Re: Commodore drives can be controlled on Apple II serial!

[supertimer@aol.com (Supertimer)]

dempson@actrix.gen.nz (David Empson) wrote:

>Supertimer <supertimer@aol.com> wrote:
>
>>So, based on what David wrote about the SmartPort, can it be used to
>>emulate Commodore serial I/O?
>> 
>>I think that PH0 through PH3 must be the drive control lines that can
>>be controlled through software.  Pins 1 through 3 are ground.  Pins
>>18 and 19 look like the serial input and output.
>
>Pins 18 and 19 are the read and write data lines, which have the timing
>and data format restrictions (4 microseconds per bit cell, bit 7 must be
>set for reading, write must be every 32 microseconds exactly).
>
>The only signals that can be controlled directly by the CPU are PH0-PH3
>and the drive enable lines (only one enable line is active at a time).
>
>Write Request is timed by and tied to the write sequence.  Write Protect
>is the "sense" input.  It is used for write protect on a 5.25" drive, as
>a general input for an Apple 3.5 drive.  From memory, there are
>restrictions on when it can be sensed by software (based on the
>read/write mode).
>
>The SIDE1 signal you mention only applies to an Apple 3.5 drive, and is
>only provided by the IIgs and IIc+.

David, I am very interested in getting the A2 to work with the 1571
drive of the Commodore 128 because it can read and write MFM
MS-DOS disks.  There is also a high density CMD 3.5" floppy that
is being manufactured...