IBM 5150 Hardware Reference Manual page 122

Table 17.
Status Register 3
BIT
NO. NAME
SYMBOL DESCRIPTION
07
Fault FT
This bit is used to indicate the status of
the Fault signal from the FOO.
OS Write Protected WP
05 Ready
RY
04
Track 0
TO
03
Two Side TS
02
Head Address
HO
01 Unit Select 1
US 1
DO
Unit Select 0
US 0
Programming Summary
DPe Registers (Ports)
FDC Data Reg
FDe Main, Status Reg
Digital Output Reg
Bit 0 Drive
1
Select
2
Not FDC Reset
This bit is used to indicate the status of
the Write Protected signal from the FOD.
This bit is used to indicate the status of
I
the Ready signal from the FDD.
~
This bit is used to indicate the status of
f:
the Track 0 signal from the FOO.
~
This bit is used to indicate the status of
the Two Side signal from the FDD.
I
This bit is used to indicate the status of
Side Select signal to the FOD.
This bit is used to indicate the status of
the Unit Select 1 signal to the FOO.
This bit is used to indicate the status of
the Unit Select 0 signal to the FOD.
I/O Address 3F5
110 Address 3F4
I/O Address 3F2
OO:DR#A 10: DR #C
01: DR #B
11:
DR #D
3
Enable INT
&
DMA Requests
4
Drive A Motor Enable
5
Drive B Motor Enable
6 Drive C Motor Enable
.
7
Dnve D Motor Enable
All bits cleared with channel reset.
2-103