XESS XStend XS40, Manual

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10
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Listing 6: Connections between the XStend VGA interface and the XS95.
# VGA CONNECTIONS
NET VSYNCB LOC=P24;
NET HSYNCB LOC=P15;
NET RED<1> LOC=P14;
NET RED<0> LOC=P18;
NET GREEN<1> LOC=P17;
NET GREEN<0> LOC=P19;
NET BLUE<1> LOC=P23;
NET BLUE<0> LOC=P21;
PS/2 Keyboard Interface
The XStend Board provides an XS Board with a PS/2-style interface (mini-DIN connector
J6) to either a keyboard or a mouse. The XS Board receives two signals from the PS/2
interface: a clock signal and a serial data stream that is synchronized with the falling edges
on the clock signal.
Listing 7 and Listing 8 show the connections from the XS40 and XS95 Boards to the
PS/2 interface of the XStend Board (expressed as UCF constraints):
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Listing 7: Connections between the XStend PS/2 interface and the XS40.
# PS/2 KEYBOARD CONNECTIONS
NET KB_CLK LOC=P68;
NET KB_DATA LOC=P69;
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Listing 8: Connections between the XStend PS/2 interface and the XS95.
# PS/2 KEYBOARD CONNECTIONS
NET KB_CLK LOC=P26;
NET KB_DATA LOC=P70;
RAMs
The XStend Board adds an additional 64 KBytes of RAM to the 32 KBytes already on the
XS Board. The XStend RAM connects to the same pins as the XS Board RAM for the
address bus, data bus, write-enable, and output-enable. The chip-selects of the XStend
Board RAMs are connected to different pins so all the RAMs can be individually selected.
Listing 9 and Listing 10 show the connections from the XS40 and XS95 Boards to their
own RAMs and the RAMs of the XStend Board (expressed as UCF constraints):
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Listing 9: Connections between the XStend RAMs and the XS40.
NET D<0> LOC=P41; # DATA BUS
NET D<1> LOC=P40;
NET D<2> LOC=P39;
NET D<3> LOC=P38;
NET D<4> LOC=P35;
NET D<5> LOC=P81;