Hi there everyone...
For those lucky people out there who have two SAMs at home, I've got
something you might like -- a widget called the BusMaster.
Basically, it plugs in the back of both SAMs and allows one to control the
other.
Currently, it uses ports C0-C4, doing the following:
C0 -- IO Action
C1 -- Memory action
C2 -- Control port
C3 -- Address lsb
C4 -- Address msb
Control port bits:
0 -- BUS Request line to slave SAM
1 -- NMI line to slave SAM
2 -- RESET line to slave SAM.
The idea is that you set the bus request, the set up an address in the
address lsb and msb ports. The you read or write from the IO or memory port
(depending on whether you want the IO port or memory addressing on the slave
SAM), and bob's your uncle. It's effectively what they use in PDS systems.
I'll be using it to program the MultiROM (and it should speed things up a
fair bit!)
It uses 10 chips, namely a hex inverter (04), two quad OR's (32), a 1-8 line
decoder (138), three octal d-type latches (374's I think), a dual single
directional buffer (274) and a bidirectional one (275)... and some other
buffer.. can't remember what though.
Fits on a standard SAM board as well...
If anyone wants the postscript (A3 size) schematic for it, let me know...
Si Cooke
