Search found 477 matches

by IanS
Fri May 12, 2017 11:25 am
Forum: hardware
Topic: VIDC enhancer pins on the A540 : question
Replies: 12
Views: 420

Re: VIDC enhancer pins on the A540 : question

The qube server page has been shown to be wrong before - http://stardot.org.uk/forums/viewtopic.php?f=16&t=12772&p=167834#p167834 The unfiltered output from the arc was probably never intended to drive external equipment (speakers, headphones etc.), so buffering the output to drive external ...
by IanS
Fri May 12, 2017 10:52 am
Forum: hardware
Topic: VIDC enhancer pins on the A540 : question
Replies: 12
Views: 420

Re: VIDC enhancer pins on the A540 : question

The extra op-amp is probably a way of isolating the output from the Arc, so you can't do damage to the on-board components. It may not be amplifying the signal at all, it may have a gain of 1.

https://en.wikipedia.org/wiki/Buffer_amplifier
by IanS
Fri May 12, 2017 10:19 am
Forum: hardware
Topic: VIDC enhancer pins on the A540 : question
Replies: 12
Views: 420

Re: VIDC enhancer pins on the A540 : question

Looks like it's connected to LK9
a540_links.PNG

Which is unfiltered audio.
a540_lk9.PNG
(21.26 KiB) Not downloaded yet


So my guess is it's a buffered unfiltered audio out
by IanS
Wed May 10, 2017 8:58 pm
Forum: hardware
Topic: Burning a RISC OS 2.01 EPROM
Replies: 7
Views: 360

Re: Burning a RISC OS 2.01 EPROM

If it doesn't work, let me know and I'll dig out some RISC OS 2 ROMs that you can have... Thanks Rob. It needs to be 2.01 for the 540 as I understand? I have found some 2.0 ROMs... do you think they'd work...? 2.01 added ARM 3 support, did it also add support for different VIDC clocks? My A540 was ...
by IanS
Wed May 10, 2017 8:17 pm
Forum: past events & exhibitions
Topic: May 12th-14th 2017 Cambridge ABUG (FULL) & Acorn World event at CCfCH
Replies: 190
Views: 12509

Re: May 12th-14th 2017 Cambridge ABUG (FULL) & Acorn World event at CCfCH

Something has come up that means, sadly, I am now not able to attend. I am completely gutted about this - I haven't missed an ABUG meeting since I joined StarDot. That's a shame, who is going to make all the noise now :D (I was looking forward to seeing/hearing the new noise maker) See you at the n...
by IanS
Mon May 08, 2017 7:21 pm
Forum: past events & exhibitions
Topic: May 12th-14th 2017 Cambridge ABUG (FULL) & Acorn World event at CCfCH
Replies: 190
Views: 12509

Re: May 12th-14th 2017 Cambridge ABUG (FULL) & Acorn World event at CCfCH

Yes we can stay late Friday Saturday as per last year! Parking is available but limited spaces. There would have been more if the garage next door hadn't put a chain across their parking bays. When I spoke to Jason F about it he said he forgot to ask them to leave it open. If you are in contact wit...
by IanS
Sun May 07, 2017 11:22 pm
Forum: general
Topic: Mike Harrison YouTube vid on Beeb
Replies: 2
Views: 379

Re: Mike Harrison YouTube vid on Beeb

Interesting, I've watched mike's youtube channel, and I've seen his name on many Podules and Acorn ad-ons, but never made the connection. Small world.
by IanS
Sat Apr 29, 2017 4:15 pm
Forum: hardware
Topic: Repairing a broken Archimedes A3000 ... Update 14.05.17 - mouse progress - the mouse fully works too! I think, it's done
Replies: 159
Views: 5727

Re: Repairing a broken Archimedes A3000 ... Update 29.04.17 - 4MB memory and still a CMOS issue with two AA cells.

Looks like the picture on the qubeserver web page is wrong. It also doesn't show D1 fitted, so I suspect the battery in that picture is doing nothing useful.
by IanS
Sat Apr 29, 2017 4:04 pm
Forum: hardware
Topic: Repairing a broken Archimedes A3000 ... Update 14.05.17 - mouse progress - the mouse fully works too! I think, it's done
Replies: 159
Views: 5727

Re: Repairing a broken Archimedes A3000 ... Update 29.04.17 - 4MB memory and still a CMOS issue with two AA cells.

