Re: Hardware Guru for Hire?

Barry Watzman wrote:

I was not as clear as I should have been in my previous post.

A standard NEC 765 can do the 4 sector sizes that have been widely used (128, 256, 512, 1024 bytes). But the USB-to-FDC chip in question doesn't, taken as a whole, necessarily support everything that the 765 could do. PCs have only used the 512 byte sector size. The USB-to-FDC chip is a whole microprocessor PLUS an FDC chip WITH A FIRMWARE OPERATING SYSTEM. Even if the hardware component of this chip can do all 4 sizes (likely, but not an absolute given),

The data *** indicates that it is the standard SMSC floppy controller,
and I found a data *** with a detailed description of that controller.
It seems to do 128, 256, 512, ..., 16384 sector sizes.

the firmware in the stock chip might only do 512 bytes. There may be versions of this chip that support external firmware,

It does say how to use external firmware, by tying ROMEN low.

When internal firmware is used, a serial EEPROM supplies the USB
configuration data.

and on a volume basis, custom firmware can be implemented and ordered. But if the discussion relates to the most common mask firmware stock version(s) of the chip, it may not be possible to implement sector sizes other than 512 bytes. I'm not saying absolutely that it isn't, I'm saying it's an area for concern/investigation.

The processors is an 8051, so the documentation should be easy
to find. I don't see that source code is available, but it might
be that it is. (with comments).

Also, in the context of my response that certain things might not be "programmable", I was defining "programmable" as "programmable from the PC via the USB connection", and I was referring to the "stock" version of the chip, not a version with custom external firmware.

There is a pin to select external firmware, and pins to address
the external ROM. They don't seem to be optional.

There is no doubt that what we want can be done (with this part or other parts), but there is very great doubt that it can be done with the stock, standard version of this chip and it's stock, standard internal firmware.

That is true.

-- glen

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