Dr. Andrew Broad
Sinclair ZX Spectrum
Manic Miner/Jet Set Willy
Nomen Clature: a MM/JSW Glossary (under construction)

# The prefix used on this website to indicate a hexadecimal literal.

16-bit word A group of 16 bits encoding one of 65536 possible values. The Spectrum represents a 16-bit word W by a low byte L followed by a high byte H (in consecutive addresses), where W = L + 256*H.

address The location of a particular byte in the Spectrum's memory, from 0 to 65535 (#FFFF). If it is necessary to refer to bytes in 128K memory-banks, their addresses may be given in bank:offset notation, e.g. 3:#C000 refers to the byte at #C000 when Bank 3 is in the #C000-FFFF slot.

address-space A range of addresses used for a specific purpose.

Air A cell-type that the player can move through, but not stand on. Synonyms: Background, Gas. Not to be confused with air-supply.

air-supply The amount of air that you have in a MM room (or a JSW64 room with an air-supply), which runs down and eventually kills you. Not to be confused with Air.

alpha-version A version that is available only to its author.





Background Synonym of Air.

Bad Pause-Bug Fix

beta-version A version made available to a limited audience for testing-purposes, that the author plans to supersede with a gamma-version.

BGB Block-Graphics Bug.

bidirectional HG A horizontal guardian which uses the sprite-frames from one half of its sprite-page when going left, and the sprite-frames from the other half when going right.

binary A number-system in which each digit is one of two possible symbols: 0 or 1.

bit A binary digit, with a value of either 0 or 1.

bitmap Synonym of pixel-pattern.

block Almost a synonym of cell - the difference being that a block is identified by its cell-class rather than its coordinates. Thus it is proper to say "move this Earth-block one cell to the left" rather than "move this Earth-cell one cell to the left".

block-class Synonym of cell-class.

Block-Graphics Bug Synonym of Cell-Graphics Bug.

block-type Synonym of cell-type.

bonus-room A JSW64 room in which collecting each item gives the player an extra life.

bottom third Everything that appears on the screen between rows 16 and 23 inclusive, including the room-title, score and high score (in MM) or number of items collected and time (in JSW), and the remaining lives.

bug An error that makes a game not possible to complete, or even causes the Spectrum to crash, or is the Cell-Graphics Bug.


byte A group of eight bits encoding one of 256 possible values.

cell A particular 8x8 character-square within a room's cellular layout, identified by its coordinates (cell-row, cell-column), and being of a particular cell-class which determines its appearance and behaviour. In other words, a cell is a hole which contains exactly one block. (NB. MM and JSW64 Variant Z can have Custom-cells which belong to no cell-classes.)

cell-class A class of cells which each room defines to have a certain colour-attribute, pixel-pattern and cell-type. In MM, JSW48 and JSW128 each cell-class has a fixed cell-type; in JSW64 the cell-type of each cell-class can be set by the author (globally in Variants W,Y,Z and [; by room in Variants V and X).


Cell-Graphics Bug

cell-grid Synonym of cellular layout.


cell-type The behaviour associated with each cell-class, i.e. whether it's Air, Water, Earth, Fire, Crumbly, Ramp, Conveyor, Trampoline or Trap.

cellular layout A room's 16x32 rectangle of cells - and nothing but the cells. Synonyms: cell-grid, screen-layout.

CGB Cell-Graphics Bug.

character-square A particular 8x8 pixel square on the screen, identified by its coordinates (row, column), and having a particular colour-attribute.

collide "A collides with B" means that B was drawn first, then A was drawn and their pixels (or colour-attributes as the case may be) collided, causing A - not B - to react to the collision. See Collision-Detection and the JSW Guardian-Instance List.


colour-based collision-detection A kind of collision based on the colour-attribute of a character-square that an object touches.



completable (item-/Maria-/bed-/toilet-)



conventional guardian A guardian that is either a horizontal guardian or a vertical guardian.


conveyor A row of Conveyor-cells.




datum (pl. data) A piece of information, typically in a computer-file or loaded into a computer's memory.

decimal Synonym of denary.

denary A number-system in which each digit is one of ten possible symbols: 0, 1, 2, 3, 4, 5, 6, 7, 8 or 9. Synonym: decimal.

diagonal guardian

direction Whether something moves/faces/animates to the left or to the right (in some cases, up or down).


doubly-located items

droplet A Skylab that doesn't go sideways.

dynamic POKE a poke that has to be applied while you are playing the game.

Earth A cell-type that the player can stand on, but cannot move through except by exploiting certain quirky features. Synonyms: Wall, Solid.

elementary cell A cell that is encoded in the room's technical cell-grid. In MM and JSW64 all cells are elementary, but in JSW48 and JSW128 the only elementary cell-types are Air, Water, Earth and Fire, because Ramp and Conveyor are encoded separately from the technical cell-grid.

escalator A conveyor-ramp (achieved in JSW48 and JSW128 by giving Ramp and Conveyor the same colour-attribute, and in JSW64 by setting a special flag).



