You must collect a number of gold nuggets on each screen but once you start doing this the unsupported rocks will start to cave in. Fortunately, past explorers have left blocks of dynamite which you may collect to blast through sealed-off sections.

But watch out! If you blow up any gold in the process, you won't have enough to complete the level. There are four challenging caves to puzzle out. If you become stuck, ESCAPE quits the game.

Game Controls
A - Left S - Right P - Up L - Down CTRL - Blast ESCAPE - Quit Game

Technical Info
The main program, "G.GOLD1", assembles the machine code and loads in the characters and map data. "G.CHARS" is loaded into page &C, and contains both the sprites and user-defined graphics characters, so characters 250-255 are peeked out and defined for the benefit of BBC Master owners.

Machine Code Subroutines

addgo        Adds BCD number in A to number of gold pieces collected.
             Note that to subtract, use &99 for -1, &98 for -1 etc. in
             BCD maths

addsc        Adds BCD number in A to score value and prints it under
             "SCORE" on the screen
                                       
addtnt       Adds BCD number in A to number of dynamite sticks held

border       Prints fancy border around playing area.

cavein       If the character below the rock (see 'rock') is unsupport-
             ed, a zero is written at ('dx','dy2') and one (=rock char-
             acter) is written at ('dx','dy2'+1)

expld        Animated explosions around miner. Decreases TNT by 1.
             'fltop' and 'flbot' are tables of the user-defined chars 
             for the top and bottom of each puff of smoke. 'frame' is an
             index into this data. 'eptx' and 'epty' contain the text
             co-ordinates of the four positions around the miner. 
             'eppos' is an index into this data. For each 'frame' the 
             current puff shape is plotted four times, once at each of
             the four positions. The fifth frame is a blank space 
             (CHR$32) only plotted if the explosion occured within the
             map

initc        Initialises current cave by storing number of gold pieces 
             to be collected in 'golv', resetting TNT counter, and 
             setting miner's co-ordinates to top left of screen

keys         Checks keyboard and moves miner in relevant direction. If
             'scan' returns with the N flag set, the key in question was
             pressed

mksound      Makes a sound. Sound number in A, which is then multiplied
             by 8 to index into 'sounds'. X and Y set to point to this
             sound before a call to OSWORD 7

move         Adds direction number in X and Y (e.g. X=-1, Y=0 for moving
             left) to 'xpos' and 'ypos' and stores in 'ox' and 'oy'. The
             miner is allowed to move if next character is gold or TNT
                                                       
prints       Prints sprite, given the sprite number in A. Calculates
             screen address given the text co-ordinates in X and Y, 
             using the 8-times table, and character row address table

prnum        Prints number (BCD) in A. Note fancy effect of printing the
             letter O in place of zero!

readm        Reads map at co-ordinates in X and Y registers. If X or Y
             are -1 or 32, this is off the map, so 'readm' exits with
             A=5. One byte of screen data holds information about four
             characters, i.e. 2 bits per character. Caves are 32x32
             chars, or 8x32 bytes, big. The correct byte to retrieve 
             from the map is that at offset Y%*8 + X% DIV4. The correct
             two bits to retrieve are those at (X% DIV4) AND 3 EOR 3

rock         The map is constantly scanned, from bottom right to top
             left,  for rock blocks. If one is found, 'fall' is set so
             that next time the rock will start to fall if unsupported

scan         Scans keyboard. On entry, A contains internal key number,
             which is then EORed with &80 before calling OSBYTE &79.
             X=&FF (negative) if the key was pressed

update       Redraws map from current miner's position. Note that the
             true co-ordinates of the miner are ('xpos'+3,'ypos'+3) but
             the top left co-ordinates of the window position on the map
             are ('xpos','ypos')

writem       Writes item in A to map. See 'readm' for more details

bords        Start address of decorative border sprites

cave         Current cave number

fall         Cave-in flag. If scanning routine (see 'rock') finds a rock
             then 'fall' is set so that next time round the rock can
             "cave in" if not supported underneath

quit         Contains 0 if game in progress, -1 if all gold in current
             cave collected, 1 if ESCAPE pressed

xpos,ypos    Miner's co-ordinates
                                                   
xtab         8-times table, a list of the address offsets of columns
             along the screen
                
ytab         List of addresses of the start of each character row down
             the Mode 5 screen