View Full Version : Why not Hydra kit?

Jack Crenshaw
01-18-2009, 08:14 AM
I've not heard much mention here about the Hydra game devel kit. With the keyboard, mouse, and VGA interface, it would seem to be the ideal way to get what amounts to a general-purpose Propeller-powered computer. And with the optional 512K RAM addon, it would have enough to keep heater busy for the rest of his natural days.

There must be a downside. What am I missing?


Mike Green
01-18-2009, 08:26 AM
The biggest problem (for me) with the Hydra (and I have one) is that you can't use a VGA display at the same time you're using an expansion card since the I/O pins are the same. If you're happy working with a TV display, you'll be fine. I do like the Hydra's use of a standard 128K EEPROM and an additional 128K EEPROM on each expansion card. The 512K RAM card uses a couple of the other I/O pins for control lines (like the HydraNet and one of the programming interface pins) which makes its use a little "funky". I tend to use the Protoboard with the Accessory kit. It's easy to add an SD card with SparkFun's adapter and a couple of wires. Another good alternative is the Demo Board. I've added an SD card using the little breadboard. There's also a 32K SPI SRAM you can get and wire in using 4 of the 8 uncommitted I/O pins (with the SD card using the other 4).

01-18-2009, 08:27 AM
kits like that can be nice but have the down side of having pins already tied up. I use the SpinStudio (http://ucontroller.com/) kit because I can easily connect many different periferals but none are hard wired so I can emove or change as needed.

01-18-2009, 10:19 AM
One catch would be the price - adding a $59 add-on board to a $12.50 propeller, especially when you can get a 512k memory chip from futurlec and others for $8.50 - and maybe a few glue chips at 25c each.

Looking at the hydra it looks like it uses an 8 way data bus, and clocks in the address lines serially. That could be done with HC595 chips and would use a similar number of pins. There are all sorts of options ranging from direct addressing using 26 pins, right down to doing the whole thing serially and maybe only using 3-5 pins. Somewhere in the middle is a compromise for speed vs pins. I'd tend to veer towards having an 8 way data bus and using it for data, but with a few control lines, also using it as the lines to latch some 273s or 373s. Something like 12 lines and certainly a lot faster than pure serial.

You may not need 512k either. 128k chips are cheaper and use an sd card for mass storage. Use each type of memory for different purposes eg flash memory has huge storage but wears out. sram is more expensive but never wears out. So use sdram for mass storage of files and data, and use sram for the program part where data is being shuffled round lots within a program.

But it looks like heater is stuck with the mundane task of trying to get the simulator to do just one instruction.

Jack Crenshaw
01-18-2009, 01:15 PM
Ok, guys, thanks for the suggestions. I have a _LOT_ to learn!


01-18-2009, 02:31 PM
...and odds are you are gonna have a good time.

BTW: I really like this board:

Runs @ 96Mhz, which is kind of the upper safe limit for the Propeller

TV Graphics work nicely with a PC capture card of some kind. I work on a laptop most of the time, so it's easy to just connect both via USB and go.

Pins are available as dedicated ports (HYDRA expansion + VGA) & keyboard, mouse, serial, 2 DB9 atari style joystick ports, SD card, composite video out, mono audio out, and of course, your handy debug LED. Program via USB with Prop Plug. I recommend one of these, as it's an easy interface to the chip, and can be moved around. Just leave one on the end of a USB cable, and do your thing.


I/O pins are also available on an IDE connector port. Easy Cheezy connection to your breadboard of choice.

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01-18-2009, 02:40 PM
I'd love a Hydra but a few things for me:

1. I have a hard time justifying the expense of all my toys to "her indoors"
2. The RAM would be great but I don't want to me emulating 1976 prices for PropAltair
3. Driving the RAM requires enough code that it will not fit in my current single COG 8080 emulator and the speed is not good.
4. A big point was to be sure that as many people as possible were able to try out PropAltair if they wanted so I determined that a Prop Demo board with no extras would be the best base. Currently that limits CP/M to 24K HUB RAM but at least it show that it works. I always want to keep a version at that level.
5. I got a kick out of soldering up my own "demo board" with a DIP Prop. Amazing how few components you need to get it to run. I had all the required components in my junk box anyway.

So, nice to have but not quite it for me.

For RAM I'm looking forward to the Prop/CPLD/RAM board from Leon. If that's not here soon it's soldering iron and string time again:)

For me, the past is not over yet.

01-19-2009, 01:58 AM
I think the real value in the Hydra kit is the book and all the examples.

These really helped me getting started with the prop...

Living on the planet Earth might be expensive but it includes a free trip around the sun every year...

Experience level:
[ ] Let's connect the motor to pin 1, it's a 6V motor so it should be fine.
[ ] OK, I got my resistors hooked up with the LEDs.
[X] I got the Motor hooked up with the H-bridge and the 555 is supplying the PWM.
[ ] Now, if I can only program the BOE-BOT to interface with he Flux Capacitor.
[ ] I dream in SX28 assembler...


01-19-2009, 03:12 AM
Yeah, I forgot about the book. Sounds great, perhaps I can get the go ahead from "her indoors" to purchase a book, if you see what I mean.

For me, the past is not over yet.