By Sergei Kiselev

GITHUB: https://github.com/skiselev/monster-fdc

Monster FDC is an ISA floppy disk controller card that features two FDCs. Each FDC supports up to four floppy drives. IRQ and DMA channel are configurable for the secondary FDC, and they are hardwired to IRQ6 and DMA2 for the primary FDC. The card also includes a serial port (UART) with configurable I/O address and IRQ.

User Manuals

Refer to Assembly Instructions for the controller board building instructions

Refer to User Manual for configuration, installation, and using the controller board in the computer

Hardware Documentation

Schematic and PCB Layout

Schematic - Version 1.0

PCB Layout - Version 1.0

Bill of Materials

Version 1.0

Monster FDC project on Mouser.com - View and order all components except of the PCB and the FDC ICs. Note that this BOM includes multiple alternatives for some parts (for example, for 2x17 pin floppy disk connector). Make sure to refer to the BOM below to order the right number of components.

Monster FDC project on Tindie: Complete Board; Monster FDC PCB.

Component typeReferenceDescriptionQuantityPossible sources and notesPCBMonster PCB - Version 1.01Buy from my Tindie store: Monster FDC PCB, or order from a PCB manufacturer of your choice using provided Gerber or KiCad files. It is recommended to use hard gold plating on the card edge connector. ENIG finish might work, but it is not as reliable. Definitely DO NOT use HASL finish on card edge connector.Integrated CircuitU1, U2Intel 82077AA FDC, 68 pin PLCC2eBay; Possible replacements: National Semiconductor PC8477BV-1 or PC8477AV-1, Intel 82077SL, Intel 82077AA with various suffixesIntegrated CircuitU316C550 UART, 44 pin PLCC1Mouser 701-ST16C550CJ44-FIntegrated CircuitU4GD75232N RS-232 Transceivers, 20 pin DIP1Mouser 595-GD75232NIntegrated CircuitU5SST39SF010A - 128 KiB Flash ROM, 32 pin DIP1*Mouser 804-39SF010A7CPHE; Possible replacements: 128 KiB, 256 KiB, or 512 KiB 5V only Flash ROMs from other vendors. Note: Install either U5 or U6. It is recommended to install U5Integrated CircuitU628C256 32 KiB or 28C64 8 KiB EEPROM, 28 pin DIP1*Mouser 556-AT28C25615PU, 556-AT28C64B15PU. Note: Install either U5 or U6. It is recommended to install U5Integrated CircuitU7CD74HCT688E Magnitude Comparator, 20 pin DIP1Mouser 595-CD74HCT688EIntegrated CircuitU8 - U10SN74AHCT138N 3-to-8 Decoder, 16 pin DIP3Mouser 595-SN74AHCT138NCrystal OscillatorX124 MHz, 4 pin DIP, Half Can1Mouser 520-TCH2400Crystal OscillatorX21.8432 MHz, 4 pin DIP, Half Can1Mouser 520-TCH184-XConnectorJ1 - J42x17 pin shrouded header, 2.54 mm pitch, vertical4Mouser 517-30334-6002ConnectorJ5DE-9 D-Sub connector, male, right angle1Mouser 806-K22X-E9P-N-99Pin HeaderJP1 - JP32x6 pin header, 2.54 mm pitch, vertical3Mouser 649-67996-112HLFPin HeaderJP42x7 pin header, 2.54 mm pitch, vertical1Mouser 649-67996-114HLFPin HeaderJP51x5 pin header, 2.54 mm pitch, vertical1Mouser 649-68000-205HLFPin HeaderJP6 - JP92x2 pin header, 2.54 mm pitch, vertical2*Mouser 649-67996-104HLF. Note: Do not install unless using PS/2 floppy drives that are powered by pin 3CapacitorC1, C24.7 nF, 50V, MLCC, 5 mm pitch2*Mouser 810-FG28X7R1H472KNT0. Note: Optional, only required when using Intel 82077AA FDCCapacitorC3 - C17100 nF, 50V, MLCC, 5 mm pitch15Mouser 810-FG28X7R1H104KNT6CapacitorC18 - C2310 uF, 63V, Organic Polymer, 6.3 mm diameter, 2.5 mm pitch5Mouser 80-A759EA106M1JAAE60Resistor ArrayRN1, RN21 kohm, bussed, 6 pin SIP2Mouser 652-4606X-1LF-1KResistor ArrayRN3, RN410 kohm, bussed, 6 pin SIP2Mouser 652-4606X-1LF-10KIC SocketU1, U268 pin PLCC, through hole2Mouser 517-8468-11B1-RK-TPIC SocketU344 pin PLCC, through hole1Mouser 517-8444-11B1-RK-TPIC SocketU4, U720 pin DIP2Mouser 649-DILB20P-223TLFIC SocketU532 pin DIP1*Mouser 649-DILB32P223TLF. Note: Install either U5 or U6. It is recommended to install U5IC SocketU628 pin DIP1*Mouser 649-DILB28P223TLF. Note: Install either U5 or U6. It is recommended to install U5IC SocketU8 - U1016 pin DIP1Mouser 649-DILB16P-223TLFOscillator SocketX1, X24 pin DIP, Half Can2Mouser 535-1108800JumperJP1 - JP5Shunt, 2 pin 2.54 mm pitch13Mouser 806-SX1100-BComputer BracketKeystone Electronics 9200-1 Bracket with DE-9 cut-out1Mouser 534-9200-1. Note: Use when serial port components are populatedScrew4-40 Hex screw for D-Sub Connector2Mouser 806-JSX-1000. Note: Use when serial port components are populatedComputer BracketKeystone Electronics 9202 ISA Bracket1Mouser 534-9202. Note: Use when serial port components are not populatedScrew4-40 / 1/4" screw (for attaching ISA Bracket to the board)2Mouser 534-9900. Note: Use when serial port components are not populated

