Search found 6393 matches

by hoglet
Sun Feb 24, 2013 10:18 am
Forum: general
Topic: Today I received.....
Replies: 4225
Views: 225827

Re: Today I recieved.....

Some ingredients for future projects....

IMG_0109.JPG
(552.63 KiB) Downloaded 238 times


IMG_0112.JPG
(479.22 KiB) Downloaded 238 times


:D :D :D
by hoglet
Wed Feb 20, 2013 7:25 am
Forum: hardware
Topic: RS423 upgrade for the Slogger Plus 2
Replies: 62
Views: 5264

Re: RS423 upgrade for the Slogger Plus 2

That will teach me to just look at the pictures :oops: :oops: :oops: :oops:
by hoglet
Tue Feb 19, 2013 11:15 pm
Forum: hardware
Topic: RS423 upgrade for the Slogger Plus 2
Replies: 62
Views: 5264

Re: RS423 upgrade for the Slogger Plus 2

Isn't pin 6 of the LS00 (an output) still causing a problem because it's going to be fighting with what ever is driving RDWR on the other side of pin 3 of the connector.

I think you need two additional cuts and a wire link to isolate pin 6.

Dave
by hoglet
Fri Feb 15, 2013 7:18 pm
Forum: for sale / freebies
Topic: FS: FIT, PET & Buffer (BBC Testing eqpmt) NOW SOLD
Replies: 4
Views: 494

Re: FS: FIT, PET & Buffer (BBC Testing eqpmt) NOW SOLD

... and the other half has gone on another 19" LCD TV (there's a particular make I'm buying which work well with Beebs, so are ideal for retro events). I'm up to 7 of these Tellys now, but I've been outbid on the last couple that have appeared ... boo! Would you mind saying what model this is?
by hoglet
Mon Feb 11, 2013 10:30 pm
Forum: hardware
Topic: RS423 upgrade for the Slogger Plus 2
Replies: 62
Views: 5264

Re: RS423 upgrade for the Slogger Plus 2

daveejhitchins wrote:I'd be gobsmacked if someone could make that much of a mess laying out a circuit :shock:


Me too, but I can't think of any other explanation.....
by hoglet
Mon Feb 11, 2013 9:11 pm
Forum: hardware
Topic: RS423 upgrade for the Slogger Plus 2
Replies: 62
Views: 5264

Re: RS423 upgrade for the Slogger Plus 2

The NAND gate at pins 1, 2 and 3 takes as inputs Phi2 and pin 5 (WRN) from the 2681. However, it looks like WRN is an input to the 2681, not an output; so this makes no sense. I've traced enough of the circuit to agree. The 7400 is meant to be generating active low RD and WR from R/W gated with Phi...
by hoglet
Mon Feb 11, 2013 9:11 am
Forum: acorn atom
Topic: Atom Colour Board Thread
Replies: 147
Views: 22885

Re: Atom Colour Board Thread

flynnjs wrote:I think there might be one in PACE


Found it - thanks, I'll take a look:
https://svn.pacedev.net/repos/pace/sw/src/platform/zx/trs/dblscan.vhd

Dave
by hoglet
Mon Feb 11, 2013 8:49 am
Forum: hardware
Topic: RS423 upgrade for the Slogger Plus 2
Replies: 62
Views: 5264

Re: RS423 upgrade for the Slogger Plus 2

By my reckoning pin's 1 and 4 of the chip labelled as a 7400 are outputs, because they drive pins 5 and 6 of the SCN2861 (WRN and RDN) which are inputs. A 74LS02 would fit this pinout, but then the wiring around pins 8, 9, 10 makes no sense. To me, it's looking likely that there is a mistake on the ...
by hoglet
Mon Feb 11, 2013 8:21 am
Forum: hardware
Topic: RS423 upgrade for the Slogger Plus 2
Replies: 62
Views: 5264

Re: RS423 upgrade for the Slogger Plus 2

I wonder if the 7400 and 7404 labels on the board are the wrong way around. The connections make much more sense if that this the case. Or maybe the 7400 is really something else. Dave OK, I'm stumped as well. The more I stare at the wiring around the 7400 the less sense it makes. Any chance you co...
by hoglet
Mon Feb 11, 2013 7:51 am
Forum: hardware
Topic: RS423 upgrade for the Slogger Plus 2
Replies: 62
Views: 5264

