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\fBUsing the SMARTWATCH(TM) with the XDROM in gate-array Model 4/4D systems\fR
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Copyright 1991, M. A. D. Software, All Rights Reserved.
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There are three methods of utilizing a SMARTWATCH with the XDROM.  Each
method requires hardware modifications or places limitations on your system.

M. A. D. Software normally uses a 2764 EPROM (Electrically Programmable Read
Only Memory) for the XDROM.  This is a commonly-available, high speed
EPROM, but has a pin organization that is incompatible
with the pin organization of the original "D" ROM.  To allow the 2764 to be
used, an adapter is provided that rearranges the pin-out so that the 2764 can
be used.   The 2764 will support Model 4/4D systems running as fast as 8MHz
with no wait states.  (Other components in the system may not be able to
handle this speed, however.)

The 68764/68766 EPROM is pin-compatible with the original "D" ROM, but was
only manufactured by one company and it does not meet the speed requirements
of Model 4/4D systems that have been modified to run faster than 4MHz.
In addition, the 68764/68766 are now becoming hard-to-get and are expensive.

To add a SMARTWATCH to a system using the XDROM, the following
alternatives are available:

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1.	Plug the SMARTWATCH into the XDROM adapter.  No jumper wires are
required, as the SMARTWATCH is pin-compatible with the 2764, which
is the type of EPROM that is used with the adapter.

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The problem with this alternative is that the combination of
adapter, EPROM,
and SMARTWATCH is too tall to fit under the RF-shield, and in
some cases, the cover itself may not fit.   If the only problem is that
the RF-shield is in the way (the plastic cover will still fit,
you could cut a small hole in the RF-shield over the XDROM adapter.
You should not run your system without the RF-shield in place.
Failure to do so can cause radio and TV interference which you 
are required (by law) to correct.

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2.	Use a 68764/68766 EPROM instead of the adapter and the 2764 EPROM.
M. A. D. Software will exchange the adapter and 2764 for a 68764/68766
EPROM on request.  The SMARTWATCH would then be used in the "D" ROM
socket as before (same straps and jumpers are required).  However,
systems using the 68764/68766 will not be able to fully utilize any
speed modifications that have been made to the system.
	
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For example, if you have an XLR8er adapter, you must run with at least
one (1) memory wait state when running in Model III mode.  There is no
additional restriction on the number of wait states in Model 4 mode.
If you are currently able to use zero (0) wait states in Model 4 mode,
you may continue to do so.

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If you have directly modified your system to run the Z80 at a speed
higher than 4MHz, you may not be able to use the 68764/68766 EPROM.
An EPROM memory cycle must be at least 400 nsec, which means that you
may have to add additional wait states or operate at a reduced speed
while in Model III mode (this includes the booting period for
Model 4 mode).  The Model III mode CPU speed cannot exceed 5MHz.
Once you have entered Model 4 mode, you can increase the speed.
(If you want the BOOT command to work in Model 4 mode, you will have to
reduce the speed prior to giving this command, as it places the machine in
Model III mode.)

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3.	Place the SMARTWATCH in the "A" ROM socket.  This solution allows the
XDROM (2764) and adapter to be placed in the "D" ROM socket, and the
"A" ROM and SMARTWATCH reside in the "A" ROM socket.   You may operate
your system at any speed you ran it at previously, and the RF-shield
should not be hampered by the XDROM and its adapter.  The SMARTWATCH
will still be the tallest item.

The only problem with this arrangement is that several jumpers, or
"flying wires" are required to use the SMARTWATCH in the "A" ROM socket.
You will need a soldering iron and some fine wire to apply these
modifications.  If you already have jumpers on your SMARTWATCH,
read over these instructions, as some of the jumpers are probably
identical to the ones you have now.


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SMARTWATCH is a trademark of Dallas Semiconductor

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Instructions for installing the SMARTWATCH in the "A" ROM socket.

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1.	On the bottom of the SMARTWATCH, connect a jumper wire between
pins 26 and 28.  Note that pin 26 must still plug into a
socket, so make your connection next to the body of the
SMARTWATCH and be neat.

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2.	Bend pin 20 of the SMARTWATCH outwards, so that it will
not plug into the socket later on.

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3.	Bend pin 22 of the SMARTWATCH outwards, so that it will
not plug into the socket.

