Source Codes

This article contains source codes and programming examples. You may also have a look at

• Programming software
• BIOS Functions
• Technical documentations
• Locomotive BASIC
• Type Ins

• Z80 - undocumented opcodes
• Where to learn?

• Bubble sort
• CPC OS floating point routines
• CRC16
• CRC32
• Integer Division
• Integer Multiplication
• Logarithm
• Ultrafast Multiplication by Prodatron
• Fast Square Root
• Fast 16 bit Square Root by Executioner
• Filling memory with a byte
• Square Root
• Precalculated square
• Random Number Generator
• Reverse A
• Quicksort
• Sin/Cos calculation

• A simple 'Hello World' program for CP/M using BDOS
• A simple 'Hello World' program for CP/M using BIOS
• Executing firmware functions from within CP/M 2.1
• Executing firmware functions from within CP/M 2.1 or CP/M plus
• Executing firmware functions from within CP/M 2.1
• Executing firmware functions from within CP/M plus

• Amstrad CPC plus sprite format
• Convert CPC sprites to Plus hardware sprites
• Sprites Multiplexing
• Hardware sprites
• Horizontal scroll
• RLE hardware sprites
• Screen splitting
• Vertical scroll
• Operation of Z80 interrupt mode 0 in the CPC plus design
• Simple Raster Example 1 (uses CPC plus features)
• Simple Raster Example 2 (uses CPC plus features)
• Unlocking ASIC

• CPC Booster
• Digiblaster
• Program to save the ROM of the Multiface 2
• SYMBiFACE II

• An example to read a file byte-by-byte
• An example to write a file byte-by-byte
• A simple file copier using firmware functions (copies byte-by-byte)
• Loading a file
• Saving a file
• Unlocking a protected basic file
• Undo delete of file

• A simple disc copier using BDOS functions
• A simple disc formatter using BDOS functions
• An example loader
• Catalog a disc and retrieve a directory
• Detecting an Amstrad or Vortex disc controler
• Formatting a track on a disc
• Reading a sector from a disc
• Reading and writing the boot sector of a SYSTEM/VENDOR disc
• Writing a sector to disc

• Display a 8-bit number in binary
• Display a 8-bit number in hex
• Display a byte as a 3-digit decimal number
• Display and update Scores
• Distorting the screen using register 2 of the CRTC (Horizontal Sync Position)
• Fast plot
• Fast Sprites by Executioner
• Fast Textoutput by Prodatron
• Hardware Scrolling by Executioner
• Hardware Scrolling 2
• Hardware scrolling the screen horizontally byte-by-byte using the CRTC
• Hardware scrolling the screen using the CRTC
• Next / previous line calculation
• Overscan
• Plotting a sprite using character matrices
• 4th Mode of CPCs: Plotting sprites on 2 bitplanes
• Set the screen refresh rate
• Simple Raster Example
• Simple Split Raster Example
• Synchronising with the CRTC and display
• CRTC change colour (fill) test with precise timing by Matahari
• 256 byte Overscan MEGATEXT Intro - (features 50Hz fullscreen scroll) by Matahari

• Reliable use of interrupt mode 2 on the CPC

• Keyboard scanning

• An example boot sector (executed with rsx command CPM)
• An example to define a RSX
• Calling a RSX from outside of BASIC
• Dumping the data of BASIC or AMSDOS or an expansion rom
• Dumping the data of the lower rom

• How to access the PSG via PPI
• Tutorial - Understanding the fundamentals of BASIC SOUND and the Firmware SOUND QUEUE
• Source code to show 0x0ff is always returned when reading PSG port B
• Source code to show it is possible to store data in PSG register 14 and 15 (port A and port B)
• Source code to show it is possible to store data in PSG register 14 and 15 even if the port has been set to input
• Source code to show that some registers always return 0 in some bits
• Source code to show that when a port is read in output mode; the data read will be ANDed with the inputs to that port

• Cross Development

• Memory range for programs is &0040-&a700. This avoids firmware and memory allocated by AMSDOS disc ROM.
• Programs on cassette and disc have a header that define the load address, length and execution address.

In Pasmo assembler use the "end" mnemonic to define the label which is the execution address and use "--amsdos" to put an AMSDOS header on it.

• Basic programs start at &170.
• Firmware uses interrupt mode 1 of the Z80 (interrupts jump to &0038)
• Lowest place you can LOAD a binary file to with BASIC is &389 e.g.:

openout"d"
memory <address>-1
closeout
load "code",<address>
call <exec>

• Screen is normally at &c000-&ffff. (It can be changed using firmware, or using CRTC R12/R13)
• Stack is normally at &c000 and goes down.
• Extra registers (BC', AF', HL', DE' are reserved by the firmware). Avoid if you are using firmware functions.
• Lower rom (containing OS) can be paged into memory between &0000-&3fff.
• Upper rom is selectable, examples are BASIC and AMSDOS. They can be paged into memory between &c000-&ffff.
• From basic, a game is run with:

RUN"<filename>

keep it in the safe memory ranges and it'll run from cassette and disc.

• Screen is normally 40 crtc chars wide (CRTC R1=40), 25 crtc chars tall (CRTC R6=25). 8 scan lines per char (R9=7). Firmware functions assume this.
• Screen is bitmapped. You must draw/erase your own sprites and text.
• Firmware refreshes the palette every 50th of a second, so you need to turn off the firmware and use the hardware directly, or set the colours using firmware.
• Firmware can be "turned off", by disabling lower ROM, redirecting interrupts and not calling firmware functions.