Monster Floppy Disk Controller (Monster FDC)
ISA floppy disk controller card that supports up to 8 floppy drives
Introduction
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
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 type | Reference | Description | Quantity | Possible sources and notes |
|---|---|---|---|---|
| PCB | Monster PCB - Version 1.0 | 1 | Buy 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 Circuit | U1, U2 | Intel 82077AA FDC, 68 pin PLCC | 2 | eBay; Possible replacements: National Semiconductor PC8477BV-1 or PC8477AV-1, Intel 82077SL, Intel 82077AA with various suffixes |
| Integrated Circuit | U3 | 16C550 UART, 44 pin PLCC | 1 | Mouser 701-ST16C550CJ44-F |
| Integrated Circuit | U4 | GD75232N RS-232 Transceivers, 20 pin DIP | 1 | Mouser 595-GD75232N |
| Integrated Circuit | U5 | SST39SF010A - 128 KiB Flash ROM, 32 pin DIP | 1* | 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 U5 |
| Integrated Circuit | U6 | 28C256 32 KiB or 28C64 8 KiB EEPROM, 28 pin DIP | 1* | Mouser 556-AT28C25615PU, 556-AT28C64B15PU. Note: Install either U5 or U6. It is recommended to install U5 |
| Integrated Circuit | U7 | CD74HCT688E Magnitude Comparator, 20 pin DIP | 1 | Mouser 595-CD74HCT688E |
| Integrated Circuit | U8 - U10 | SN74AHCT138N 3-to-8 Decoder, 16 pin DIP | 3 | Mouser 595-SN74AHCT138N |
| Crystal Oscillator | X1 | 24 MHz, 4 pin DIP, Half Can | 1 | Mouser 520-TCH2400 |
| Crystal Oscillator | X2 | 1.8432 MHz, 4 pin DIP, Half Can | 1 | Mouser 520-TCH184-X |
| Connector | J1 - J4 | 2x17 pin shrouded header, 2.54 mm pitch, vertical | 4 | Mouser 517-30334-6002 |
| Connector | J5 | DE-9 D-Sub connector, male, right angle | 1 | Mouser 806-K22X-E9P-N-99 |
| Pin Header | JP1 - JP3 | 2x6 pin header, 2.54 mm pitch, vertical | 3 | Mouser 649-67996-112HLF |
| Pin Header | JP4 | 1x5 pin header, 2.54 mm pitch, vertical | 1 | Mouser 649-68000-205HLF |
| Pin Header | JP5 | 2x7 pin header, 2.54 mm pitch, vertical | 1 | Mouser 649-67996-114HLF |
| Pin Header | JP6 - JP9 | 2x2 pin header, 2.54 mm pitch, vertical | 2* | Mouser 649-67996-104HLF. Note: Do not install unless using PS/2 floppy drives that are powered by pin 3 |
| Capacitor | C1, C2 | 4.7 nF, 50V, MLCC, 5 mm pitch | 2* | Mouser 810-FG28X7R1H472KNT0. Note: Optional, only required when using Intel 82077AA FDC |
| Capacitor | C3 - C17 | 100 nF, 50V, MLCC, 5 mm pitch | 15 | Mouser 810-FG28X7R1H104KNT6 |
| Capacitor | C18 - C23 | 10 uF, 63V, Organic Polymer, 6.3 mm diameter, 2.5 mm pitch | 5 | Mouser 80-A759EA106M1JAAE60 |
| Resistor Array | RN1, RN2 | 1 kohm, bussed, 6 pin SIP | 2 | Mouser 652-4606X-1LF-1K |
| Resistor Array | RN3, RN4 | 10 kohm, bussed, 6 pin SIP | 2 | Mouser 652-4606X-1LF-10K |
| IC Socket | U1, U2 | 68 pin PLCC, through hole | 2 | Mouser 517-8468-11B1-RK-TP |
| IC Socket | U3 | 44 pin PLCC, through hole | 1 | Mouser 517-8444-11B1-RK-TP |
| IC Socket | U4, U7 | 20 pin DIP | 2 | Mouser 649-DILB20P-223TLF |
| IC Socket | U5 | 32 pin DIP | 1* | Mouser 649-DILB32P223TLF. Note: Install either U5 or U6. It is recommended to install U5 |
| IC Socket | U6 | 28 pin DIP | 1* | Mouser 649-DILB28P223TLF. Note: Install either U5 or U6. It is recommended to install U5 |
| IC Socket | U8 - U10 | 16 pin DIP | 1 | Mouser 649-DILB16P-223TLF |
| Oscillator Socket | X1, X2 | 4 pin DIP, Half Can | 2 | Mouser 535-1108800 |
| Jumper | JP1 - JP5 | Shunt, 2 pin 2.54 mm pitch | 13 | Mouser 806-SX1100-B |
| Computer Bracket | Keystone Electronics 9200-1 Bracket with DE-9 cut-out | 1 | Mouser 534-9200-1, or a 3D printed bracket. Note: Use when serial port components are populated | |
| Screw | 4-40 Hex screw for D-Sub Connector | 2 | Mouser 806-JSX-1000. Note: Use when serial port components are populated | |
| Computer Bracket | Keystone Electronics 9202 ISA Bracket | 1 | Mouser 534-9202. Note: Use when serial port components are not populated | |
| Screw | 4-40 / 1/4" screw (for attaching ISA Bracket to the board) | 2 | Mouser 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/Functionality | Components |
|---|---|
| Primary FDC Controller | U1, U8, U9, X1, J1, J2, JP1, JP6, JP7, C1*, C3, C5, C11, C12, C14, C19, RN1, RN4 |
| Secondary FDC Controller | U2, U8, U10, X1, J3, J4, JP1, JP2, JP3, JP8, JP9, C2*, C4, C6, C11, C13, C14, C20, RN2, RN4 |
| Serial port / UART | U3, U4, U8, U9, X2, J5, JP1, JP2, JP4, C7, C8, C11, C12, C15, C16, C17, C22, C23, RN4 |
| BIOS extension ROM | U5, U6, U7, JP5, RN3, C9, C10 |
| Shared components | C18 |
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.
