I have asked Johan Koelman to give more information to the SAM<>PC interface, you will see below. Just a comment from me, as it was asked too: The interface works without problems with a SAM and Atom harddisk (two decvices), PC keyboard interface, PC mouse interface, SAMclock and also Quazar surround, as this is my combination.
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Replies on questions from Johan Koelman.
Speed of ZX-PC Interface:
This interface uses the parallel port. It sents 5 bits of data everytime (4 data + 1 signal bit). A byte is also sent in 2 loops. The interface was built for the ZX Spectrum, but someone suggested to use it for the SAM. Instead of building an interface with a SAM-connector I just made a connector to go from SAM to Spectrum since this user already had a ZX-PC Interface (yep Johan, it was me ;-).
It loads a complete 48K block in less than 8 seconds, which comes to approximately 49152 Baud.
The ZX-PC Interface has an external Eprom for using the normal tape-commands to point to the PC. On the PC a serverprogram runs to load/save data. Some extra routines in the EPROM makes it possible to select other drives like diskette or CD-ROM.
For the SAM only the LOAD/SAVE interface is built. The eprom was detected, but wouldn't run directly (I don't know too much about the SAM to solve it directly, so the eprom was de-activated).
For the Spectrum the storage is in TAP-files and loaded can be done from TAP/Z80 en SNA-files.
Sizes of the interfaces
The ZX-PC interface is built inside a cassettebox. I used a cigarbox for the SAM-interface due to the larger connector, otherwise it would have been built inside a cassettebox as well.
The SAM-to-Spectrum-connector is built inside a cigarbox due to the size of the external connector. Not only did I connect all Spectrum connectors to the right possition, but also added all SAM-connections outside the spectrum connections, something like this
SSSZZZZ#ZZZZZZZZZZZZZ
SSSZZZZ#ZZZZZZZZZZZZZ
S=SAM
Z=Spectrum
#=Spectrum block in connector
Theoraticcaly I already told that other devices could be connected. The Kempston interface proved it. For those interested I have the scheme for the ZX-PC Interface at:
http://www.worldofspectrum.org/forums/viewtopic.php?topic=1899&forum=4
The software is already sent to Stephan Haller to make it work for the SAM.
Johan "Dr Beep" Koelman
Prices:
The SAM-PC Interface is nothing more than the standard IO-interface. It uses 4 chips.
7404 Invertor 0,90 €
7427 Triple NOR 0,90 €
74245 or 74244 Buffer for read 1,00 €
74373 or 74573 Buffer for write 1,00 €
1 25-pin connector 1,50 €
1 SAM-euro-connector 2,50 €
a piece of board 2,50 €
some wiring and tin. 0,50 €
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Total 11,00 €
This is not boxed, or it will be a cigarbox since I do not have an alternative for a cigarbox.
VERY IMPORTANT NOTE: I will not have much time to built them!
