Changes in release 1.9:
The update to release 1.9 can be easily done with the program ZXMORE19.P in the same way
like the update to release 1.7 or 1.8 (see section 1.7 for more details). The update can be
done either from version 1.7 or 1.8 directly.
From release 1.8 you may use not just one address
line like A7,A6.A5,A4 or A3. If required you may
combine several or address lines and enter a specific
io address which can be entered with a leading zero.
The actual used io address is required as well as the
possibly new (changed) address. Every time you want
to change the io address you have to use the update
utility ZXMORE19.P and do a new update as the
address has to be patched in several rom addresses
and could not be determined automatically during
start.
Multitasking Mode
New in release 1.9 is the multi tasking mode which allows parallel execution of several
instances at the same time (quasi-parallel). The screen of the foreground task is displayed and
gets the keyboard input while all background tasks run without display and keyboard input.
Multi tasking mode can be switched on and off with DS-M (toggle mode). Switching on is
possible only if more than one instance is running. The foreground instance gets always 50%
of cpu time while the other instances share the other 50% of cpu time while they are executed
in a round-robin manner. The foreground task is executed always in the top margin while all
other instances are executed in the bottom margin. Background tasks change every frame.
When running 2 instances, all background task get 50% cpu time, when running 3 instances
this will result in 25% and with 4 instances in 16.5% and so on. A specific configuration is not
possible wether necessary. Multi tasking can be switched off any time with DS-M (double shift-
M). Additional it's possible to change the active foreground instance with DS-1 to DS-7 while
running multi tasking mode to maybe proof the progress of any background task.
There are following restrictions for the multi tasking mode:
* only running with PAL (no NTSC)
* only with RAM mirror set (max. 32k RAM) or CPLD version 06/2016
* only text is displayed (no HRG)
* frame counter does not correspond to time or frames elapsed
Multi tasking is not reliable with NTSC display and may result in instance crash due to strong
timing requirements. If many or fast changes from FAST to SLOW and back there may be also
crashes possible. This can be prevented with reducing memory to 32k RAM while turning RAM
mirror on or with a newer CPLD (version 06/2016). Choosing RAM mirror is a reliable
workaround. The reason for this behaviour is the video mode detection necessary during video
display and A15 handling together with the extended M1 NOT mode over the complete address
area. There maybe situations in FAST mode where video display is not detected and reading
DFILE from the upper 32k instead of the lower 32k.
Due to technical reasons only text display is shown during multi tasking mode. Programs with
high resolution graphics can be run but the result in the display is not shown. A suitable work
around is to temporarily switch off this mode with DS-M, check the graphics content and
continue multi tasking again with DS-M.
V1.9 - 06/2016
ZXmore & ZXmaster – user manual
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