- Difficulty:

- Terrain:

Size: (regular)

This cache involves a walk of approximately 1.7 km.s from the nearest parking spot on Wellington Road and there is a hill involved.

At the published location, you will find a device requiring 4 AA batteries. You are required to "button in" 6 numbers given to you as either Hex or Decimal.

**Background**

Computers run using a number system called binary (base 2) consisting of just 1’s and 0’s.

Our normal number system is decimal (base 10) with digits from 0 to 9. In decimal, the number 4056 is made up of (reading right to left) 6 x 1 (6) + 5 x 10^{1}(50) + 0 x 10^{2} (0) + 4 x 10^{3} (4000).

In binary, the number 1101011 is made up of (reading right to left) 1 + 1 x 2^{1} (2) + 0 x 2^{2} (0) + 1 x 2^{3} (8) + 0 x 2^{4} (0) + 1 x 2^{5} (32) + 1 x 2^{6} (64) = 107 decimal.

Each binary digit is called a bit (shortened form of binary digit). A group of 8 bits is called a byte and can represent numbers between 0 and 255. A byte can also be split into two halves called a nybble (or more commonly spelt as nibble).

Writing numbers in binary is tedious, so normally they are written in Hexadecimal (base 16) using digits from 0 to 9, then A – F for each nibble, with A being 10 decimal, and F being 15 decimal. Any binary number can be easily converted to Hexadecimal (Hex for short) by taking 4 binary digits (a nibble) at a time starting at the right hand side (least significant digits) and converting them, then moving left.

So 0110100110111001111 is 34DCF. Using a calculator, this shows a value of 216,527.

The bit patterns for hex are:

Decimal Hex Binary

0 0 00001 1 0001

2 2 0010

3 3 0011

4 4 0100

5 5 0101

6 6 0110

7 7 0111

8 8 1000

9 9 1001

10 A 1010

11 B 1011

12 C 1100

13 D 1101

14 E 1110

15 F 1111

**Bootstrapping**

In the early days of computing, before Read Only Memory devices were available, to start a computer, a small program had to be “buttoned” in on the front console of the computer. This was done in binary using a set of switches. That was called Bootstrapping the computer, and that’s where the term for Booting or rebooting a computer came from.

Once the small program was entered, it could then load a slightly smarter program from cards or tape or disk. That could then load the monitor or operating system so that the computer could be used.

Your task today will be to get a quick idea of what it must have been like in the early days.

**The Cache**

Like all the BYO Battery caches, you need to install your 4 AA batteries in the provided holder. Switch the device on. When you are ready, press the red Start (Check) button to start. You will be given a series of 6 random numbers between 0 and 255, some in decimal, and some in Hex. Decimal numbers will be preceded with a ‘D’ while Hex numbers will be preceded with an ‘H’. Your job is to set the switches at the bottom to represent the requested number. When you think you have got it, press the check button.

**Example:** In the above photo, you are requested to button in Hex 1F. As you can see by the switches, the last 5 switches need to be on, with the first 3 off.

If you are correct, it will move on to the next number. Otherwise, it will tell you the current number you have buttoned in. You can then fix it and try again until you get it right.

Once all 6 numbers have been buttoned in, you will be given the final co-ordinates of the actual cache. Good luck.

This device was initially tested by an eight year old girl, and subsequently by a number of adults at a couple of Cache Carnival events.

**
Additional Hints**
(Decrypt)

Qrivpr: Ybj Sbex

Pnpur: Gerr Ebbgf

Pnpur: Gerr Ebbgf

Decryption Key

A|B|C|D|E|F|G|H|I|J|K|L|M

-------------------------

N|O|P|Q|R|S|T|U|V|W|X|Y|Z

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