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

[Rubywand <rubywand@swbell.net>]

pubpc1@library.ucla.edu writes ...
> 
> dr.ido@usa.net wrote:
> >
> > While Commodore drives are serial, they are not RS-232.  Every adapter that I
> > have seen to run then from a PC uses the parallel port.  It may be possible to
> > run one from an RS-232 port, but it would take more than a cable.  Somethine
> > like a MAX232 would be needed to handle level conversion at the very least.
> > Then once you have an RS-232 interface you would have to get the IIe to
> > communicate with this interface at 3600bps (1571 burstmode uses a higher
> > rate, but I can't remember what it is).
> 
> You mean 36000bps, right?  I can't believe a disk drive can be
> just a little faster than a 2400bps modem!
>

     According to timing charts in the C64 manual, the Serial Clock
period is normally 40uS (for a frequency of 25kHz).  36kHz may be the
speed at which a newer model drive operates. In any case, we are talking
about really _slow_ disk I/O. Burst Mode would have to support much
faster transfer rates to come close to Disk ][ speed.  


 
> The IIGS serial ports are not restricted to RS-232.  In fact,
> they are another standard RS-4?? something or other.

     The Spectrum manual says that, with the hardware handshaking, the
GS serial port operates as an RS-423 connection.



>  The comm
> chip int he IIGS is very good at doing many different tasks.
> If a serial port can be programmed to do nonstandard things, it
> has to be the IIGS'. ....
>

     Yes; but, in this case the GS serial port does not have enough
outputs. Also, there seems to be no good way to synchronize the serial
port data output with a serial clock output. It looks like the interface
will have to come from the GS (II+, IIe, ...) 16-pin Game port.  



Rubywand