| Monster FDC - Dual-FDC floppy disk controller card supporting 8 floppy drives [message #9448] |
Fri, 03 December 2021 16:00  |
Sergey
Messages: 236
Registered: October 2015
Location: Portland, OR
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Senior Member |
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Hi,
A few people recently asked about connecting more than 2 drives to their PCs... So here is my answer - Monster FDC controller.
(Of course one could install a second FDC card, but what is the fun in this?! Also there are not many cards out there that can be configured as a secondary FDC)
The card is fairly flexible. It can have up to two Intel 82077 or National Semiconductor PC8477B. One is hardwired as a primary FDC - I/O base address 0x3F0, IRQ6, DMA channel 2), another is configured as a secondary FDC - I/O base address 0x370, IRQ and DMA are configurable. It appears that two FDCs can share an IRQ and DMA, by disabling IRQ/DMA using bit 3 of the FDC Digital Output Register (DOR) while the FDC is not active. Of course either one of FDCs is optional.
The card also includes a socket for the BIOS extension ROM that supports either 32-pin Flash ROM devices or 28-pin EEPROMs, and a serial port, which has configurable I/O base and IRQ.
The current design files are here: https://github.com/skiselev/monster-fdc
The design is mostly done, and I am interested to hear any feedback.
- Would you be interested in something like this?
- Should I offer fully assembled cards? a kit? PCBs only? All of the above?
Some intentional design choices:
- No external FDC connector - It is not difficult to make a 34 pin header to DC-37 connector cable using IDC connectors and a piece of a ribbon cable
- No card edge FDC connector - again, a matter of making cables. There are plenty of pin header style cables out there...
- Jumpers instead of switches.... they make IRQ selection more fun, and also more visible
Thanks,
Sergey
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