jQuery default JSON parser for AJAX calls

By default, jQuery auto detects the response format of an AJAX request and uses a predefined list of converters to use. Here's how I set the default converter when an AJAX call returns JSON data:

$.ajaxSetup({
    converters: {
        '* text': window.String,
        'text html': true,
        'text json': parseDotNetJson,
        'text xml': jQuery.parseXML
    }
});
function parseDotNetJson(data) {
    return JSON.parse(data, function(key, value) {
        if (typeof value === 'string') {
            var a = /\/Date\((-?\d*)\)\//.exec(value);
            if (a) return new Date(+a[1]);
        }
        return value;
    });
}

I place this code in the root of a script file. I use this to convert dates parsed to JSON by ASP.Net MVC.

More info

jQuery auto detects types

jQuery.ajax default converters

jQuery.setup

Convert .Net MVC Json dates

DevExtreme - Get dxTextBox value the JQuery way

Fairly simple. Let's say you have this:

<div id="batch-id"></div>

Which is converted to a dxTextBox:

$('#batch-id').dxTextBox();

And you want to get the value the official way:

var x = $('#batch-id').dxTextBox('instance').option('value');

You can set the value this way:

$('#batch-id').dxTextBox('instance').option('value', 666);

You can also directly query the element using classic jQuery:

$('#batch-id input').val();

CoCo 2 with a PC 3.5 floppy drive

Now for something a little bit more vintage. I've revived my TRS-80 Color Computer 2 and wanted to give it an ultimate go with all the stuff that's now available on the net. The CoCo community is not very large, but it's still there. So I went on and tried to get the poor old thing to communicate with the now popular DriveWire 4 through a serial cable. But that's another blog post.

I'll talk here about the 3.5 inch floppy drive. They're still kind of available and cheap so, they're good replacements for the original 5.25 drives, and more reliable too. I looked around for many hours and found much complicated stuff, but I just wanted to sink a couple of boats in Battle Stations. So I decided to write this post, should it be helpful to someone one day, who also decides to blow some dust off their CoCo 2 ;)

Hooking the drive to a CoCo

Alright so here's what you'll need, no modification, no hack, no fiddling with the circuits:

• A CoCo 2 system with a floppy disk controller.
• A floppy cable, straight trough, with the two kinds of connectors (one "edge connector" for the controller, and a "plug connector" for the drive) Those used to be common. You could also use a edge to plug converter and use a more nowadays-common "all-plugs" cable.
• A 3.5 floppy drive
• A power source to power the drive.

This part is fairly easy. You just hook the drive to the controller. And that's it. I used the two connectors that were the closest to each other. Forgive the arrangement, it's messy, but it works:

I first used a nearby PC (they're everywhere in my appartment!) to power the drive.

Start the CoCo, type in DRIVE 1, and you're all set. You can insert a floppy, DSKINI1 on it, LOAD" from and SAVE" to it. You might have to put a piece of tape on the HD hole of the floppy to make it low density.

What if I need to use Drive 0?

For technical reasons, all standard PC floppy drives are hard wired to be DRIVE 1. Some have jumpers that make this configurable:

See DS1 and DS0? DS1 is jumped. You would have to unjump DS1 and jump DS0.

But that's not all. The CoCo uses a different technique than on PC to select which drive it talks to so the ordinary twisted cable won't work:

"There are 34 wires in the ribbon cable (1-34). Each odd wire is Ground. Each even wire is a control or data line. The Drive Select 0 and Drive Select 1 wires (numbers 12 and 14) are separated by 1 ground wire (13). 

You have to carefully remove the ribbon cable from the connector, seperate those three wires (DS0, GND, DS1) from the others and twist them so that the two drive select wires switch positions, then put all 34 wires back into the connector." -- Source

Writing a CoCo DSK image to a floppy from a PC

Here's what you'll need:

• A PC (The OS will define which software you'll use. I used Debian.)
• Another floppy drive attached to the motherboard of the PC. USB drives can't work.

I'll only talk about how to do it using Debian. Other Linux distros should have no real problem adapting the instructons. As for Windows, you're on your own, sorry... You might just want to get yourself a nice LiveBoot distribution of Ubuntu. Go ahead, the Linux turn nowadays is a fun and friendly journey! ;)

Ensure you have your floppy drive hooked to your motherboard. Then, you'll need fdutils so in a terminal:

sudo apt-get install fdutils

As a side note, no additional configuration of the utils is needed. apt will also install mtools as a dependency which will come with the proper /etc/mediaprm file configured with the correct CoCo entries in it.

Next:

• Put a piece of tape on the HD hole of the floppy to make it low density ;)
• Run the following command to tell the system how to format the disk. You'll have to run this every time you put a floppy in the drive:

sudo setfdprm /dev/fd0 coco1

• Format the disk:

sudo fdformat /dev/fd0

• Write the image to the disk:

sudo dd if=bstations.dsk of=/dev/fd0 

• If any of the above two commands fail to read data from the disk, you might try to reenter the fdformat command and try again. this happened to me a couple of times.
• Put the disk in the CoCo drive and sink some boats ;)

Reading a CoCo floppy to a DSK image on a PC

Install fdutils as explained above. Next, issue the setfdprm command explained above and enter:

sudo dd if=/dev/fd0 of=myimage.dsk count=315

If the dd command fails to write to the disk, you might have to enter the setfdprm command a couple of times before the dd command works, at least each time a floppy is inserted.

Floppy power source

If you want to build a power source yourself, you only need to provide 5V. Most floppies will need around 1A. No need for 12V. Be aware that the cartridge port of the CoCo has a 5V pin, but it is rated for 300mA only, so be safe and use an external source.

I used a spare D-Link wall adapter and replaced its connector with a floppy power connector I had left.

Hook both a 3.5 floppy drive and a CoCo drive to the CoCo

This is fairly easy. You'll need to ensure your floppy cable has enough connectors, and that there is no twist in between the used connectors.

Next, proceede to a "dental extraction" on the connector that'll connect the CoCo drive. Look at your original CoCo drive cable, if you have one, and look at the DRIVE 0 connector. You'll notice some pins (3) are missing. You'll have to remove them from your connector as well. So gently (those things are fragile like crystal) open the connector, remove the cable, remove the uneeded pins, put the cable back and reassemble the connector. Here's mine:

Notice the three removed pins. This is for DRIVE 0.

This is the whole setup.

There you have it. You can now backup your old 5.25 floppies to more trustworthy 3.5's!

You'll need one 3.5 for each 5.25 side, but who cares ;)

What if my 3.5 drive is DRIVE 0?

Then you want the CoCo as DRIVE 1. The process is the same, but the removed pins will be different:

This is for DRIVE 1 on the original CoCo cable. As a side note, also notice the straighten twist on the modified cable.

Additional infos

Here's a great repository of disk images I use myself. You'll find Battle Stations somewhere in there ;)

So this is what has worked for me. I tried a lot of things and failed many times, wondering each time what was wrong. Don't give up! I'd like to thank the guys at #coco_talk on freenode, they've been a great help and very friendly!

Feel free to ask any question in the comments below!