Build your own robot - at the thought, a thousand daydreamy childhood hours flooded back. Make it pick up your room. Make it feed the dog. Make it hit your brother on the side of the head.

So when the venerable Lego company announced the release in October of Mindstorms, a Legobased "robotics invention system" produced in close co-operation with that geek mecca, the Massachusetts Institute of Technology's Media Laboratory, there was only one option for a thirtysomething technology writer: I had to have it.

The arrival of the enormous, patterned blue box is the closest I've come to recapturing the rapture of a childhood Christmas morning. No adult gift can ever possibly evoke that thrill of dumping hundreds of parts - 782, to be exact - all over the floor. It's an intrinsically child-like moment.

In the box, there are hundreds of the chunky bricks familiar to millions of children (and, of course, after being painfully stepped on, parents). Then there are dozens of wheels, gears, pegs, axles, strange little grey parts, tubes like tiny hoses, a pair of caterpillar treads, and special bricks with wires attached, which are the touch and infra-red light sensors, and two tiny brick-encased motors. There's a CD-Rom for your Mac or PC which takes you through the steps of learning to programme your very own robot. There's an infra-red unit which you attach to your computer, from which your robot downloads your programmes into its microchips. Cool.

Then there are the two most important pieces: the small yellow "programmable RCX brick" with the robot's brain, and the large human island sitting in the middle of the sea of Lego with what the geek world refers to as the meat brain. Could meat brain cope with robot brain?

Well, let's put it this way. Nothing withers the technology writer's courage so utterly as the phrase, "ages 12 and up" on a product. Inevitably, that means a 12-yearold will have it composing symphonies by late afternoon and pondering solutions to the problem of third world debt, whereas I will still be trying to make it go forwards instead of backwards.

Nonetheless, in defence I must point out that Mindstorms kits are, I would guess, far more likely to end up in the hands of techminded adults than 12-year-old children. Partly this is because the system is not cheap - around £160 in the UK, with expansion sets costing around £40. And partly this is because any adult who claims to be buying it for a child is probably lying and has every intention of figuring out how to make the programmable brick reverse, spin around, and beep three times.

"It's the toy you wish you'd had when you were a kid, isn't it?" insists a Lego spokesman, failing to suppress a gloating tone. "In the past, to do something like this, you'd have needed a background in programming and computer design, and a soldering iron."

BUT Mindstorms hardly qualifies as a toy. Lego began working with MIT on the concept of programmable products back in 1984. The programmable brick is a microcomputer capable of handling 1500 simultaneous commands and holding five separate programmes in its memory.

The light and touch sensors interact with the robot's environment, feed data back to the brick, and cause it to respond in whatever way you decide it should. Using the gears and tiny belts, it's possible to make arms or cranes or walking legs. You can give the robot sensory feelers which can make it reverse when it hits a wall, or avoid going off the end of a table. And boffins will quiver with excitement at the news that you can programme it in the computer language Visual Basic as well.

So, it was time to start. Loading the CD-Rom, I followed the directions of the slow-speaking American voice. Several tutorials - or "missions" - need to be accomplished before the CD-Rom lets you access the programming section, a good thing for children because it keeps them on a step by step track and utterly necessary for adults, for the same reason.

The missions cleverly blend spoken directions, pictures, interactive buttons, and video clips to show you exactly how to accomplish each task. "Look at the display. Is a number one showing?" asks the Voice. I click the "yes" button. "Cool," says the Voice. He adds other bits of encouragement throughout the programme. "So far, you're brilliant." "You are amazing."

Why, thank you. I never thought anyone would notice. Are you free for a drink after this mission?

Initially, you have to do very basic assembly on a robot core called Pathfinder One. This is where you remember all the trials and tribulations of Lego and those bouts of childhood frustration. You need to find two button-sized black "skid plates" amidst the rolling waves of Lego on the carpet. You eventually find one. After digging through the pile, you begin to think you've been left one skid plate short. Then, there it is.

Once the basic unit is together, complete with two wheels, you try out the two tiny engines, which have brick connectors which snap on to special lettered spaces on the RCX brick, then the sensors, which have numbered spaces. You run them through a range of tests which teach you how they work.

Then you're ready for programming. Fear not, this involves nothing more arduous than dragging and dropping green blocks onscreen, each of which represents an action, like moving, waiting, or beeping. There are also red blocks which represent commands for whole stacks of green blocks, such as repeating the sequence of actions five times. Lego calls this system RCX code, and it's as easy as linking puzzle pieces.

Or so I thought.

Learning the basics is deceptively easy. I chose an easy set of commands, and dragged and dropped away for an hour or so, setting up a programme for a robot with two touch sensors.

I added some detail to the robot, deciding to drop the plain round wheels and instead build a more elaborate, geared caterpillar-tread mechanism. Another hour passed. I saved and downloaded the program and my robot beeped, acknowledging that its belly was full of my RCX code. I set it carefully on the floor and turned it on. It made a tiny, brief grinding noise and did nothing.

I went out and searched unsuccessfully for a 12-year-old. I was going to have to do it myself.

At this point, you realise what a fantastic teaching tool the robot is. You have to think logically, through every single step. You have to make the structure of the robot work with the intentions of your programme, or vice versa.

Several hours later, it was done. I opted for an insect-like robot, because the units are actually quite small. I gave it long yellow feelers on a swivelling joint which caused one or the other to push against a sensor. I added some details - little hoses, odd bits and pieces. I put it on the floor, set it to its new program, and turned it on. It completed the whole routine - moving forward, backwards, turning. If it hit an object with a feeler it would back up and either beep and turn left or turn right, depending on which sensor had been activated.

I brought it into The Irish Times. "But it's so small," said everyone. I let it run across the floor, as proud as a parent whose child has just taken a first step. "Is that all it does?" asked one reporter. "Can't you make it go downstairs to the canteen and bring some snacks back?"

Lego Mindstorms can be ordered by phone from 0044-845606-2043 and are stocked at the following shops in Dublin:

Electronics Boutique, Dawson Street

PC World, Blanchardstown Smyth's Toy Superstores