🚀 go-pugleaf

> I would appreciate if someone could point out the differences among the 
> following devices:
> 
> MC68HC11A0FN
> MC68HC11A0P

All 68HC11 features, this configuration is:

256 bytes static RAM
no EEPROM

MC68HC11A0FN:	 52 pin quad
MC68HC11A0P:	 48 pin DIP (only 4 A/D inputs)

> MC68HC11A1FN
> MC68HC11A1P

256 bytes static RAM
512 bytes EEPROM

MC68HC11A1FN:	 52 pin quad
MC68HC11A1P:	 48 pin DIP (only 4 A/D inputs)

> MC68HCP11A1FN
> MC68HCP11A1P
??

sounds like a mistake, I'm pretty sure the naming is:

	68HCx11pp

	where x is the chip type, and pp is the package:

	x	
	blank	basic 68HC11 with or without mask ROM
	7	OTPROM
	8	EEPROM

	pp
	P	DIP package
	FN	quad pakage

I don't have my 68HC11 family book here to be sure.

> MC68HC11E1FN

512 bytes of EEPROM
512 bytes of static RAM

> What is the maximum frequency crystal that can be used with these MCUs.

up to 2 Meg bus clock == 8 meg Xtal

> I recall some comments here that some devices in the 68HC11 series cannot 
> (or can with great difficulty) be programmed/run with only the internal 
> EEPROM. I would appreciate hearing more detailed comments along these 
> lines.

There has been a number of discussions  about the HC11's lack of
an  elegant  power down reset (or  something).  Motorola  has an
application note out about how to add stuff to detect low power,
and   reset.  Compared   to   the   HC05,   the   HC11's   whole
power_up_down/reset  stuff is a bit  lacking.  The  HC05  claims
(though I haven't  tried one yet - this  weekend :-) that it has
all the good stuff on chip, and is self  contained  with need of
just the crystal  and power to run.  The data books for the HC11
(and I'm not smart enough to deviate from what they say) suggest
a Motorola MC34064, or Seiko S8054HN low voltage inhibit circuit
to  properly  handle the low power  reset  situation.  These are
really  hard to find!  Does  Active  have them?  Again, the book
suggests an alternative circuit of 14(!)  parts.

> These devices are priced between $10.90 and $34.50. Can you recommend 
> other devices in this price range that sport async serial I/O and modest 
> onboard program EEPROM that are readily available?
> 
> The Active catalog also mentions the
> 
> MC68HC705C8FN
> MC68HC705C8P
> Are these really OTP EPROM devices, or are they windowed?

	MC68HC705C8FN:	44 pin quad OTPROM
	MC68HC705C8P:	40 pin DIP OTPROM
	MC68HC705C8S:	Ceramic 40 pin DIP (I think) EPROM

These guys, like the HC11s can program  themselves.  It's all in
the data book.

Hope that helps - I wondered why I brought my Motorola data book
to work today :-)

David Williams
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