Weiss jemand endlich mal auf diesen brett was die meldung heisst "Steuerung der A-20 leitung nicht möglich XMS treiber nicht installiert" das bei komplett neu installatio von WIN 98.Ich dachte hier gibts nur profis,aber seit einer woche suche eine antwort!!!!!!!!!!! ((Anonym))
Antwort:
also, 1. gibt hier vor allem nicht-profis, die rat bei ein paar wenigen profis suchen.
2. such im archiv nach "A20"
3. versuche im BIOS die "Defaults" zu laden. (der tip stand u. a. im archiv)
leider fehlt hier ein wirklich wahrer profi (war n schweitzer, weiss nicht mehr, wie er sich nannte), der konnte dir sicher antworten.. nach meiner 1-jahrigen pause hab ich ihn nicht mehr hier gesehen.
ich werd mich mal informieren, was es mit der Leitung "A20" auf sich hat, es kann nämlich sein, dass sie auf einen hardware-fehler hinweist. (KANN!, muss nicht)
Gruss,
dP
((Anonym))
Antwort:
Was Intel meint:
High Memory Area (HMA)
HMA refers to a specific way of accessing the first 64Kb of Extended
Memory. Normally, for an 80286 to access extended memory, the
processor has to switch into what is called "protected mode", make the
extended memory access, and then be reset so that it returns to "real
mode" (which is the mode that DOS runs under). This whole operation
takes time. There is, however, a "back door" method to access the
first 64K of extended memory without switching the processor into
protected mode. What manages this special way of accessing the first
64K of extended memory is something called an HMA provider (also
sometimes called an A20 handler).
***
woanders gefunden:
This option uses the fast gate A20 line, supported in many chipsets, to access the memory above 1 MB. Using this option will make the memory access faster than
when this setting is not enabled. This option is very useful in networking and multitasking operating systems.
***
wo anders wiederum:
(or Turbo Switch Function) determines how memory gate A20 is used to access memory above 1 Mb, which is
usually handled through the keyboard controller chip (the 8042 or 8742).
The 8088 in the original PC would wrap around to lowest memory when it got to 1 Mb. The 286 would wrap
around at 16 Mb, as it had more address lines. To allow older programs to operate, an AND Gate was
installed on CPU address line 20 that could switch to allow either wraparound to 1 Mb or access to the
16 Mb address space. A spare pin on the keyboard controller was used to control the gate, either through
the BIOS or with software that knew about it (the keyboard controller is a computer in its own right,
and it had some spare programming space as well as a spare pin that could be used for stuff that was
left out of the 286).
Programs such as Windows and OS/2 enter and shut down through the BIOS, so Gate A20 needs to be
continually enabled and disabled, at the same time as another command to reset the CPU into the required
mode is sent.
Enabling this gives you the best Windows performance, as a faster method of switching is used in place
of using the (slower) keyboard controller, using I/O ports, to optimise the sending of the two commands
required; the Fast Gate A20 sequence is generated by writing D1h to port 64h, and data 02h to port 60h.
The fast CPU warm reset is generated when a port 64h write cycle with data FEh is decoded.
You will notice very little difference if all your programs operate inside conventional memory (that is,
under DOS). However, this may cause Multiuser DOS not to boot. If you get keyboard errors, enable this.
One problem can occur with this option in AMI BIOSes dated 2/2/91 and later; it doesn't always work with
the DOS 5.00 version of himem.sys. If you get an error message, disable this setting. If the error
persists, there is a physical problem with the Gate A20 logic, part of which is contained in the
keyboard BIOS chip, in which case try changing this chip.
This is nothing to do with the Turbo switch on the front of the computer; The alternative heading could
be Turbo Switching Function.
und...
As for Fast Gate A20 Option,
