The only description of the effects of "program reset" in the original MOS
datasheet is in the section for each register. The W65C51S and W65C51N
datasheets have a heading "PROGRAM RESET OPERATION", but it amounts to:
- internal registers are modified as described in the section for each register
- changes to the DTR, DCD, and DSR pins which Symon does not emulate
- the overrun flag is cleared
...which is what this new implementation does.
It would make *sense* for the reset to do things like "cancel transmission or
reception in progress" and stop asserting an interrupt, as the old code did,
but I can't find any evidence of such behaviour in the datasheets.
When describing the CPU's reset pin, the W65C02S data sheet says:
> All Registers are initialized by software except the Decimal and Interrupt
> disable mode select bits of the Processor Status Register (P) are initialized
> by hardware.
It then has a diagram of the power-on state of the processor status register:
> 7 6 5 4 3 2 1 0
> * * 1 1 0 1 * *
> N V - B D I Z C
>
> * = software initialized
Confusingly the text indicates that only the D and I flags are initialised by
hardware, while the diagram indicates that the B flag is initialised too.
Meanwhile, https://www.nesdev.org/wiki/CPU_power_up_state says that
the power-on state of the NES CPU is $34 (exactly matching the diagram above)
but https://www.nesdev.org/wiki/Status_flags#The_B_flag says that the B flag
does not physically exist within P register, it's only relevant in the copy
of P that gets pushed to the stack by BRK (set), PHP (set), or an interrupt
signal (cleared).
As a result, the most sensible power-on state for the processor status register
is with the "interrupt disable" flag set and everything else cleared.
A bug caused the video window to repaint only when the cursor was
blinking. This meant that if the cursor was disabled, the window would
never update!
This change removes the repaint logic from the cursor blinking timer,
and instead puts it into its own periodic timer callback that runs
independently of cursor blink.
* On Linux GTK+, the small text fields in the Status Panel displayed a
large inner margin, cutting off text. This change forces Java to use the
Metal look-and-feel for these fields, which forces no default inner
margin.
* Fix ACIA6850 Interrupt behavior, Interrupt should be cleared on status register read.
* Remove unneeded cpuAccess if statement from Acia6850 write that was preventing build completion
* Fix ACIA6850 Tests so they run.
Tim Allen