DEC VT220 Technical Manual page 212

CTUR ADDRESS
CTLR ADDRESS
07 06
87F6H (RD)/87F6H (WRI
87F7H (RDi/87F7H (WR)
05 04 03 02 01 00
IBAD7 HI ....
I-------------------....
(BADO HI
BIT VALUES
BIT 0-7
lEAST SIGNIFICANT BYTE OF COUNTER OR TIMER MODE
(CTlRI
MOST SIGNIFICANT BYTE OF COUNTER OR TIMER MODE
(CTURI
Figure C-11
2681 DUART: Counter Timer/Upper
(CTUR) and Lower (CTLR) Registers
IPR ADDRESS
07 06
87FDH (RD)
05 04 03 02 01 00
I
I
I
I
NOT
I
IP6 IPS
IP4
IP3 IP2
IPl
IPC
USED
j
I
IBAD7 HI .....
I-------------------....
IBADO HI
BIT VALUES
BIT
6 011
Bn
5
0/1
BIT 4
011
BIT 3 0;1
BIT 2 0/1
BIT 1
011
BIT 0
On
Figure C-12
INOT USEDI
CURRENT STATE OF IPS !DTR DSR!
CURRENT STATE OF IP4 ITBlKi
CURRENT STATE OF IP3 ITVBI
CURRENT STATE OF IP2 (SPD INDI
CURRENT STATE OF IPl IDSR)
CURRENT STATE OF IPC (CTSi
2681 DUART: Input Port
Register (IPR)
C-9