ddi-1 can read single density????

[arnoldemu]

Looking at the schematics for the ddi-1 I can see that the MFM pin of the NEC765 is connected to the data seperator??

But in 664 and 6128 this pin is forced (low) to force MFM only.

Am I understanding the schematics correctly?

[Targhan]

Never tried it, but each instruction of the FDC has a bit in order to read singe/double density. I always thought it could be possible to read/write single density tracks...

[Bryce]

Hi arnoldemu,
          I just took a look at the schematics and indeed, you seem to be correct. Perhaps this was to allow other external disk drives to be used with the interface? Future plans that never came? who knows? In the 6128 they possibly didn't offer this functionality for cost reasons, due to the fact that the drive wasn't designed to be replaced with any alternatives (the 6128 design seems to be a lower cost solution compared to the DDI-1), the 6128 uses an FDC9216, whereas the DDI-1 uses the FDC9229 with more functionality.

Well spotted.

Bryce.

[arnoldemu]

Hi arnoldemu,
          I just took a look at the schematics and indeed, you seem to be correct. Perhaps this was to allow other external disk drives to be used with the interface? Future plans that never came? who knows? In the 6128 they possibly didn't offer this functionality for cost reasons, due to the fact that the drive wasn't designed to be replaced with any alternatives (the 6128 design seems to be a lower cost solution compared to the DDI-1), the 6128 uses an FDC9216, whereas the DDI-1 uses the FDC9229 with more functionality.

Well spotted.

Bryce.

thankyou for looking.

It is good to know that I was correct.

[TFM]

In the floppy book (german) they wrote that MFM and FM can be used. But I never tried FM. If you want to know it exactly, just format a track in FM and write and read a sector. The rest is history ;-)