Chapter 2
Startup and Shutdown
2-2
KT
x
Status Register (byte :0804h)
Important: This is a read-only byte.
This byte reports the status of several properties of the KTx card.
This table describes what each bit contains.
Bit
Status Code Meaning
7
0 = Z80 is deasserted
1 = Z80 is asserted
6
0 = Z80 is in the halt state
1 = Z80 is not in the halt state
5
0
4
0
3
0
2
0
1
0
0
0 = no hardware interrupt is currently asserted
1 = a hardware interrupt is currently asserted
(stays active till host writes 0x1 to 808)
Host Interrupt Acknowledge (byte :0808h)
Write a 01h to this address to acknowledge an interrupt from the KTx.
This will reset bit 0 of the status register.
Card Control Write Register (byte :080Ah)
Important: This is a write-only register.
Bit
Status Code Meaning
7
unused
6
5
4
3
2
1
1 = puts the KT
x
into E/ISA 16bit mode; will not work
with 8bit devices in the same 128K block of memory
0 = extended 16bit mode; can mix 8 and 16bit devices;
0 is the default.
0
1 = E/ISAlevel interrupts
0 = edgetriggered interrupts; 0 is the default.