Re: RS423 upgrade for the Slogger Plus 2

4) I discovered something which I don't understand at all. Pin 3 of the 7400 is connected to pin 8 of the same IC, with no other junctions or opportunities to connect anything into this line. The weird thing is, pin 3 and pin 8 are both outputs, so connecting them together makes no sense (not to me...
by hoglet
Sun Feb 10, 2013 10:19 pm
Forum: acorn atom
Topic: Atom Colour Board Thread
Replies: 147
Views: 22885

Re: Atom Colour Board Thread

Anyone found any VHDL on the net for a line doubler? :D :D :D

I hate re-inventing the wheel....
by hoglet
Sun Feb 10, 2013 10:09 pm
Forum: acorn atom
Topic: Atom Colour Board Thread
Replies: 147
Views: 22885

Re: Atom Colour Board Thread

Hey all, The saga continues...... Today I started working on a new Colour Board design that will generate a proper line-doubled VGA signal directly. This should allow the use of any LCD monitor with an Atom, without the need for a scan converter (like the GBS-8200, which works, but not very well). I...
by hoglet
Fri Feb 08, 2013 9:45 pm
Forum: general
Topic: Today I received.....
Replies: 4225
Views: 225827

Re: Today I recieved.....

A set of these: IMG_0089.JPG It's a Papilio One FPGA prototying board with a couple of the more interesting Wings. http://www.gadgetfactory.net/arcade/index.php?n=Main.Hardware I've got plans to add a proper VGA output to the Atom using it. But in the mean time: IMG_0091.JPG :D :D :D :D :D
by hoglet
Fri Feb 08, 2013 9:27 pm
Forum: acorn atom
Topic: Atom Colour Board Thread
Replies: 147
Views: 22885

Re: Atom Colour Board Thread

I've just finished building my version of this circuit and it's working, but have a couple of questions for Dave / Hoglet.... How exciting =D> =D> =D> =D> =D> I have not populated the area that replicates the two transistors in the Y line on the Atom board as I wanted to find out if I needed them b...
by hoglet
Thu Feb 07, 2013 6:57 am
Forum: hardware
Topic: Electron Second Processor project
Replies: 228
Views: 19871

Re: Electron Second Processor project

With the new setup, the delay is greater than 70ns but also the mark-space ratio has changed. Rising edges are delayed by 120ns, but falling edges are only delayed by 60ns. The high period is thus about 200ns duration. I reckon this is now a pretty accurate emulation of Phi2, but I don't quite unde...
by hoglet
Wed Feb 06, 2013 10:01 pm
Forum: archive submissions
Topic: Boffin -Addictive 1985 uefHQ
Replies: 12
Views: 1335

Re: Boffin -Addictive 1985 uefHQ

Would you expect this to work in BeebEm?

CHAIN "BOFFIN" loads 11 (hex) blocks then results in a Bad Program

*RUN BOFFIN again loads 11 (hex) blocks then reboots

Dave
by hoglet
Wed Feb 06, 2013 9:22 pm
Forum: acorn atom
Topic: Atom Colour Board Thread
Replies: 147
Views: 22885

Re: Atom Colour Board Thread

OK, switched monitors to my HP LP2065 and got some slightly better results. But I still think this is the wrong approach!! Surely measuring the R, G and B voltages coming out of the colour board is the most accurate way, and eliminates any dependency on the camera and monitor. Anyway, here's a zip w...
by hoglet
Wed Feb 06, 2013 8:58 pm
Forum: acorn atom
Topic: Atom Colour Board Thread
Replies: 147
Views: 22885

Re: Atom Colour Board Thread

Phil, I spent a good couple of hours trying to take a decent set of photos on the Bravia, and I've completely failed. The colours in the photos look nothing like the colours on the screen, and there's terrible moire interference between the camera and the TV. Here's one example: IMG_0011.JPG The ora...
by hoglet
Mon Feb 04, 2013 8:59 am
Forum: hardware
Topic: possible HDMI direct output
Replies: 29
Views: 2768

Re: possible HDMI direct output

This has got me wondering if a weird hybrid is possible, a little board that plugs into the 6847 socket, containing an FPGA emulating a 6847, but instead of outputting Y/PA/PB, it would output SVGA directly on PL4. I guess it would have to effectively contain a scan doubler though. These modules lo...
by hoglet
Mon Feb 04, 2013 7:50 am
Forum: acorn atom
Topic: Atom Colour Board Thread
Replies: 147
Views: 22885

