SA1000 adapter board usage

The SA1000 adapter board allows my MFM emulator/reader to be used with hard disks that use the SA1000 interface. See here if you are assembling a bare board or for links to design files

For reading disks attach the SA1000 board to the MFM board J3 and J4. All other connections are to adapter board. Attach the 20 pin cable from the drive to P2. Attach the 50 pin cable from the drive to either P8 or P9. Follow the normal instructions for using the MFM reading function.

For reading Shugart disks that require the clock signal on the 20 pin cable the board requires 5V. It may be supplied through either the 4 pin P4 connector or the 6 pin P3 connector. If you supply power through the P4 connector it is better to not supply 12V since you will be reverse powering the 24V to 12V DC/DC converter. I tested 12V on P4 for a short while and it did not seem to cause any problems but may.

Shugart drives spin at 3125 RPM which is what my code assumes for these drives. Quantum drives spin at 3000 RPM. When creating emulator files from Quantum drives with mfm_read or mfm_util you will need to specify --track_words 5425 or the value printed by the code if it generates a warning when generating the emulator file. For creating them with mfm_emu use --rpm 3000 if you desire emulating the RPM of a Quantum drive. For a SA1004 drive this will create an emulator file 

./mfm_emu --init --file sa1004.emu --heads 4 --cyl 256 --drive 1 --rpm 3125 --rate 8680000


Cables to drive not plugged in to show board setup for reading better.

For emulating disks attach the SA1000 adapter board to the edge connectors on the MFM board. Attach the cables from the controller to the edge connectors on the adapter board. Attach the power cable to the 6 pin connector P3. Connect a jumper cable between the adapter board P4 to the MFM board J5. You may also power the MFM board directly through J5 and not connect power to adapter P3 and jumper is not needed. Follow the normal emulator usage except if using --initialize also add --rate 8680000

Adapter connected for emulation. Needed power cable between P4 and J5 was not installed when picture taken.

Quantum Q20x0 drives have deteriorating rubber that prevents the heads from moving. I have successfully freed them to read the disk


Feel free to contact me, David Gesswein djg@pdp8online.com with any questions, comments on the web site, or if you have related equipment, documentation, software etc. you are willing to part with.  I am interested in anything PDP-8 related, computers, peripherals used with them, DEC or third party, or documentation. 

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