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Software Write Protect
IK blocks of memory m a y Be write protected or xmprotected with
an OUT command to port FE*.
block is selected with the high->-order 6 Bits in the output data
word.
Bits 0 and 1 select the function (Protect, Unprotect,
Select Board for Status of Clear Interrupt!.
should be the same as bits 10 through 15 of the memory address
of the desired IK block.
board and bits 2 and 3 select the IK block on that board.
to Table 2 for bit functions.
Output
Data
Bit
7*1
Board
6 1
Select •
5
1
4 J
»
3 \
IK Block
1 Select
2
\ Function
1
Select
0
1
Bit 0
Bit 1
0
0
1
0
0
1
-
1
1
The output command to select a board for status read must be
issued before each status read.
board to respond with status to the next INP command from port
FE.
The board automatically deselects after responding to the
INP command.
Care should be taken not to select more than one
board before reading the status or the boards will interfer- with
each other.
Refer to Table 3 for the meaning of the status data
bits.
* This address may be changed if desired by using the inverters
in C7 (pins 1, 2, 3, 4).
pins to D
and solder jumpers to the spare inverter.
6
verter line A
bit.
Be sure to reconnect bit A
18
Selection of memory Board and
Bits 4 through 7 select the memory
TABBE 2
Same as
Memory Address
Bits for desired
IK Block
.
Clear Interrupt
Unprotect Addressed Block
Protect Addressed Block
Select Board for Status Read
Cut the trace to the desired input
may similarly be"removed and placed in another
8
RAM 4A
User Guide
Bits 2 through 7
f15
14
13
12
'
11
1 0
This enables the selected
.
8
Refer
The in
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