Hi,

> I have built a software Bell 201 (FSK) modem modulator using the 16C57 and a
> demodulator with the 16C71 (for the A/D).  The modulator would fit in a '54
 but
> I needed the '57 RAM for the rest of the application.  My application is
> half-duplex HDLC and I have to do the HDLC CRC as well as another software
 UART.
>  I think I could get full duplex in the '71 if I didn't have to do the
 software
> UART concurrently.

Impressive.

> Does anyone have experience with clocking the 16C84 faster than 10MHz?  I know
> the EPROM parts will typically got 30 or even 40 MHz although I wouldn't try
 it
> in production.

I was looking at using some 16C62 or similar parts for an application
but due to no immediate stock I did the testing with C84 parts.

I wanted to run at 20 MHz but found that the C84 worked at 16 MHz
and sometimes (same IC even) at 18 MHz and never at 20 MHz all
this was done with an external ocillator can in HS mode.

I expect the Microchip people hoped to get the speed to 20 MHz but
the technology of the day could not do it reliably.  Perhaps they
will come out with another EEPROM data memory device one of these
days with OTP code memory and 1 kByte of EEPROM data.  Never had any
luck with getting prices on the dual chip uP plus serial EEPROM
devices.  Though I notice they have some new ones with a 16C58
core and 1 kB memory.

Cheers
--
Kalle Pihlajasaari     kalle@data.co.za
Interface Products     Box 15775, Doornfontein, 2028, South Africa
+27 (11) 402-7750      Fax: +27 (11) 402-7751