Objective-C Z80 Exceltronix Multiflex Super System emulator screenshot

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A screenshot of my Z80 Exceltronix Multiflex Super System emulator

The top left window is the Z80 emulator. It shows the current contents of the active registers as well as the programme counter and stack pointer. The second set of registers is also shown to the right in grey. The ability to set two breakpoints is included and their addresses are shown (both addresses blank in this image). Below the registers is shown the next instruction in both machine code and assembler code and below this is a place where error messages are displayed such as for invalid opcodes. Below this are displayed 32 bytes of memory at the address requested. At the bottom of the window is a field in which one can set the speed of emulation to any speed between 50 and 10,000 instructions per millisecond (i.e. 50,000 to 10,000,000 instructions per second). At 10,000,000 instructions per second the emulator runs my MacBook Pro at about 50% CPU. A Z80 microprocessor chip running with a 4 MHz clock might run, say, 500,000 instructions per second so the software emulator is considerably faster. Finally, the window contains buttons to single-step the instructions or to run continuously.

The bottom left window is the Exceltronix Multiflex Super System emulator. It shows the six red LED 7-segment displays with the two keypads below. At the bottom is a button for resetting the CPU.

The right-hand window is the floppy disk drive and screen emulator. At the top are four emulated drives which are loaded with emulated floppy disks using the Load buttons. The disks are emulated with Macintosh files but changes made to the disks are not immediately written to the files. Instead, new data is saved to the file when the disk is ejected with the Eject button. However, at any time, data can be saved to the file using the Save button. Below the disk drives is the screen emulation which, in this image, has CP/M loaded and showing the a> prompt. The reference to CPM version 2.2J35 denotes Digital Research version 2.2 with my subsequent updates: 3 to the BIOS and 5 to CP/M itself. Finally, at the bottom of the window, are buttons that bring up a file dialogue box to allow the loading of a hex, machine code or text file into the transient program area.