Devices and Functionality

The card can be built with some or all of the following devices and functionality:

Primary FDC controller

Secondary FDC controller

Serial port / UART

BIOS extension ROM (aka boot ROM)

The table below provides the list of components that are required for each one of the devices

Device/FunctionalityComponentsPrimary FDC ControllerU1, U8, U9, X1, J1, J2, JP1, JP6**, JP7**, C1*, C3, C5, C11, C12, C14, C19, RN1, RN4Secondary FDC ControllerU2, U8, U10, X1, J3, J4, JP1, JP2, JP3, JP8**, JP9**, C2*, C4, C6, C11, C13, C14, C20, RN2, RN4Serial port / UARTU3, U4, U8, U9, X2, J5, JP1, JP2, JP4, C7, C8, C11, C12, C15, C16, C17, C22, C23, RN4BIOS extension ROMU5***, U6***, U7, JP5, RN3, C9, C10Shared componentsC18

Notes:

* - only required for Intel 82077AA FDCs

** - only required when using IBM PS/2 floppy drives that are powered by 5V on pin 3

*** - install either U5 (recommended) or U6

Use Keystone Electronics 9200-1 Bracket when populating serial port components. This bracket attaches to the serial port DE-9 connector

Use Keystone Electronics 9202 ISA Bracket when not populating serial port components. This bracket attaches to the board with a couple of 4-40 screws

Possible Component Replacements

U1, U2 - Intel 82077AA FDC

National Semiconductor PC8477BV-1 - recommended

Intel N82077SL - recommended

Intel N82077AA - recommended, no tape support

Intel N82077AA-1 - tape support, FM broken

Intel N82077AA-5 - doesn't support 1 Mbps rate / ED disks

National Semiconductor PC8477AV-1 - an older version of PC8277BV-1

U3 - 16C550 UART

Most 16450/16550A type UARTs in PLCC-44 package supporting 5V operation

16C550 and 16550A type UARTs from other vendors - Texas Instruments, National Semiconductor, MaxLinear, NXP Semiconductors

16C650, 16C750, 16C850 type UARTs (longer FIFO)

16C450, 16450, 16550 type UARTs without FIFO

U4 - GD75232N RS-232 Transceivers

Texas Instruments SN75185N, SN75C185

U5 - 128 KiB Flash ROM

Most 128 KiB Flash ROM ICs in DIP-32 package supporting 5V-only operation

Microchip/SST SST39SF010A, SST39SF020, SST39SF040

AMD Am29F010, Am29F020

Winbond W29EE011

Atmel AT29C010A

Greenliant/SST SST29EE010/GLS29EE010

256 KiB, and 512 KiB Flash ROM ICs in DIP-32 package supporting 5V-only operation can be used as well, but are not currently supported by the built-in configuration utility and xiflash utility

Note that only first 32 KiB will be used regardless of the ROM capacity

U6 - 32 KiB or 8 KiB EEPROM

Atmel AT28C256, AT28C64B

U7 - CD74HCT688E Magnitude Comparator

74HCT688

74LS668, 74F521

U8 - U10 - SN74AHCT138N 3-to-8 Decoder

74AHCT138

74HCT138

74ALS138, 74F138, 74LS138

X1

Any 24 MHz half can 5V oscillators

X2

Any 1.8432 MHz half can 5V oscillators

Release Notes

Changes

Version 1.0

Initial version

Known Issues

None, so far

Red Tape

Licensing

Monster FDC is an open source hardware project certified by Open Source Hardware Association, certification UID is US002072. The hardware design itself, including schematic and PCB layout design files are licensed under the strongly-reciprocal variant of CERN Open Hardware Licence version 2. The Multi-Flopppy BIOS code is licensed under GNU General Public License v3. Documentation, including this file, is licensed under the Creative Commons Attribution-ShareAlike 4.0 International License.