I am into retro-computing and one of my treasures is an SB180FX microcomputer: an HD64180 CPU running at blazing 9.something MHz and having a whopping 512kB RAM!

The "machine" has an NCR5380 SCSI host-adapter and a 9266 FDC which supports up to 4 floppy drives.

I managed to start the original hard disk (all 40MB of it!!!!!) once to extract an image which I then transferred to a SCSI disk emulator which uses a micro-SD-card for storage (the smallest one I got was 8 GB, more than 50 times as big as the original HDD). The floppy drives are actually used only for booting and then switching to the HDD. Before they, too, stop working, I'd like to build something like an FDD emulator. Some FDD emulators exist which emulate a drive, I have been thinking about emulating the FDC AND the drives using an Atmel microcontroller and some glue-logic. For the latter, I'd like to use an FPGA (https://www.elektor.de/tinyfpga-bx).

So I will need to get into programming this to provide to the CPU a set of registers (a status register and two data registers, one for writing and one for reading) and some logic to do DMA. The main work will be done by an ATMega168 (or 328) which also uses an SD card for storage, being able to switch between virtual floppy disks on the SD card.

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This project is part of:

Hack Week 19


  • over 4 years ago: fos liked this project.
  • over 4 years ago: jmoellers originated this project.

  • Comments

    • bmwiedemann
      over 4 years ago by bmwiedemann | Reply

      Seems there are nice docs out there. Wouldnt it also be possible to use a softcore in the FPGA instead of an extra chip outside? Might make the FPGA more expensive, though.

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