The GUI presented by VirtualH89.jar provides some useful features for operating the system.
There are two menus available, "System" and "Disks".
"Disks" provides one way to view and change what images are mounted on floppy (removable) drives. The menu will show something like:
MMS77316-5 [cpm2disk5.logdisk] MMS77316-6  MMS77316-7  MMS77316-8  Refresh
Which shows that there are 4 drives in the system capable of mounting (floppy) images, they are drives 5-8 (the 5.25" drives) on the MMS 77316 Double Density controller. The first of those drives (#5) has an image mounted on it, named "cpm2disk5.logdisk".
Choosing "Refresh" will refresh the list of disks and media with the core H89, in case they have gotten out of sync.
Choosing one of the disk drives will pop up a file selection dialog to allow changing out the media in that drive. Clicking "Cancel" will leave the drive/media as it currently is, but there is an checkbox titled "Unmount" that can be used, in conjunction with the Cancel button, to remove any current media from the drive (i.e. make the drive "empty"). There is also a checkbox for "Protect" that will mount the media "Read Only" or write-protected. This is equivalent to using the notch/sticker mechanism on real floppies of that era.
"System" provides basic control and debugging of the virtual machine. Typical options will be:
Screen Dump Trace (custom) Trace ON Trace OFF Dump To Log Dump CPU Dump Machine Dump CON_INS8250 Dump MMS77316 Reset Quit
Your System menu may contain more or less "Dump" items, depending on the hardware configuration.
"Screen Dump" will print a copy of the current CRT screen text to the system log, etiher "standard error" of the process running Java or a log file if that was configured. Trailing blanks on each line are removed, and the screen data is bounded by lines of "-------...-------".
"Trace" options will cause the CPU to start outputting trace line for every instruction executed by the Z80. Use caution as this not only fills the log file or terminal window very quickly, but also slows down the simulation considerably. The "(custom)" option is probably the most useful. It pops up a dialog where you can enter a number of clock cycles to trace (2.048MHz clock), a range of addresses, or a number of seconds (default is for "1" second, which still produces a lot of data).
"Dump" options will gather useful information from the respective "hardware" component and display it in a pop up window. The option "Dump To Log" will switch the dump output to the system log (as described above), and will then appear as "Dump To GUI" to switch back to dumping in pop-up windows.
"Reset" is the same as Shift + F9 (standard SHIFT/RESET sequence on an H19).
"Quit" will terminate the virtual system.
On the right-hand "nameplate" section of the system there will be labeled LEDs for each drive. Drives that allow removable media (i.e. floppies) will show a slight change of color as the mouse pointer hovers over them. Clicking on such a disk drive will pop up the same dialog available in the "Disks" menu.
Disk activity is indicated by the associated LEDs, simulating the LEDs on real disk drives of the era.
Hardware is configured using a small text file, which by default is expected to be ".v89rc" in your home directory. The environment variable "V89_CONFIG" may be used to specify a different confdiguration file.
The file uses lines of the format "property = value". Other help documentation for respective hardware describes applicable properties.
If no configuration file is found, the base hardware consisting of 48K RAM, MMS 444-84B Monitor ROM, and (only) the Console serial port will be used. The machine is functional enough to only run the monitor, but will demonstrate the basic machine.