[Opendispense] beginnings of code

Bernard Blackham bernard@blackham.com.au
Tue Aug 5 15:27:47 2003

I think I've gone a little insane pulling apart HC11 assembly so I
decided to start pulling some C code together. From what can be
ascertained from the disassembly, we can drive the display, chime,
motors and keypad (though the motors & chime could do with some more

What's really left to figure is the coin mech, but I've had enough
of the disassembly for now. The coin mech is not a "Changer", nor is
it a "Dumb Mech" (as per the options in the manual or on the vending
machine). The manual only ever refers to it as a "European Dumb Coin
Mechanism" and it is infact enabled by selecting "Link Master", and
hence the code I was previously looking at was useless to us.
Strangely enough, it also claims that this is incompatible with the
other credit items (eg bill acceptors, card readers), but I want to
say this is partially a software limitation.

Though what does seem interesting is the fact that it seems the
serial line appears to be in some ways, like a bus (certain parts of
the SCI interrupt code only respond to certain bit patterns in the
first byte of a packet) - and with the spare connector hanging out
of the coin mechanism, it's one potential way to get real-world
interfacing going without hacking the main board.

The alternative, is the Bill Acceptor connector P4 - curious why we
needed one, I unplugged P4 today and the machine ran perfectly fine
without it. So we could possibly hook something up to that.

Meanwhile, if anybody wants to checkout cvs directory ROM2 and
comment on the little C code that's gone in so far, please do :)

Furthermore, if anybody could shed some light on how this is going
to link to a 32KB ROM image with code, data, interrupt vectors et al
in the right place, I'd be even more thrilled =)



 Bernard Blackham 
 bernard at blackham dot com dot au