rzxplay.py¶

SYNOPSIS¶

rzxplay.py [options] FILE [OUTFILE]

DESCRIPTION¶

rzxplay.py plays an RZX file. If ‘OUTFILE’ is given, an SZX or Z80 snapshot or an RZX file is written after playback has completed.

OPTIONS¶

-c, --cmio: Simulate memory and I/O contention delays and the MEMPTR register.
--flags FLAGS: Set playback flags. Do --flags help for more information, or see the section on FLAGS below.
--force: Force playback when an unsupported machine is detected.
--fps FPS: Run at this many frames per second (default: 50). 0 means run at maximum speed and update the screen 50 times per second. A negative value (-N) means run at maximum speed and update the screen N times per second.

-I, –ini param=value: Set the value of a configuration parameter (see CONFIGURATION), overriding any value found in skoolkit.ini. This option may be used multiple times.

--map FILE: Log addresses of executed instructions to a file.
--no-screen: Run without a screen.
--python: Use the pure Python Z80 simulator even if the C version is available.
--quiet: Don’t print progress percentage during playback.
--scale SCALE: Scale the display up by this factor (default: 2).
--show-config: Show configuration parameter values.
--snapshot FILE: Specify an external snapshot file to start with.
--stop FRAMES: Stop after playing this many frames.
--trace FILE: Log executed instructions to a file.
-V, --version: Show the SkoolKit version number and exit.

SUPPORTED MACHINES¶

rzxplay.py can play RZX files that were recorded in 48K, 128K or +2 mode with no peripherals (e.g. Interface 1) attached. If any peripherals are attached, playback may fail. The --force option can be used to make rzxplay.py attempt playback of a file that was recorded on an unsupported machine, but it is unlikely to play to the end.

SCREEN¶

If pygame is installed, rzxplay.py will use it to render the Spectrum’s screen contents at 50 frames per second by default. Use the --fps option to change the frame rate. Specifying --fps 0 makes rzxplay.py run at maximum speed. To disable the screen and make rzxplay.py run even faster, use the --no-screen option.

CODE EXECUTION MAP¶

The --map option can be used to log the addresses of instructions executed during playback to a file. This file can then be used by sna2ctl.py to produce a control file. If the file specified by the --map option already exists, any addresses it contains will be merged with those of the instructions executed.

FLAGS¶

The --flags option sets flags that control the playback of RZX frames when interrupts are enabled. If an RZX file fails to play to completion, setting one or more of these flags may help. FLAGS is the sum of the following values, chosen according to the desired outcome:

1 - When the last instruction in a frame is either ‘LD A,I’ or ‘LD A,R’, reset bit 2 of the flags register. This is the expected behaviour of a real Z80, but some RZX files fail when this flag is set.
2 - When the last instruction in a frame is ‘EI’, and the next frame is a short one (i.e. has a fetch count of 1 or 2), block the interrupt in the next frame. By default, and according to RZX convention, rzxplay.py accepts an interrupt at the start of every frame except the first, regardless of whether the instruction just executed would normally block it. However, some RZX files contain a short frame immediately after an ‘EI’ to indicate that the interrupt should in fact be blocked, and therefore require this flag to be set to play back correctly.
4 - Ignore any snapshots after the first one. By default, rzxplay.py will use a snapshot embedded in an RZX file to update its internal state (i.e. memory and registers) before continuing to process the next input recording block. However, some RZX files created by the Fuse emulator do not play correctly under that scheme, and require this flag to be set.

OUTPUT FILE¶

If OUTFILE is given, and ends with either ‘.z80’ or ‘.szx’, then a snapshot in the corresponding format is written when playback ends. Similarly, if OUTFILE ends with ‘.rzx’, then an RZX file is written when playback ends. However, this makes sense only if --stop is used to end playback somewhere in the middle of the input RZX file, otherwise the output RZX file will be empty (i.e. contain no frames).

CONFIGURATION¶

rzxplay.py will read configuration from a file named skoolkit.ini in the current working directory or in ~/.skoolkit, if present. The recognised configuration parameters are:

Screen:

Display screen contents while running (1, the default), or don’t (0).

ScreenFps:

Screen refresh rate in frames per second (default: 50). If set to 0, run at maximum speed and update the screen 50 times per second. If set to a negative value (-N), run at maximum speed and update the screen N times per second.

ScreenScale:

Screen scale factor (default: 2).

TraceHeader:

The header to write in the trace log file (default: None).

TraceLine:

The format of each line in the trace log file (default: F:{fr:0{fw}} C:{fc:05} I:{rr:05} ${pc:04X} {i}).

TraceOperand:

The prefix, byte format, and word format for the numeric operands of instructions in the trace log file, separated by commas (default: $,02X,04X). The byte and word formats are standard Python format specifiers for numeric values, and default to empty strings if not supplied.

TraceLine is a standard Python format string that recognises the following replacement fields:

fc - opcode fetch counter
fr - frame number (0-indexed)
fw - maximum width required for the frame number field
i - the current instruction
m[address] - the contents of a memory address
pc - the address of the current instruction (program counter)
r[X] - the X register (see below)
rr - the number of input readings remaining in the frame
t - the current timestamp (in T-states)

When using the m (memory) replacement field, address must be either a decimal number, or a hexadecimal number prefixed by ‘$’ or ‘0x’.

The register name X in r[X] must be one of the following:

a b c d e f h l bc de hl
^a ^b ^c ^d ^e ^f ^h ^l ^bc ^de ^hl
ix ixh ixl iy iyh iyl
i r sp memptr

The names that begin with ^ denote the shadow registers.

Wherever \n appears in the TraceHeader parameter value, it is replaced by a newline character.

Configuration parameters must appear in a [rzxplay] section. For example, to make rzxplay.py write instruction addresses and operands in a trace log file in decimal format by default, add the following section to skoolkit.ini:

[rzxplay]
TraceLine={pc:05} {i}
TraceOperand=

Configuration parameters may also be set on the command line by using the --ini option. Parameter values set this way will override any found in skoolkit.ini.

EXAMPLES¶

Play game.rzx:

rzxplay.py game.rzx

Log the instructions executed while playing game.rzx:

rzxplay.py --trace game.log game.rzx

Play only 100 frames of game.rzx and then write game-100.rzx:

rzxplay.py --stop 100 game.rzx game-100.rzx