Ps/2 Keyboard Interface; Rams - XESS XStend Manual

Listing 6: Connections between the XStend VGA interface and the XS95.
# VGA CONNECTIONS
NET VSYNC_
NET HSYNC_
NET RED1
NET RED0
NET GREEN1
NET GREEN0
NET BLUE1
NET BLUE0

2.5 PS/2 Keyboard Interface

The XStend Board provides the 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.
Here are the connections from the XS40 and XS95 Boards to the PS/2 interface of the XStend
Board (expressed as UCF constraints):
Listing 7: Connections between the XStend PS/2 interface and the XS40.
# PS/2 KEYBOARD CONNECTIONS
NET KB_DATA
NET KB_CLK
Listing 8: Connections between the XStend PS/2 interface and the XS95.
# PS/2 KEYBOARD CONNECTIONS
NET KB_DATA
NET KB_CLK

2.6 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.
The XStend RAMs are disabled by removing the shunts on the following jumpers:
LOC=P24;
LOC=P15;
LOC=P14;
LOC=P18;
LOC=P17;
LOC=P19;
LOC=P23;
LOC=P21;
LOC=P69;
LOC=P68;
LOC=P70;
LOC=P26;