PROFI INTERFACE use one port #EF for change configurations. But +D use same port for select drive:
+D Control, port 239=EF
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bit 0 = drive 1
bit 1 = drive 2
bit 6 = strobe (printer)
bit 7 = side
+D is incompatible with PROFI interface. But is not so big problem change PROFI port to any other. After change PROFI port must be also rewrited port in main menu and in FLASHER utility.
About timing:
PROFI can't change screen timing or interrupt position. With PROFI work ula identically, but memory contention out of both videorams is disabled (slow ram pages run at full speed). Also I/O ports are uncontended.
With profi interface you can:
- set original ZX128 mode (with all bugs as screen raining, contended memory,, all known bugs, etc...)
- set ZX128 mode with fixed raining effect, without bugs, with or without contended memory, etc...
- set Pentagon 128 or 1024kB mode (Pentagon 128 is more compatible with ZX128 software)
- set ZX PROFI 1024 mode - this mode best.
- set ZS SCORPION 1024 mode - compatibility with russian SCORPION memory paging.
For run russian software with critical timing I use mode ZX PROFI + you must active "FAST" in main menu for disable memory contention and speed-up I/O ports.
For each mode you can use your own zx rom (can be reflasher via FLASHER utility).
You can in BASIC active via OUT 1007,1 turbo mode (at 3.5MHz but without memory contention-only videoram is slow). And OUT 1007,0 = original ZX128 timing.
All modes PENTAGON,PROFI and SCORPION use same timing, only memory paging port is different.
