vsync cable.

This is the right place to discuss on how to implement hardware vsync, adding a VIA or AY chipset, puting multiple roms, or how to design a new flash expansion card.
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highwayman
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vsync cable.

Post by highwayman » Fri Oct 12, 2007 8:20 pm

just a quick question for people who have one,
does it mess with the tape loading so it has to be removed first?

if it does then why not just linik the sync output and the tape-relay signal through a nand gate or something so the sync signal is blocked when the tape runs?

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Re: vsync cable.

Post by Dbug » Fri Oct 12, 2007 9:20 pm

highwayman wrote:just a quick question for people who have one,
does it mess with the tape loading so it has to be removed first?

if it does then why not just linik the sync output and the tape-relay signal through a nand gate or something so the sync signal is blocked when the tape runs?
Yes it messes the tape loading, and yes it would be nice to use the tape relay to automatically enable sync when it's off.

I asked the same question some years ago on the newsgroup, and failed to get any answer.

If you can get that to work easily, I would happily try that in my atmos, instead of having to plug/unplug the cable each time I want to do a test.

Ideally, a simple kit with minimal soldering could be done, so a number of people could install that in their machines.

There are not many applications using that, because basically we are something like three people having done the test (Fabrice, Twilighte and me), but if you want to try, don't hesitate checking with my tech demo:
http://www.pouet.net/prod.php?which=24190

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Post by mmu_man » Fri Oct 12, 2007 10:16 pm

It should be possible with a transistor (maybe a fet) and 2 resistors... would have to look it up...
The problem being the relay is NO (normaly open), and we don't have any Vcc handy on the plug... we could at worsetake it from printer port.

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Post by Dbug » Sat Oct 13, 2007 11:39 am

I guess there are two possible types of implementations:
- outside
- inside

The outside would need two male DIN connectors to plug on the Oric tape and rgb sockets, two female DIN connectors on which plugging the real tape drive cable and tv cable. And then yes, you have to figure out where to get the power from. Advantage is that you can plug that on any oric without any modification, but it's a bit of overkill cost wise with the number of sockets.

Now this could also be a more complicated device, which could include things like a better self powered RGB cable, or a composite output to connect the oric on video projectors, record on video recorder, or connect to non rgb screens with a better quality than the original antenna output.

The inside method would be what I would do on my development Oric machine: A set of components to solder directly inside the case, and at this point we have a lot of places where to get power from :)

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Post by highwayman » Sat Oct 13, 2007 12:02 pm

mmu_man wrote:It should be possible with a transistor (maybe a fet) and 2 resistors... would have to look it up...
The problem being the relay is NO (normaly open), and we don't have any Vcc handy on the plug... we could at worsetake it from printer port.
i was thinking of an internal mod using the vsync signal and the relay drive taken directly from the via.

you can put a ttl chip in the empty space that was used for double-eprom controll with the power-pins going through the board and the rest bent out from the chip.

when i find my oric i'll try it.
1chip, 3 wires, no stupid plugs & such.

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Post by Twilighte » Wed Nov 10, 2010 3:03 pm

I've always hated the idea of internal hardware hacks in order to get things done because it requires someone both willing to corrupt their pristine Oric and mess around with hardware.

There is a better solution and one that has an added bonus.

We take the power plug that would usually plug into the oric and put it into a socket in a small abs box.
This then connects through a reset switch to a flying lead with the power plug for the oric. Now we have a small power supply in the ABS box.

We then connect a small bridge rectifier (and maybe a capacitor to reduce spikes on the dc output) to the power supply. This gives us a 9volt dc supply.

A resistor and LED may then be added to provide visual indication of the power and reset confirmation.

The dc supply is then fed through the Tape port pin for remote switch (internally the remote connectors go to a normally open switch in the Oric) and the other side of the switch goes to a small subminiature relay coil (SPCO or SPDT). The negative going to ground (pin 2 on Tape port i think).

The Tape Input on the Tape Port then goes to the armature of the Relay switch. The Normally closed contact connects to the Sync pin 4 of the RGB port (socket on back of Oric) and the normally open contact connects to a new 3.5mm socket on the side of the ABS Box for Tape input.
The other connector of this socket connects to ground.

