Does anyone have a ET4000 and/or ET4000/W32(or ET4000/W32i, but not ET4000/W32p) card and is willing to verify if those registers are readable when the KEY isn't set?

The emulators themselves seem to all go against documentation on that (Dosbox, 86box, PCem, PCem-X)? Of course, the PCem-X are the worst of all(no protection and KEY is implemented AT ALL!).

The most simple test would be to display any value read from one of the protected registers while they KEY isn't set and display it's value read in hex(store as variable #0), then set the KEY, backup the original value of such an register (store as variable #1), write a value with (partly if otherwise unsafe according to documentation) inversed bits to the register(new value stored as variable #2), disable the KEY, store the value now read from the register (store as variable #3), set the KEY again, write the variable #1 back to the register, disable the KEY.
Finally just print (in hex, in 2 hex digits for each variable) variables #0, #1, #2, #3 in that order.

I've placed a simple program(only run this on a ET4000 or compatible chip!) in the UniPCemu's repository, in the assembly folder to show how the 6845 compatiblity register is affected(non-destructive, just toggling bit 3 which should be safe on the Tseng chips).

Dosbox SVN Daum reports 00000800 on the ET4000 chipset (meaning that it's original 00h, 00h with KEY, 08h written with KEY(bit 3 has been toggled, which should be safe) and 00 read back without KEY after that).

I've compiled it using nasm into a working .com program.

Anyone willing to run this on their ET4000 or ET4000/W32i and report the results that it gives? And with that I mean actual barebones hardware, not an emulated one (unless confirmed exactly the same as actual hardware).

Although ideally, I would want it's results on all ET4000 chipsets(ET4000AX, ET4000/W32, ET4000/W32i and ET4000/W32p) for exact documentation and implementation of course (that would also benefit other emulators actually implementing those W32i/W32p chipsets).

It's source code can be found at the UniPCemu repository ( https://bitbucket.org/superfury/unipcemu/src/ … 0protection.asm ).

A slight bugfix of the app:

Eventually found a lot more bugs in the last version:

It fixes quite a lot of little bugs:
- Code and data segment are the same.
- Put the graphics card in color mode always.
- Added a hex display of the data read back after writing the toggled bit to register 34h.
- Simplified CRTC register reading code.
- Properly write the register instead of reading it when requested to write it.
- Fixed clearing of the KEY to clear it correctly according to documentation (was reversed registers and wrong value to the mode control register).
- Fixed values A-F hex display to be calculating the character code correctly.

Another needed update with the bugfixes it needs:

- Save flags as well during program execution.
- Assume .COM CS=DS
- Properly restore the Tseng modifed CRTC register at the end of the tests.
- Newline after each outputted byte of the results for ease of readability.
- Fixed clearing of the Tseng KEY to properly setup it's registers to do so (instead of writing to wrong I/O ports in DX).
- Simplified 4-bit hex printing function.
- Seperated CRLF printing into a function.