Kejora Our list has the most common: Many mutually incompatible floppy disk formats are possible; aside from the physical format on the disk, incompatible file systems are also possible. While we will take a brief look at all 40 pins, we will not look at it in full detail here as that is when we cross into the electronics field. The addresses of these three ports are as follows. A command byte only uses the low 4 bits of the byte for the actual floopy can be more. During this time, you must reinitialize the controller and drive configuation.
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After the Write Data command has been issued the FDC loads the head if it is in the unloaded state , waits the specified head settling time defined in the Specify Command , and begins reading ID Fields. After writing data into the current sector, the Sector Number stored in "R" is incremented by one, and the next data field is written into.
If a Terminal Count Signal is sent to the FDC it continues writing into the current sector to complete the data field. If the Terminal Count signal is received while a data field is being written then the remainder of the data field is filled with 00 zeros.
Status Register 0 also has bits 7 and 6 set to 0 and 1 respectively. The Write Command operates in much the same manner as the Read Command. It will read all the data in the sector and set the CM flag in Status Register 2 to a 1 high , and then terminate the command.
Multi-track or skip operations are not allowed with this command. This command terminates when EOT number of sectors have been read.
Status Register 0 has bits 7 and 6 set to 0 and 1 respectively. The Data Field is filled with the byte of data stored in D. This allows the diskette to be formatted with non-sequential sector numbers, if desired.
After formatting each sector, the processor must send new values for C,H,R and N to the for each sector on the track. Also the loss of the READY signal at the beginning of a command execution phase causes command termination.
FLOPPY DISK CONTROLLER 8272 PDF