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A Floppy Disk Controller (FDC) is a special-purpose chip and associated circuitry that directs and controls reading from and writing to a computer's floppy disk drive. Jump to: navigation, search A computer is a device or machine for processing information from data according to a program — a compiled list of instructions. ...
Jump to: navigation, search A floppy disk is a data storage device that is composed of a circular piece of thin, flexible (i. ...
Overview
A single FDC board can support upto four Floppy disk drives. The FDC is linked to the system bus of the computer and appears as a set of I/O ports to the CPU. It is also connected to a channel of the DMA controller. The FDC interrupts the CPU at level 6. The FDC usually performs data transmission in DMA mode. A floppy disk is a data storage device that comprises a circular piece of thin, flexible (hence floppy) magnetic storage medium encased in a square or rectangular plastic wallet. ...
Jump to: navigation, search A computer is a device or machine for processing information from data according to a program — a compiled list of instructions. ...
This article is about the computer interface. ...
Jump to: navigation, search This article needs to be cleaned up to conform to a higher standard of quality. ...
Jump to: navigation, search Direct memory access (DMA) allows certain hardware subsystems within a computer to access system memory for reading and/or writing independently of the CPU. Many hardware systems use DMA including disk drive controllers, graphics cards, network cards, and sound cards. ...
In computer engineering, an interrupt is a signal from a device which typically results in a context switch: that is, the processor sets aside what its doing and does something else. ...
 Block diagram showing FDC communication with the CPU and the FDD. Most of the FDC functions are performed by the FDC IC but some are performed by external hardware circuits. The list of functions performed by each is given below. Jump to: navigation, search Image File history File links Fdcinpc. ...
FDC IC Functions - Generating MFM format for the data to be recorded
- Decoding and executing commands such as seek, read, format etc
- Error detection by CRCC generation / checking
- Data synchronisation
External Hawrdware functions - Selection of FDD
- Switching-on motor in the FDD
- Resetting the FDC IC
- Enabling / disabling interrupt and DMA signals of the FDC IC
- Data seperation logic
- Write pre-compensation logic
- Line drivers for signals to the FDD
- Line receivers for signals from the FDD
This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ...
Input / Output ports The FDC has three I/O ports. These are: This article is about the computer interface. ...
- Data port
- Main status register (MSR)
- Control port
The first two reside inside the FDC IC while the Control port is in the external hardware. The addresses of these three ports are as follows. Hardware is equipment such as fasteners, keys, locks, hinges, latches, corners, handles, wire, chains, plumbing supplies, tools, utensils, cutlery and machine parts, especially when they are made of metal. ...
| Port Address | Port Name | Location | Port Type | | 3F5 | Data Register | FDC IC | Bidirectional I/O | | 3F4 | Main Status Register | FDC IC | Input | | 3F2 | Digital Control Port | External Hardware | Output |
Data Port This port is used by the software for three different purposes: - While issuing a command to the FDC IC, command and command parameter bytes are issued to the FDC IC through this port. The FDC IC stores the different parameters and the command in its internal registers.
- After a command is executed, the FDC IC stores a set of status parameters in the internal registers. These are read by the CPU through this port. The different status bytes are presented by the FDC IC in a specific sequence.
- In the programmed and interrupt mode of data transfer, the data port is used for transferring data between the FDC IC and the CPU IN or OUT instruction.
Main Status Register (MSR) This port is used by the software to read the overall status information regarding the FDC IC and the FDD's. Before initiating a floppy disk operation the software reads this port to confirm the readiness condition of the FDC and the disk drives to verify the status of the previously initiated command. The different bits of this register represent : Computer software (or simply software) refers to one or more computer programs and data held in the storage of a computer for some purpose. ...
| Bit | Representation | | 0 | FDD 0 : Busy in seek mode | | 1 | FDD 1 : Busy in seek mode | | 2 | FDD 2 : Busy in seek mode | | 3 | FDD 3 : Busy in seek mode | | 4 | FDC Busy; Read/Write command in progress | | 5 | Non-DMA mode | | 6 | DIO; Indicates the direction of data transfer between the FDC IC and the CPU | | 7 | RQM; Indicates data register is ready for data transfer |
Digital Control Port This port is used by the software to control certain FDD and FDC IC functions. The bit assignments of this port are: | Bit | Representation | | 0 and 1 | Device number to be selected | | 2 | RESET FDC IC (Low) | | 3 | Enable FDC interrupt and DMA request signals | | 4 to 7 | Turn ON the motor in disk drive 0, 1, 2 or 3 respectively | |
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