It does look like your polarity is wrong. Look at the Alt mouse cpnnector location at the edge of the board. Most of the PCB pads are round, one of them is square. The square one is Pin 1. For the battery connector, LK5, one of the pads is square, that is also pin 1. Pin 1 on LK5, according to the c...
by IanS
Wed Apr 19, 2017 6:15 pm
Forum: hardware
Topic: Repairing a broken Archimedes A3000 ... Update 14.05.17 - mouse progress - the mouse fully works too! I think, it's done
Replies: 159
Views: 5727

Re: Repairing a broken Archimedes A3000 ... Update 16.04.17 ... almost all keys work, but pin15 keys don't ...

Now the keyboard is working, have you done a delete power-on? Hold delete whilst powering on, hold it until you see the RISC OS banner.
by IanS
Mon Apr 17, 2017 6:56 pm
Forum: hardware
Topic: BBC to VGA connector
Replies: 20
Views: 1127

Re: BBC to VGA connector

Thanks @KenLowe. I have access to 3 TVs with SCART connectors here in Bulgaria. I wonder if the old PAL/SECAM distinction is still, somehow preserved with flat-screen TVs? http://stardot.org.uk/forums/viewtopic.php?f=41&t=12870&p=165893#p165893 With RGB inputs on a SCART socket, there is NO...
by IanS
Fri Apr 14, 2017 9:56 pm
Forum: other vintage computer hardware, software and games
Topic: IBM PC XT meets the 21st Century!
Replies: 16
Views: 971

Re: IBM PC XT meets the 21st Century!

jms2 wrote:How is the A4000 running Windows?

PC podule? - http://chrisacorns.computinghistory.org ... odule.html
by IanS
Fri Apr 14, 2017 9:52 pm
Forum: other vintage computer hardware, software and games
Topic: Superbrain power supplyhi
Replies: 53
Views: 1587

Re: Superbrain power supplyhi

jonb wrote:Really?

See the discussion on another thread about power supplies with isolated outputs - viewtopic.php?f=3&t=12883&p=166072#p166102
by IanS
Fri Apr 14, 2017 8:49 pm
Forum: other vintage computer hardware, software and games
Topic: IBM PC XT meets the 21st Century!
Replies: 16
Views: 971

Re: IBM PC XT meets the 21st Century!

It also had an RS sticker on it which possibly means it was owned by them once ... 8) Probably not - http://webcache.googleusercontent.com/search?q=cache:LjYXh1vD1LUJ:uk.rs-online.com/web/p/pre-printed-adhesive-magnetic-labels/0497202/+&cd=1&hl=en&ct=clnk&gl=uk (RS is down for maint...
by IanS
Fri Apr 14, 2017 8:36 pm
Forum: other vintage computer hardware, software and games
Topic: Superbrain power supplyhi
Replies: 53
Views: 1587

Re: Superbrain power supplyhi

OK, measurements. Common - +12v = 11.73v Common - +5v = 4.85v Common to -12v - nothing Common to -5v - nothing - 5v to +5v - 5v -12v - +12v - 12v So it looks like this PSU doesn't give any genuine negative voltages. It's a nice PSU, but it won't run the 4116 RAM chips. I'll just have to be patient ...
by IanS
Thu Apr 13, 2017 9:33 pm
Forum: hardware
Topic: Acorn Archimedes Hard Drive missing
Replies: 9
Views: 427

Re: Acorn Archimedes Hard Drive missing

Its a 400, i don't have an apps icon. Just floppy, palette and tasks Which version of RISC OS is fitted? (is the icon at the far right an Acorn (RISC OS 3) or the Archimedes logo (RISC OS 2)). Sounds like RISC OS 2. Has it got any podules fitted? (Type *PODULES after pressing F12, can't remember if...
by IanS
Thu Apr 13, 2017 9:29 pm
Forum: hardware
Topic: A3000 OS EPROMs
Replies: 7
Views: 448

Re: A3000 OS EPROMs

It's for an A3000. Sorry, I mentioned the machine in the title but not the body of the post. In that case, will need to check the circuit diagram. The problem with EPROM compared to ROMs of same physical size is that EPROMs require one of the pins for programming, and so have a slightly different p...
by IanS
Wed Apr 12, 2017 11:13 pm
Forum: hardware
Topic: A3000 OS EPROMs
Replies: 7
Views: 448

Re: A3000 OS EPROMs

I guess something like a 27c040 would work (OTP). It's also possible with Flash chips (somthing like I did with 28sf040 or 39sf040 etc. http://stardot.org.uk/forums/viewtopic.php?f=16&t=12252&p=156210#p156245 ). You will need to be a bit creative with the link settings with Flash as the A18 ...
by IanS
Wed Apr 12, 2017 4:38 pm
Forum: hardware
Topic: System 5 PSU questions
Replies: 9
Views: 534

Re: System 5 PSU questions

Pins 10-13 could be remote sense connections, but it would be odd to have sense connections for both rails.
https://en.wikipedia.org/wiki/Sense_(electronics)
by IanS
Mon Apr 10, 2017 7:46 pm
Forum: general
Topic: Today I received.....
Replies: 4319
Views: 252016

Re: Today I received.....

