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Original PCB design by Sergey Kiselev.

Specifications

Floppy disk controller based on Intel 82077AA or National Semiconductor PC8477 FDC IC.
- Supports IBM PC, AT, and PS/2 floppy types from 160 KB 5.25" single side disks to 2.88 MB 3.5" ED (Extended Density) disks.
- Supports 2.88 MB IBM PS/2 drives (e.g. IBM FRU 64F4148 and IBM FRU 64F0204), that require +5V on pin 3. This feature is enabled using jumper JP1.
Serial port.
- Uses UART IC in PLCC package, supports newer UART versions such as 16C650 and 16C750 with extended FIFO.
- Also compatible with 16550 and 16450 ICs in PLCC package.
- UART I/O address and interrupt is selectable using a DIP switch. Supported I/O addresses: 3F8h, 2F8h, 3E8h, 2E8h. Supported interrupts: IRQ3, IRQ4, IRQ5, IRQ7.
8 KiB BIOS extension ROM.
- Supports 28C64 EEPROMs and 27C64 UV erasable EPROMs.
- The ROM is configured using a DIP switch: It can be enabled or disabled; the /WR line can be disabled; the address can be selected from 0C0000h to 0EE000h in 8 KiB increments.
All functions above are optional (can be either installed or not)

SW1.1 - SW1.4 - Serial port IRQ selection
- SW1.1: ON - IRQ3 (default setting for COM2 and COM4)
- SW1.2: ON - IRQ4 (default setting for COM1 and COM3)
- SW1.3: ON - IRQ5
- SW1.4: ON - IRQ7

Note: Only one of SW1.1 - SW1.4 should be ON. All switches can be off if software doesn't use interrupt based I/O.

SW1.5 - SW1.8 - Serial port base address selection
- SW1.5: ON - 0x2E8 (COM4)
- SW1.6: ON - 0x3E8 (COM3)
- SW1.7: ON - 0x2F8 (COM2)
- SW1.8: ON - 0x3F8 (COM1)

Note: One and only one of SW1.5 - SW1.8 switches should be ON.

SW2.1 - SW2.7 - ROM Configuration
- SW2.1: ON - Enable ROM; OFF - Disable ROM
- SW2.2: ON - Enable EEPROM write. This jumper is only relevant for EEPROM. It should be OFF if EPROM is used.
- SW2.3 - SW2.7 - ROM address. Refer to the table below
SW2.8 - Unused

SW2.3	SW2.4	SW2.5	SW2.6	SW2.7	Start Address	End Address	SW2.3	SW2.4	SW2.5	SW2.6	SW2.7	Start Address	End Address
ON	ON	ON	ON	ON	0xC0000*	0xC1FFF	OFF	ON	ON	ON	ON	0xE0000**	0xE1FFF
ON	ON	ON	ON	OFF	0xC2000*	0xC3FFF	OFF	ON	ON	ON	OFF	0xE2000**	0xE3FFF
ON	ON	ON	OFF	ON	0xC4000*	0xC5FFF	OFF	ON	ON	OFF	ON	0xE4000**	0xE5FFF
ON	ON	ON	OFF	OFF	0xC6000*	0xC7FFF	OFF	ON	ON	OFF	OFF	0xE6000**	0xE7FFF
ON	ON	OFF	ON	ON	0xC8000	0xC9FFF	OFF	ON	OFF	ON	ON	0xE8000**	0xE9FFF
ON	ON	OFF	ON	OFF	0xCA000	0xCBFFF	OFF	ON	OFF	ON	OFF	0xEA000**	0xEBFFF
ON	ON	OFF	OFF	ON	0xCC000	0xCDFFF	OFF	ON	OFF	OFF	ON	0xEC000**	0xEDFFF
ON	ON	OFF	OFF	OFF	0xCE000	0xCFFFF	OFF	ON	OFF	OFF	OFF	0xEE000**	0xEFFFF
ON	OFF	ON	ON	ON	0xD0000	0xD1FFF	OFF	OFF	ON	ON	ON	0xF0000***	0xF1FFF
ON	OFF	ON	ON	OFF	0xD2000	0xD3FFF	OFF	OFF	ON	ON	OFF	0xF2000***	0xF3FFF
ON	OFF	ON	OFF	ON	0xD4000	0xD5FFF	OFF	OFF	ON	OFF	ON	0xF4000***	0xF5FFF
ON	OFF	ON	OFF	OFF	0xD6000	0xD7FFF	OFF	OFF	ON	OFF	OFF	0xF6000***	0xF7FFF
ON	OFF	OFF	ON	ON	0xD8000	0xD9FFF	OFF	OFF	OFF	ON	ON	0xF8000***	0xF9FFF
ON	OFF	OFF	ON	OFF	0xDA000	0xDBFFF	OFF	OFF	OFF	ON	OFF	0xFA000***	0xFBFFF
ON	OFF	OFF	OFF	ON	0xDC000	0xDDFFF	OFF	OFF	OFF	OFF	ON	0xFC000***	0xFDFFF
ON	OFF	OFF	OFF	OFF	0xDE000	0xDFFFF	OFF	OFF	OFF	OFF	OFF	0xFE000***	0xFFFFF

Notes:

* - Address range conflicts with EGA / VGA BIOS.
** - 0xE0000 - 0xEFFFF address range is not available on IBM AT - Reserved for on-board BIOS extension ROMs
*** - 0xF0000 - 0xFFFFF address range is not available on IBM PC, IBM XT, and IBM AT - Used system BIOS or reserved for on-board BIOS extension ROMs

When setting ROM address make sure it doesn't conflict with system BIOS and with BIOS extension ROMs of other cards installed in the system.

Some component manufacturers may differ from those shown in the picture, but this does not affect the functionality of the device.

Documentation is available on

https://github.com/skiselev/isa-fdc