Programming Considerations; Symbol Descriptions - IBM 5150 Hardware Reference Manual

Programming Considerations
Table 13.
Symbol Descriptions
The following tables define the symbols used in the command summary
which follows.
SYMBOL
NAME
AO
Address Une 0
C Cylinder Number
0
Data
07-00 Data Bus
OTL Data length
EDT End of Track
GPl
Gap length
H
Head Address
HO Head
HlT Head load Time
HUT Head Unload Time
MF FM or MFM Mode
MT Multi-Track
N Number
NCN New Cylinder
Number
2-94
OESCRIPTION
AO controls selection of Main Status Register
(AO
=
0) or Data Register (AO
=
1).
Cstands for the current/selected Cylinder
(track) number of the medium.
o
stands for the data pattern which is going to
be written into a Sector.
8-bit Data Bus, where 07 stands for a most
significant bit, and DO stands for a least
significant bit.
When N is defined as 00, OTl stands for the
data length which users are going to read out
or write into the Sector.
EDT stands for the final Sector number on a
Cylinder.
GPl stands for the length of Gap 3 (spacing
between Sectors excluding VCD Sync. Field).
Hstands for head number 0 or 1, as specified
in 10 field.
HO stands for a selected head number 0 or 1.
(H
=
H 0 in all command words.)
H l T stands for the head load time in the F 0 0
(4 to 512 ms in 4 ms increments).
HUT stands for the head unload time after a
read or write operation has occurred
(0
to
480 ms in 32 ms increments.)
If M F is low, FM mode is selected, and if it is high,
MFM mode is selected only if MFM is implemented.
If MT is high, a multi-track operation is to
be performed. (A cylinder under both HOO
and H D 1 will be read or written.)
Nstands for the number of data bytes written
in a Sector.
NCN stands for a new Cylinder number, which
is going to be reached as a result of the Seek
operation. Desired position of Head.