Enterprise Forever
:UK => Hardware => Interface => Topic started by: OA128 on 2007.March.05. 14:22:40
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again me ;)
I found a "System Bus Bridge" for EP128. What is its use ?
Bye !
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again me ;)
I found a "System Bus Bridge" for EP128. What is its use ?
Bye !
It's a connecting module between the machine and extensions (EXDOS floppy disc controller, hardware Spectrum Emulator).
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Schametic of the Bridge. (http://ep.homeserver.hu/Hardware/PCB/Picture/BRIDGE.jpg)
This generate +5V power suply for the extension card, can work from the 9V output from the machine, or other external power supply.
And added 3 address select pins. This is for "plug and play" :-) The connected card can decode standalone I/O port and memory addresses by these pins. But we never see officialy released multi sockets bus extender unit. And only one official card released, the EXDOS. Only this card use this address decoding method.
In Hungary is exist a unofficial Bus Extender unit (http://ep.homeserver.hu/Galery/Bovitmenyek/Picture/BuszBovito~5.jpg), but this and other unofficial cards not use the original address decoding idea :-(
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Thanks for your answers !
"It's a connecting module between the machine and extensions (EXDOS floppy disc controller, hardware Spectrum Emulator)."
If this module is always necessary, why didn't they include it into the computer ?
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If this module is always necessary, why didn't they include it into the computer ?
Price of the machine was lower... :) (Sorry, i don't speak english. :oops: )
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If this module is always necessary, why didn't they include it into the computer ?
Good question :-)
But all unofficial EXDOS cards in Hungary come with direct connector to machine.
I think the original developers thinked about the following things:
-not overload the machine power supply and the internal power circuits
-the address decoding mechanism (this is very good idea, but unfortunately not released more official cards, and multi slots bus extender)