A further socket may be provided for Tape output since now the socket on the back of the Oric is now being used.
Another socket may also be provided for Audio output.

Further switches may be provided to mute all sound (links Audio out to ground), Monitor tape save (links tape input socket to Audio out) and Monitor Tape load (links Tape output to Audio Out).

Unfortunately there is no way of muting the internal speaker whilst still permitting audio output to external amplifier (without internal changes to Oric).

I will provide a curcuit diagram when i get time but essentially no internal Oric changes are neccesary :p

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Post by Dbug » Wed Nov 10, 2010 6:49 pm

Internal or external is not the problem as long as it is automatic.

All the signals you are talking about are available on both side of the connectors, it's just a matter of prettiness.

I can understand the will of keeping the machine pristine and unmodified, but you may also want to consider wanting to keep the machine LOOKING unmodified (which obviously a big box and cable on the outside is not going to help with) :)

Now of course, with the idea of the box one could think farther, and use the built-in power to actually give the power to the slow-commutation switch of the scart connector.

I also reminds that somebody posted a message earlier about the box he made:
http://www.defence-force.org/computing/ ... /index.htm

So possibly a full-schematic of the "box to have" device would provided:
- standardized power led + reset button (hopefully compatible with microdisc)
- the automated "tape relay based" vsync system
- the selfpowered scart cable
- the "mini jack" for audio output
- the "audio output to tape in" speech synthesizer hack

Did I forget anything?

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Post by Twilighte » Wed Nov 10, 2010 11:47 pm

I think the speech synth hack was Tape out to audio out

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Post by Dbug » Sat Nov 13, 2010 3:29 pm

While Twilighte is investigating the "external" solution, I was investigating the "internal" way of doing the automatic vsync switching.

On the oric schematics (http://oric.free.fr/IMAGES/oric1-1s.gif) one can see there is an internal relay in the Oric already, which is charged of enabling/disabling the contact between the pins 6 and 7 of the tape DIN connector.

Physically on the motherboard it's a 8 pin component, and by checking on various motherboards photos I found out that there are two models:
- UDM-105N
- OKI D51A05

It appears that these components are standard SPST (Single Pole Single Throw - http://en.wikipedia.org/wiki/Relay#Pole_and_throw relays).

Indeed when looking in detail on the motherboard, only 4 of the 8 pins are connected, the two for the power input, and the two others connected to the DIN connector.

Twilighte found a data-sheet for an equivalent product, HE700 (http://www.hamlin.com/specsheets/HE700.pdf), which shows that there are other variants where the 8 pins are actually usable for either:
- select two individual sources at the same time
- select between two outputs from the same source

So a possible solution would be to unsolder the existing SPST model, and replace it by a SPDT model, which would give the possibility to select between two destinations, one could be the existing tape remote control, the other one being the video sync signal.

In short: 8 pins to unsolder, remove the old device, replace by a new one with the same form factor, add a small wire between the sync and the other pin on the relay.

Does that looks like something doable? Is it still possible to find this kind of component?

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Post by Twilighte » Sun Nov 14, 2010 2:34 pm

Dbug wrote:So a possible solution would be to unsolder the existing SPST model, and replace it by a SPDT model, which would give the possibility to select between two destinations, one could be the existing tape remote control, the other one being the video sync signal.
You almost have it but not quite so simple.
First you need to locate the Tape socket and cut through the track connected to Pin 3(Tape in). Now you need to make up two wires, one connecting the pin 3 and the other connecting to the other side of the broken track (or where its connected to C6 (Capacitor)).
Now make a third wire from Pin 4 of the RGB socket.

Now replace the Relay with an 8 pin SPDT or SPCO relay such as those mentioned above or LU-5 which is easily available.
Now cut the tracks leading to the relays existing switch and connect the C6 wire to the common contact, 'Tape In' wire to the Normally open contact and RGB Sync wire to the Normally closed contact.

To illustrate this the first diagram below is of the existing relay.

Image
The diagram below is of the changeover Dbug is suggesting..

Image

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