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4.	Connect a jumper wire between pin 20 and pin 22 of the 
SMARTWATCH.  This can be underneath the SMARTWATCH.  An additional
wire will be attached to pin 22 in the next step.

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5.	Connect a jumper wire between pin 6 of U45 (a 7408, located
below and to the right of the "A" ROM socket) and
pin 22 of the SMARTWATCH.  There are now two wires on pin 22.

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6.	Remove the "A" ROM from its socket, U29 (located below
the "D" ROM socket).

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7.	Remove U5, a 40 pin chip labeled "4.2".  Bend pin 21
(lower right) outwards so that it will not plug into the
socket.

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8.	Bend pin 20 of the "A" ROM outwards so that it will not
go back into the socket.

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9.	Connect a jumper wire between pin 20 of the "A" ROM and
pin 21 of the "4.2" chip.  Make sure the wire is long
enough to reach once both chips are reinstalled.

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10.	Re-insert the "4.2" part into U5.  Make sure all pins 
(except pin 21) are properly aligned and go into the socket.

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11.	Bend pin 18 of the "A" ROM outwards so that it will not
go back into the socket.

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12.	Remove the jumper clip on JP8/JP9.

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13	Connect a jumper wire between the center pin of JP8/JP9 and
pin 18 of the "A" ROM.  Make sure you can get the jumper clip
back over the JP8/JP9 pins when you are done.

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14.	Install the jumper clip in the JP8 position, on top of
the wire installed in step 13.

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15.	Remove the XDROM from its adapter.  Bend pin 22 of the
XDROM (NOT THE ADAPTER) outwards so that the pin will not
go back into the adapter.

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16.	Using a small (half-inch) piece of 24 or 26 AWG wire, insert
one end of the wire into socket position 20 of the SMARTWATCH.
Then fold this wire inwards so that it lies flat over the
center of the SMARTWATCH.  If it extends far enough to touch pins
on the other side of the SMARTWATCH, cut the wire shorter.

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17.	Connect a jumper wire between pin 22 of the XDROM and the
piece of wire inserted to socket position 20 of the SMARTWATCH.

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18.	Re-install the XDROM into the adapter.  This can take a
little time.  The chip will insert easily, but only if
all the pins are centered in the socket-cups.  You may
have to adjust one pin at a time.

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19.	Once the XDROM is installed in the adapter, make sure
pin 22 is still sticking out and is not touching the contacts on the adapter.

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20.	Insert the "A" ROM into the SMARTWATCH, placing pin 1
of the "A" ROM in position 3 of the SMARTWATCH socket.  The wire connecting
to socket position 20 in the SMARTWATCH should be routed between the two
rows of pins.

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21.	Once the "A" ROM is installed in the SMARTWATCH, confirm
that pins 18 and 20 of the "A" ROM are still sticking
over the sides of the SMARTWATCH.  Pay extra attention to pin 18, making
sure it does not make contact with the wire inserted into the SMARTWATCH
underneath.

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22.	Install the SMARTWATCH into the "A" ROM socket on the
CPU board, placing pin 3 of the SMARTWATCH into position 1
of the socket.  Pins 1, 2, 27 and 28 should be hanging
over the side.

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23.	Now confirm that pins 20 and 22 of the SMARTWATCH are
sticking over the side of the CPU board socket.

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24.	If you removed the XDROM and adapter from the "D" ROM
socket, reinstall it now.

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25.	At this point, you should have the following wires
installed:  (Recheck your connections)

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1.	SMARTWATCH pin 28 to SMARTWATCH pin 26.

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2.	SMARTWATCH pin 20 to SMARTWATCH pin 22.
Pins 20 and 22 do not go into the "A" ROM socket.

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3.	SMARTWATCH pin 22 to U45 pin 6.
Pin 22 does not go into the "A" ROM socket.

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4.	"A" ROM pin 20 to "4.2" chip in U5, pin 21.
Pin 20 does not go into the SMARTWATCH socket.  Pin 21
does not go into the U5 socket.

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5.	"A" ROM pin 18 to center pin of JP8/JP9 jumpers.
Pin 18 does not go into the SMARTWATCH socket.

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6.	SMARTWATCH socket position pin 20 to XDROM pin 22.  Pin 22
does not go into the XDROM adapter.

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The SMARTWATCH should now work as it did when it was installed in
the "D" ROM socket.
























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