Difference between revisions of "Keyboard"

Latest revision as of 13:00, 3 November 2024

Number	$**FE
Decimal	254
Short desc.	Series of specific ports that read keyboard key presses.
Bit Mask	%xxxx xxxx ---- ---0 where only one bit in x is 0
Readable	Yes
Writable	No
Subsystem	Input

 bit 6 = EAR in from the tape audio jack
 bits 4:0 = key column result from keyboard, active low

nextreg 0x08 bit 0 can be set to select issue 2 keyboard which will affect reads of bit 6

Reads keys on the keyboard depending on the upper byte of the port number. The five keys are represented by bits 0-4 of the read byte, listed below with bit 4 first down to bit 0. A zero means that the key is pressed.

The top eight bits of the port address are active low signals that select one or more key rows for reading.

Port upper byte	Keys affected (row of keys)
$7F (bit 7)	B, N, M, Symbol Shift, Space
$BF (bit 6)	H, J, K, L, Enter
$DF (bit 5)	Y, U, I, O P
$EF (bit 4)	6, 7, 8, 9, 0
$F7 (bit 3)	5, 4, 3, 2, 1
$FB (bit 2)	T, R, E, W, Q
$FD (bit 1)	G, F, D, S, A
$FE (bit 0)	V, C, X, Z, Caps Shift

File:Speckeys.png

Wireless Keyboards

Most ps/2 keyboards commonly seen today are wired. Two models of wireless keyboard known to work well with the Next are the Microsoft Wireless Elite Keyboard 1011 and the Logitech Cordless Desktop Keyboard EX110.

@@ Line 8: / Line 8: @@
 |Subsystem=Input
 }}
+  bit 6 = EAR in from the tape audio jack
+  bits 4:0 = key column result from keyboard, active low
+* nextreg 0x08 bit 0 can be set to select issue 2 keyboard which will affect reads of bit 6
 Reads keys on the keyboard depending on the upper byte of the port number. The five keys are represented by bits 0-4 of the read byte, listed below with bit 4 first down to bit 0. A zero means that the key is pressed.