Fire A cell-type that kills the player on contact, and cannot be stood on even with one of the player's cell-columns above a stand-onable cell. Synonyms: Static Nasty, Plasma.

Floor Synonym of Water.

Forbidden Holy Ground

game A piece of software consisting of a game-engine and game-data".

game-datum (pl. game-data) A datum in a game, which is both meaningful to the player and processed by the game-engine, but which is typically not interpreted as a machine-code instruction (although it may be the operand of an instruction).


gamma-version A version that has been released to the public, typically after reaching a certain level of maturity.

Gas Synonym of Air.

ghost-conveyor A row of cells that are animated as though they were a conveyor, but which are not Conveyor-cells. In JSW48 and JSW128, a ghost-conveyor occurs in Cell-row 8 when a conveyor extends beyond the bottom-right cell. In MM and JSW64, ghost-conveyors also occur when a conveyor-animation is placed over cells that are not Conveyor-cells.


graphic An image that is drawn on the screen, consisting of a pixel-pattern and one or more colour-attributes.


guardian-class (Message 4040)

guardian-instance (Message 4040)



hacklevel A revision of the game-engine of JSW128 or JSW64 (as opposed to a revision of the game-data).

Hand of God An invisible conveyor that saves the player from danger.

hex Short for hexadecimal.

hexadecimal A number-system in which each digit is one of sixteen possible symbols: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E or F. This website uses the prefix # to indicate a hexadecimal literal, e.g. #A4C7.

HG Horizontal Guardian.

high byte The most significant byte (i.e. the upper 8 bits) of a 16-bit word. To calculate the high byte of W, divide W by 256 and round it down to a whole number. Alternatively, if W is a 4-digit hexadecimal literal, then the high byte is the two digits on the left (e.g. the high byte of #A4C7 is #A4).

high score

horizontal guardian


iff If and only if.

ILB Innocent-Looking Block.

inkless A pixel-pattern is inkless iff it has no on-pixels.

innocent-looking block

invalid arrow

invalid conveyor A conveyor whose direction-byte is a value other than 0 or 1, i.e. an off-conveyor or a sticky conveyor.

invalid ramp A ramp whose direction-byte is a value other than 0 or 1. The behaviour of invalid ramps is not yet documented, but gives rise to a new field of quirky features.

item A colour-cycling 8x8 pixel-pattern which is drawn at a particular cell in a room until it is collected. Items should not be referred to as objects, because every noun in this glossary refers to an object!

JSW A version of the game-engine from Jet Set Willy (not necessarily the original game called Jet Set Willy), excluding MM.

JSW128 A version of John Elliott's Jet Set Willy 128 game-engine, which can only run on a 128K Spectrum.

JSW48 A version of JSW that can run on a 48K Spectrum.

JSW64 A version of John Elliott's Jet Set Willy 64 game-engine, which can only run on a 128K Spectrum. There are six variants of JSW64: V, W, X, Y, Z and [.

K The suffix used in the Spectrum-community to indicate kilobytes, e.g. 48K, 128K. Some people use the suffix k instead (48k, 128k), but strictly speaking this means 1000 rather than 1024 bytes.

kamikaze To sacrifice a life to collect an item.

kill To cause the player to lose a life.

kilobyte 1024 bytes.

lateral inversion

length The number of bytes in a block of memory, or in a Spectrum-file.

life One of the number of times that the player is allowed to be killed before Game Over. In MM, an extra life is awarded for each 10,000 points; in JSW64, an extra life is awarded for collecting an item in a bonus-room.


Liquid Synonym of Water.

literal A sequence of one or more symbols representing an actual value (as opposed to a variable-name), e.g. a sequence of digits representing a number.

low byte The least significant byte (i.e. the lower 8 bits) of a 16-bit word. The low byte of W is W - 256*H, where H is the high byte of W. Alternatively, if W is a 4-digit hexadecimal literal, then the low byte is the two digits on the right (e.g. the low byte of #A4C7 is #C7).

machine-code instruction A datum that represents one of the built-in operations that a computer's hardware (or an emulator of that computer) can execute directly, consisting of an op-code and, in many cases, an operand.

'many-to-one' item

memory The place in a computer where data are stored (excluding external storage-devices such as hard disks). A 48K Spectrum's memory consists of 16K of ROM and 48K of RAM in a 64K address-space, while a 128K Spectrum uses the same 64K address-space, but can select which of two 16K ROM-banks, and which of eight 16K RAM-banks, to address at any given time.


MM A version of the game-engine from Manic Miner (not necessarily the original game called Manic Miner), excluding JSW.

mod A game based on an existing game-engine. Matthew Smith himself has used this word to describe our unofficial MM/JSW sequels!

object Anything that can be seen and/or touched - not just items, but cells, guardians, portals, teleporters, special objects and the player.

