) If a man stands in a forest and no woman is around
(")_(") is he still wrong?

On 14/03/2012 09:11, Mark wrote:
On Mon, 12 Mar 2012 12:36:08 GMT, lid
(Windmill) wrote:

Tim writes:

In articleOvGdna0mRsnxasHSnZ2dnUVZ8gOdnZ2d@brightvie w.co.uk,
John wrote:

On 11/03/2012 05:26, Windmill wrote:
John writes:

On 10/03/2012 17:48, Jules Richardson wrote:
On Sat, 10 Mar 2012 13:33:46 +0000, John Rumm wrote:
;-) Rather like talking with IMB mid range / mainframe types who seem
convinced that Assembler (note the capital A!) can only be known to
hallowed IBM programmers, and can't seem to get their heads round the
fact that every processor has a low level assembly language...

Every? Depends on the definition of assembly language, I suppose - is it
the binary opcodes which form CPU instructions, or is it the human-
readable mnemonics which correspond to those opcodes?

The latter...

I usually think of assembly language as the latter (that being what
people program at the low level using), but I suppose it's entirely
possible to have a CPU where there are no official published mnemonics
and instead things are documented in a more long-winded "binary opcode xx
performs operation yy" form.

I find it hard to imaging how you would document a processor instruction
set without in the process creating its assembly language as a result...
I suppose you could describe every instruction longhand, but I can't
imagine it would be long before some one comes along and creates
mnemonics for each.

ISTR some sort of 8 bit CPU (? Z80 ?) whose documentation included a
description in BNF.

Yup, used to be quite common, but does not seem to get much of an outing
these days. Not sure if I ever had the official Zilog books on the Z80,
although I have got Zaks, and that may well "borrow" the official
language description as many books of its day did.

BNF is a bit turgid to read. May as well use mnemonics.

I suspect it's because of a limited capacity to keep large amounts of
stuff in mind, but I've always preferred high-density information to
the wordy stuff; BNF isn't an easy read, but in younger days I could
puzzle my way through it with some effort.

BNF can be very useful if you are writing a parser.

Yup, formal language specs are probably what its best at... limited
audience perhaps though.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On 14/03/2012 09:13, Mark wrote:
On Tue, 13 Mar 2012 04:57:46 GMT, lid
(Windmill) wrote:

Adrian writes:

Probably pales into insignificance compared to a PDP8, but I did once
throw a few bits of 6800 series around a 6809, 74 logic and static ram
chips, wirewrap the whole thing on a eurocard, burn an eprom and get a
monitor going. Then I wrote a terminal program on my BBC micro to talk
to it, and completely missed the objectives of my final year college
project I was building it for.

Now I've got a few 486SX chips floating around the workshop. Maybe I
should wirewrap one of those up into something that runs. Or maybe not.

Got a bad bad past history of building and assembling computers and then
finding absolutely no use for them once running. Sat in this room with,
oh (quick count), 10 of them around me.

For me nowadays, it's a matter of collecting old PCs thrown out onto
the street (by people who don't want to pay the Council to pick them
up, maybe) and occasionally resuscitating one to run something
diffferent like W95, OpenBSD, or a largely home-grown Linux version.

I've got several like this, all missing hard disks.

Makes a change... the number of people who lob out the old machine
complete with all their personal files and information intact is
frightening!

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

Mark writes:

This is happening all over the place. It's called the "Big Society".

Mr. Big runs society.

--
Windmill, Use t m i l l
J.R.R. Tolkien:- @ O n e t e l . c o m
All that is gold does not glister / Not all who wander are lost

"Tim Streater" wrote in message
...
In article om,
"brass monkey" wrote:

"Tim Streater" wrote in message
...
In article ,
"tim...." wrote:

"BartC" wrote in message
...


"Bob Eager" wrote in message
...
Since the Raspberry Pi will be with us soon-ish (well, about six
weeks I
am told, for mine) does anyone have any interesting ideas about
what they
might do with it/them?

I'm not quite sure what the purpose of this machine is. Low cost?
Once you've added a monitor, keyboard, mouse, memory (and a PSU?),
it won't be far from the cost of a netbook. (Edit: just seen that it
plugs into a TV. Still, you need a spare TV...)

and who (families) doesn't have a spare TV?

Keyboard 9.99, mouse 5.99 memory 9.99, total cost 50 quid

How are you proposing to add memory?

He presumably means an SD card.

Thass not memory in this context, though, is it?

I thought that was the memory option that it had.

If you can't add it any other way, then you can't add the cost of doing so
to the purchase price, can you?

If he means SSD equivalent he shoud say so.

so I didn't neeed to.

tim

"Mark" wrote in message
...
On Sun, 11 Mar 2012 09:42:23 -0000, "tim...."
wrote:


"BartC" wrote in message
...


"Bob Eager" wrote in message
...
Since the Raspberry Pi will be with us soon-ish (well, about six weeks
I
am told, for mine) does anyone have any interesting ideas about what
they
might do with it/them?

I'm not quite sure what the purpose of this machine is. Low cost? Once
you've added a monitor, keyboard, mouse, memory (and a PSU?), it won't
be
far from the cost of a netbook. (Edit: just seen that it plugs into a
TV.
Still, you need a spare TV...)

and who (families) doesn't have a spare TV?

We don't. Got rid of them as they take up too much room.

So you don't have one TV per house occupant so that everyone can watch their
own choice? (Wars have started for less)

tim

On Mar 14, 1:49*am, The Natural Philosopher
wrote:
Andy Dingley wrote:

Laser cutting machine controller. Interprets G-code and also runs the
user interface to set the machine up.

that is a first class idea...

can it control stepper motors directly tho?

A project called GRBBL already does this on the Arduino, although the
Arduino is creaking under the load and isn't running a user interface
at the same time.

For CNC mills (less so for lasers) the steppers are controlled by a
stepper drive module, like a Gecko. These take a simple control
interface of "num steps / direction" and also a configurable setup for
fastest speed, acceleration rates and current limits. This makes the
control task simpler, as the controller doesn't need to generate the
motor pulses. It also allows the rather significant (for mills anyway)
feature of current and maybe temperature control of the motors. You
can't do this from a single controller as there just isn't enough IO
to go round. You could of course build your own stepper controllers,
with their own embedded controllers, but the commercial ones are cheap
enough.