Obsoleteness of the HC11... (not quite)

Started by autostaretx July 24, 2006

Folks comment on how the m68hc11 family is obsolete and
shouldn't be used in new designs.

Not everyone follows that rule, however.

Meade ( www.meade.com ) makes a number of automated telescope
families using their "Autostar" embedded computer system.
The primary processor is an mc68hc11e1c1n2

It talks via a modified I2C bus to a bunch of distributed
PIC chips on subsidiary boards throughout the telescope
(one for each motor, plus others for various sensor duties).

The m68hc11 has either 1 MB (497 hand-held autostar, photos
at http://www.weasner.com/etx/autostar/as_schematic.html ),
3.5 MB (Autostar II in LX200gps scope) or 4 MB (RCX400) of
FlashRam to hold the program and celestial object databases.
The FlashRam is mapped to the upper half of the 64KB address
range, and it has 32KB of static ram as the lower half.
The on-chip device registers are mapped to start at 0000.

The LX200gps and RCX400 have the main board in the base of
the telescope, and the handbox is merely a keypad, screen and
beeper on an rs232 hookup. The 497 Autostar puts all of the
brains in the handbox, and the cable has three I2C bus pairs,
plus power and ground.

More details on "how they work" are covered in Meade's patents:
6,304,376 6,392,799 6,445,498 6,563,636 align: 6,922,283
readable at:

Since the 'firmware' is in FlashRam, Meade can issue updates
which users can upload to replace the existing program and data.
They do not provide program information or modification tools.

The original programming was produced by John Hoot of SSC Corp:
Prior to these models, Meade produced the "Classic" LX200, which
used a MC68000 as its core processor, without slave subprocessors.

As a hobby, i disassemble the Meade code (which appears to originally
have been written in C) and provide free 'patch kits' to the user
groups to fix bugs and add features Meade doesn't deem worthy
(or safe?).
My disassembly tools are home-made, and a long echo from when
i used to do the same thing to Radio Shack Color Computers
(mc6809) in the early '80s.

have fun