OEC Overhead Earth-Cell.


off-pixel A pixel that is 'off', i.e. drawn in the paper-colour of the character-square it's in.

'one-to-many' item

on-pixel A pixel that is 'on', i.e. drawn in the ink-colour of the character-square it's in.

op-code The part of a machine-code instruction that specifies which operation is to be executed.

opening wall

operand The part of a machine-code instruction that specifies the datum to be used in the operation.

overhead Earth-cell

overhead ILB

page A 256-byte contiguous block of memory whose start-address is divisible by 256; in other words the high byte of every address within that block, e.g. page #A6 = addresses #A600-A6FF.



pixel A picture-element; the smallest dot that the Spectrum can draw on the screen, which can either be 'on' or 'off'.

pixel-based collision-detection A kind of collision in which an object's (e.g. a guardian) pixels overlap with pixels that were drawn first.

pixel-pattern Synonym: shape


Plasma Synonym of Fire.

playing-area Everything that appears between cell-rows 0 and 15 inclusive, including the cellular layout, items, guardians and special objects.






position-based collision-detection Collision is detected based on the position of a particular object on the screen (e.g. the portal in MM, and the edges of the screen in JSW).

Promised Land

Quirkafleeg The act of lying on the ground, in the presence of small dead furry animals, kicking your legs about and shouting "Quirkafleeg!"

quirky feature

RAM Random-Access Memory: an area of memory containing bytes which it is possible to read and write, but whose values are erased when the computer is switched off. The 48K Spectrum has 48K of RAM in addresses 16384-65535 (#4000-FFFF), while the 128K Spectrum has eight different 16K banks of RAM (Bank 5 is always in #4000-7FFF and Bank 2 is always in #8000-BFFF, but any of the eight RAM-banks can be addressed in #C000-FFFF at any given time).


ramp A diagonal line of Ramp-cells.


release To make a version available to a particular audience.

revision A version that supersedes an older version.

Rigor Mortis

ROM Read-Only Memory: an area of memory containing bytes which it is possible to read but not write, and whose values are preserved when the computer is switched off. The 48K Spectrum has 16K of ROM in addresses 0-16383 (0-#3FFF), while the 128K Spectrum has two 16K ROM-banks, either of which can be addressed in 0-16383 (0-#3FFF) at any given time.





Rope-Teleport Bug



screen-layout Synonym of cellular layout.

shape Synonym of pixel-pattern.


solar power

Solid Synonym of Earth.

special edition

special object

Spectrum-file One of the files on a tape (or encoded within a TAP file or a TZX file), consisting of a header-block followed by a data-block, and being of one of the following types: a BASIC program, a contiguous block of bytes (specified by CODE start-address, ), a number-array or a character-array.

speed How fast something moves, in pixels per time-frame.

springy platforms An effect achieved by giving Air the same colour-attribute as Ramp, which affects the stand-onable cells in the room.

sprite An image, possibly animated, that is drawn on the screen, consisting of a pixel-pattern for each sprite-frame of animation. Colour-attributes are not considered part of a sprite (contrast with graphic).

sprite-frame One of a sprite's pixel-patterns, used in the context of animation. Each sprite has either 1, 2, 4 or 8 frames, depending on the animation-mask and the start-frame.


Stair (Message 5357)

start-address The address of the first byte in a block of memory.

start-frame An initial sprite-frame. In MM, each room specifies a start-frame for Willy, and for each vertical guardian. JSW doesn't specify any start-frames, not even for Willy's global start-position.

stand-onable Able to be stood on by the player. This applies to all cells except Air, Fire and Trap (the player will fall into a Fire- or Trap-cell even if also standing on a stand-onable cell). Ropes and Lifts are two kinds of stand-onable guardian.

Static Nasty Synonym of Fire.

static POKE A poke that has to be applied before you start playing the game - before you even reach the title-screen.

sticky conveyor

Synonym A term with the same meaning as another term.








transformation A variant that results from applying a transformation-algorithm to another variant.

transformation-algorithm A variant that results from applying a transformation-algorithm to another variant.

trigger A JSW64 guardian-type that watches a byte of memory until it becomes zero, and then changes bytes in the next guardian in the room's guardian-list.

ultrafast VG

unidirectional HG A horizontal guardian which goes left and right, but only using the sprite-frames from one half of its sprite-page.

vanishing wall Synonym of opening wall.

variant A version that exists in parallel with other versions, rather than superseding them.

velocity The speed of an object, together with its direction.

version A particular form of something (e.g. a game) that differs from any other versions of that thing that may exist.

vertical guardian

VG Vertical Guardian.

Wall Synonym of Earth.

Water A cell-type that the player can stand on, and move through in all ways except falling. Synonyms: Floor, Liquid. Does not necessarily represent water!

wraparound guardian

Willy The player.

Email me
Hosting by WebRing.