Lexicon MPX-1 Technical Manual page 18

the transfer to occur at a much higher rate. Three addresses are passed: The
starting address of the block to be moved. its ending address and the destina-
tion address of where it's being moved to. Each address is three bytes long and
is stored low byte first. The starting address should be at Parameter Bytes 0-
2, the ending address should be at Parameter Bytes 3-5 and the destination
address should be at Parameter Bytes 6-8. Note that even though each aadress is
three bytes long, the low byte is assumed to be 00 hex.
RESERVED - DO NOT USE
OPCODE BIT CODING:
Bit 7
CONT
I
INT
o o
1 1 1
Bit 0
1
Note: This opcode is reserved and should not be used by custom command
routines. At tempts to call this opcode will be translated internally to NOP
opcodes (link address will still be valid. however). The reason this opcode is
reserved is because its jump table address is used by the ATTN routine.
&lInn",
'PUll'
unv I'nnll
J.oca~l.ons
are l.nl.[:l.al.l.zeo
[:0
pol.n[:
[:0
a
X-OULl.Tlt:!
l;i:l.J•
.Lt:U UU."U"l.L. Wll.L"ll
.Ll:> l l U L l l . L ' - ' 6
more than a RET instruction. This is where all interrupts and all unused
commands go to. (until you change the table). The next thing that happens is to
patch the command jump table with the addresses of the ten command routines that
are supplied in the ROM. Next the stack pointer is initialized leaving about 77
bytes free for stack usage. That should be more than enough, the routines in
the ROM never get more than about 6 bytes deep•
.
Next the initial link address is set up to point address SOH and then the
ATTN interrupt (RST 7.5) is armed and the MPX sits quietly waiting for an ATTN.
19