"Expandor Systems" according to the back. Not seen these before either. Thoughts? Hi, I also have a rare rom board which look a bit like yours but this rom board is for the Atom... Greetings, Wim... :-) That's guaranteed to have caught someone out at some point. The sockets are all facing...
by IanS
Sun Apr 09, 2017 5:14 pm
Forum: other vintage computer hardware, software and games
Topic: Superbrain power supplyhi
Replies: 53
Views: 1587

Re: Superbrain power supplyhi

I'd say that the PSU is almost certainly OK. In a simple flyback design like that one where only one rail is regulated, the secondary outputs (like +21V) won't be able to deliver their rated current until there's enough load on the main output (+5V here). I'm guessing the monitor is powered from +2...
by IanS
Sun Apr 09, 2017 4:31 pm
Forum: other vintage computer hardware, software and games
Topic: Superbrain power supplyhi
Replies: 53
Views: 1587

Re: Superbrain power supplyhi

jonb wrote:The first problem is the power supply. It had a burned out section with a hole in the PCB (after cleaning) the size of a 20p piece. I cleaned it and rebuilt the circuit using a tiny piece of veroboard.

Knowing which bit burnt out might give a clue.
by IanS
Thu Mar 30, 2017 9:26 pm
Forum: acorn atom
Topic: Pi-Tube Atom VDU: circles
Replies: 24
Views: 1249

Re: Pi-Tube Atom VDU: cirles

I can't figure out why the distance between the circles is not linear. Any clues? Do the circles get drawn in the right order, are any drawn our of sequence because a value is overflowing? At least one will be drawn in black, so not visible. If you draw them all in the same colour, does it look any...
by IanS
Mon Mar 27, 2017 11:28 pm
Forum: hardware
Topic: Resurrecting an early A3010
Replies: 18
Views: 886

Re: Resurrecting an early A3010

None of the pictures you posted work. Do they work for anyone else?

Just upload them to the site as attachments, no need to host them elsewhere.
by IanS
Sat Mar 18, 2017 4:23 pm
Forum: general
Topic: Today I received.....
Replies: 4319
Views: 252016

Re: Today I received.....

IanS wrote:Untested PCB. Just need to order a few more parts to build it up.
_20170313_173053.JPG

Tested.
IMG_20170318_155505007.jpg

IMG_20170318_155544769.jpg
by IanS
Thu Mar 16, 2017 10:19 pm
Forum: past events & exhibitions
Topic: ABug Leicestershire Nov 2017 - Venue & Date confirmation
Replies: 53
Views: 3574

Re: ABUG EAST MIDLANDS (Winter Warmer) 17-19 November 2017 (Leicestershire)

lazarusr wrote:I think we need to have a rule that people must divide their time between both rooms regardless of where their kit is based.

:o :o :o Really?

How do you plan to enfore this rule?
by IanS
Mon Mar 13, 2017 10:22 pm
Forum: general
Topic: Today I received.....
Replies: 4319
Views: 252016

Re: Today I received.....

Untested PCB. Just need to order a few more parts to build it up.
_20170313_173053.JPG
by IanS
Sat Mar 11, 2017 11:03 pm
Forum: hardware
Topic: Replacement 6522
Replies: 6
Views: 461

Re: Replacement 6522

daveejhitchins wrote:Parts: UM6502CE, GAL22V10D, GAL16V8D, AT28C256, AT28C256, AS6C62256A, TC514400AZ, WD1772, TMS27C512, R6522, TMS27C512, AT28C256, AT28C256

I'm guessing you have some AT28C256's, but I can't be sure.
by IanS
Wed Mar 01, 2017 7:01 pm
Forum: general
Topic: Science Museum yeast control system
Replies: 13
Views: 645

Re: Science Museum yeast control system

BigEd wrote:Computers in Control - I don't even remember that one!

There are low quality versions of the episodes around.
by IanS
Wed Feb 22, 2017 7:26 pm
Forum: off-topic
Topic: PayPal fees, WTF?
Replies: 14
Views: 1327

Re: PayPal fees, WTF?

Anyone tried Paym, I've had it set up for a couple of years, just never found anyone else with it.

http://www.paym.co.uk/

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