Scroll down to find the sprites defined in binary, look close enough to see them hiding between the zeros and ones. Have you played them all? The Chuckie Egg Collection https://scratch.mit.edu/studios/32062422 Retro Style Text File Viewer Remix Instructions: Remix to display your own text files. Simply import a text file into the list CH_EGG.6502. Rename the list to your file name. Importing text files in Scratch can be tricky. Comma (,), semicolon (;) and double quote (") can cause strange behavior. One option is to replace these characters with other characters. E.g. replace comma (,) with pound (£), import, then replace pound (£) with comma (,). There are scripts provided to replace these characters at the bottom of the Text Viewer sprite. In fact, to import a list in scratch without errors the import file should be in a single column CSV format, which can be generated from most spreadsheet applications.
Chuckie Egg Source Code (BBC Micro version) Chuckie Egg by Doug Anderson © A&F Software 1983 BeebASM source file by Rich Talbot-Watkins The font is BBC Mode 7 (Teletext) borrowed from @RokCoder's awesome Beeb Emulator. This code is provided for reference only. It is an interesting example of a simple game written in BBC Micro style 6502 assembly language. This source file was used in the development of Scratch version of Chuckie Egg. The code is well commented however an explanation of assembly language is beyond the scope of this project. In 1983 to make a computer game fast enough to enjoy it was necessary to write it in assembly language and compile it to machine code. Fortunately, modern computers are much faster, and this is no longer the case. Assembly Language is an advanced topic way beyond the scope of a typical Scratch project. That said understanding assembly language helps to understand how the computer works at the lowest level. The 6502 is an 8-bit microprocessor, there are 56 instructions and 6 registers. Each instruction acts upon one or more of the registers. A register is like one byte of memory inside the microprocessor. In 6502 assembly language each instruction is represented by a 3-letter mnemonic. In its simplest form we can think of a computer as a microprocessor (that does the work) and memory (that stores the data). The microprocessor loads data from memory into a register, performs one or more operations on the register and stores the register value in memory. The 6502 contains six registers. accumulator (A) - Handles all arithmetic and logic. X and Y - Index Registers P - Processor Status. Holds the result of tests. S - Stack pointer. PC - Program Counter (16-bit). Holds the memory address of the next instruction to be executed. In addition the assembler allows us to define labels, provides helpful directives and write comments. In the BeebASM code we see: labels start with a full stop(.), assembler directives SKIP, EQUB, EQUW and EQUS, comments are preceded with a semicolon(;). Simple Example .score SKIP 8 ; assign label to current address and reserve 8 bytes. This is similar to creating a new variable in Scratch. ; Set score to 0 LDA ; Load value zero into the accumulator register STA score ; store the value of the accumulator register into the score variable ; Change score by 1 LDA score ; load the score variable into the accumulator register INC ; Increment (add 1 to) the value of the accumulator register STA score ; store the updated value of the accumulator register into the score variable ; EQUB, EQUW and EQUS Insert the specified byte(s) into the code. ; the sprite_egg label points to 8 bytes of data that make the egg. .sprite_egg EQUB %00000000 EQUB %00111000 EQUB %01101100 EQUB %01011110 EQUB %01111110 EQUB %01111100 EQUB %00111000 EQUB %00000000 Further reading: https://dwheeler.com/6502/oneelkruns/asm1step.html A reference for the 6502 opcodes: http://www.6502.org/tutorials/6502opcodes.html BeebASM assembler directives: https://github.com/stardot/beebasm A simple introduction from the Acorn Electron User Guide (very similar to the BBC Micro): http://www.acornelectron.co.uk/ugs/electron/acorn_computers/ug-english/chapter029_eng.html To study this file further it is recommended to export the list CH_EGG.6502 and view in a modern text editor.