Re: Atom Colour Board Thread

Dave / Hoglet I've just made the board for your video circuit, but find I don't have any 2N5551s, and they seem to be US stock on farnell so £15 before I order anything :( where did you get yours from ? Failing that would a BC548 be a suitable replacement, as I have a load of those I bought for mak...
by hoglet
Mon Feb 04, 2013 7:41 am
Forum: acorn atom
Topic: Atom Colour Board Thread
Replies: 147
Views: 22885

Re: Atom Colour Board Thread

Phil, Lots of male atom PSU connectors which seem quite rare. If you have one of these going spare, it would be really appreciated. The one in my Atom is not the right footprint, and is going to snap off soon. Does anyone know the official size of the imperial original? I think Charlie worked this o...
by hoglet
Sun Feb 03, 2013 10:14 pm
Forum: acorn atom
Topic: Atom Colour Board Thread
Replies: 147
Views: 22885

Re: Atom Colour Board Thread

I'll translate the Dutch text about the principles of the Colourboard and post it here when it's ready. That would be great. I think I have most of it figured out, with the exception of the noise killer. At a guess, this looks like it might be stopping (or extending) the 6502 clock. But I'm not sur...
by hoglet
Sun Feb 03, 2013 10:04 pm
Forum: acorn atom
Topic: Atom Colour Board Thread
Replies: 147
Views: 22885

Re: Atom Colour Board Thread

Were the results of your last post re artefact removal on your real monitor or the Bravia TV? Maybe these results will lead to a better colour board which could even??? include some pins with the 1V resistors you mentioned for some straight through / "off-the-shelf" Phono->SCART connectiv...
by hoglet
Sun Feb 03, 2013 3:40 pm
Forum: acorn atom
Topic: Atom Colour Board Thread
Replies: 147
Views: 22885

Re: Atom Colour Board Thread

A bit more progress this morning with crosstalk inducing slight display artefacts onto the luminance signal. I wanted to get to the 6847 with the scope, to see if I could figure out which signals the crosstalk was coming from. So, I removed Phill's Colour board (which was being used for the 8K RAM a...
by hoglet
Sat Feb 02, 2013 10:08 pm
Forum: hardware
Topic: possible HDMI direct output
Replies: 29
Views: 2768

Re: possible HDMI direct output

Hi Kees, Yes, I have seen Keith Howell's pages. Do you know if the VHDL is available anywhere? Googling for "entity mc6847" shows up a couple of designs. This one looks interesting, as it looks like it might output VGA. https://svn.pacedev.net/repos/pace/sw/src/component/video/mc6847.vhd T...
by hoglet
Sat Feb 02, 2013 8:04 pm
Forum: hardware
Topic: possible HDMI direct output
Replies: 29
Views: 2768

Re: possible HDMI direct output

Hi Mark, Did you ever get any further with your Spartan based design? I've been thinking of having a go at something similar for my Atom, and am looking for something to prototype on. I was drawn to the Spartan 3A because it might be possible to feed the 6847's Y, PA, and PB signals directly into th...
by hoglet
Sat Feb 02, 2013 7:38 pm
Forum: acorn atom
Topic: Atom Colour Board Thread
Replies: 147
Views: 22885

Re: Atom Colour Board Thread

I made up a SCART cable today and tried my little board on my old 32" Sony Bravia and the picture was pretty reasonable. In 256x192 mode with alternating black and white lines I get a consistent width lines. It's much worse on the GBS 8200. The Atom's pixel clock is 7.16MHz. I suspect that the ...
by hoglet
Fri Feb 01, 2013 8:45 pm
Forum: acorn atom
Topic: Atom Colour Board Thread
Replies: 147
Views: 22885

Re: Atom Colour Board Thread

Forgive my ignorance on this (as I don't even know what output(s) the various incarnations of the colour boards produce) but would it not be possible to rig up some kind of COLOUR BOARD O/P -> SCART / VGA / HDMI or even RGB phonos? The latter two would then being usable on the many inputs provided ...
by hoglet
Fri Feb 01, 2013 8:00 pm
Forum: acorn atom
Topic: Atom Colour Board Thread
Replies: 147
Views: 22885

Re: Atom Colour Board Thread

Dave, just as a slight aside - do you think pushing the TTL outputs from the elk/beeb through transistors would eliminate the "snow" effect you sometimes get on the 8200? The Beeb outputs are properly driven (it's the same emitter follower transistor configuration). I think the snow effec...

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