Hello Egor,
The external mapper I use DOES support read-back. In a MSX2 it works just fine...
Even with more than one mapper...
And as a result of the problems in a turbo-R, more people have found out that there
is a problem with mapper readback of the S1990... And it seemed to be that
the origin of this problem is the one that's mentioned several times on this list.
Greetings from Erik Maas
----------
From: Egor Voznessenski
Sent: Wednesday, May 27, 1998 2:27 PM
To: [EMAIL PROTECTED]
Subject: Re: Looking for Ram (turbo-R with S1990)
> Now to the point with an external mapper, all the higher bits are read as one :
>
> e.g.
>
> Internal 512 Kbyte mapper
> External 2048 Kbyte mapper
>
> out &hfe,1
> in &hfe -> &b11100001
>
> This is with and without the external mapper!
> I could be wrong, but I think with a 256 kbyte turbo-R ST even bit 4 will be high.
> By adding a pull-up to a certain pin, the engine can be configured at power-up.
The point here is:Does this external mapper support read-back? As far as I understand
many
of the extensions
don't support reading of their mappers (for example AddRam, if the circuit diagram of
it
that I found on the Net is correct)
> The engine wins the battle of the higher datalines because in series with the
>datalines
> from the processor(s) to the cartridge connectors there are resistors.
> (I think they are 100 ohm)
Probably you are right here. (however 100 ohms seems a slightly bigger value than
usual 22
or 33 ohms)
application/ms-tnef
