Micromat MM 470A User manual

Manufactured in England by:
MICROMAT INTERNATIONAL
SANDERS LODGE
WELLINGBORO GH ROAD
R SHDEN
NORTHANTS
NN10 6BQ
ENGLAND
Tel : [phone] Intnl : [phone]
Fax : [phone] Intnl : [phone]
web: www.micromat.co.uk email:[email protected]
PCB DRILLING SYSTEM
( MAN AL TOOL CHANGE - AIR )
OPERATOR'S MAN AL
MICROMAT

INTRODUCTION
The Micromat has been designed to enable the drilling and routing of printed
circuit boards to be carried out quickly and efficiently by non-technical
personnel.
The machine is first taught the pattern of holes to be drilled and from then on
the same pattern can be drilled as many times as required until the machine is
re-programmed.
The teaching of these patterns can be by manually programming the machine,
loading data from cassette tape or by downloading CAD drill data from other
computer systems.
If a particular pattern will be required at some time in the future then it may be
saved on cassette tape to be fed back into the machine whenever needed.
Routing profiles can be programmed very quickly and will show a considerable
time saving over conventional sawing or pin routing methods, especially where
small irregular shapes are required.
As with any computer controlled machine, the Micromat will only do what the
operator tells it to do, so in order to obtain the best results its operation must be
fully understood by the operator and the following instructions should be read
carefully, using the machine for reference, until the procedures become
familiar. It is not necessary to actually drill anything to become aware of the
machine's capabilities since use of the CHECK mode allows programs to be
entered and visually inspected with the built in CCTV system. This not only
provides a valuable training aid, but also a necessary testing facility for any
entered programs prior to actual drilling or routing operations.
The Auto Tool Change version offers improved output and accuracy since the
boards do not have to be removed between runs of different drill sizes.
1

INSTALLATION
The drill mechanics must be securely mounted on a flat, rigid surface in order to maintain
the machine's accuracy.
Electrical supplies should be from a direct connection to the main power source of the
building with no other equipment of any kind connected to the same line.
A good electrical ground connection must be made to the machine both to reduce electric
shock hazard and to help prevent electrical disturbances from affecting the operation of the
machine. In some areas it may be necessary to use a power supply filter / regulator unit to
prevent power line interference.
Power requirements:
Electrical Supply 220-230 VAC, 47-63 Hz., single phase @ 10 Amps
Compressed air must be clean and dry and regulated to not more than 80 p.s.i. (5.5 bar)
Although the Micromat will operate under a wide variety of conditions, the machine must
not be subjected to extremes of temperature as this will obviously affect its accuracy.
Temperature changes will also affect the size of any laminate being used. Normal operation
should be at or about 65 degrees Fahrenheit (18 degrees Celsius).
INTERCONNECTIONS
2

ROUTINE SERVICING
The only basic attention required by the Micromat is that it is kept clean and free from dust
and grease.
The swarf extraction unit should be emptied at least daily and the filter bags well shaken to
avoid dust clogging and subsequent overheating and destruction of the motor. The motor
brushes should be inspected monthly and replaced if required.
The X and Y axis bearing rods are accessible beneath the blinds and should be inspected
regularly, wiped with lint free cloth and lightly oiled.
The spindle should have its collet completely removed daily and any traces of dust cleaned
from it and its housing. A build up of dust will cause off-centre rotation, poor quality holes
and a rapid destruction of the spindle bearings. When replacing the collet ensure that the
keyway on the collet engages with the pin in its housing.
From time to time, check that all connectors are secure and that connecting cables are not
frayed in any way.
The tape recorder head, capstan and pinch wheel should be cleaned each week by using
cotton wool buds and methylated spirit or a proprietary tape head cleaning fluid.
3

Section
4
CONTROL SWITCHES AND FUNCTIONS
RESET (momentary action)
Places the control system in an idle mode waiting for a command from one of the following
switches:- M/EXP, HOME, PROG and RUN.
DRILL or M/EXP (momentary action)
If the system is in the PROG mode, then the MOVE or EXPAND routine will be operated.
(See also Section 11). When not in the PROG mode this button operates the drill head
through one complete down/up cycle to enable drill depth and feed rate to be checked.
HOME (momentary action)
Drives both axis of the machine to their HOME (datum zero) position at the top left of the
table and set both X and Y position read-outs to zero.
PROG (PROGRAM) (latching action)
When this switch is depressed the complete control panel is activated to enable a drilling or
routing program to be entered into the control system's memory either manually or by
loading from cassette tape or from a PC via the optional RS232 interface. The program can
be modified and edited in any way required and saved on cassette tape for storage or future
use.
NOTE:- Programs are executed directly from the control system's solid state memory. The
cassette tape is used purely for storage of Drilling or routing data.
RUN (momentary action)
Sets the machine in motion to execute a drilling or routing program which has been entered
into the control system's memory.
CHECK (latching action)
This control modifies the RUN mode to exclude any drilling or routing action so that an
entered program may be checked visually with the TV system. (See also INCR).
HOLD (latching action)
When depressed, this switch will stop the machine in its RUN or CHECK mode. On its
release, the machine will continue to execute the program normally. The HOLD function
also acts as a link between the RUN and PROG modes. (See also INCR and Section 8).
1

Section
5
JOY-STICK
This is used to move the TV target to the position on the circuit board to be drilled or
routed. It should always be moved away from any illuminated INCR buttons to avoid
driving the table to its limit position. If this should happen, HOME must be pressed to
enable further movement.
HOLE (momentary action)
Enters the current position co-ordinates together with the command code for a HOLE and
the current setting of the TOOL SWITCH.
INCR (INCREMENT) (momentary action)
Four of these controls are located round the joy-stick, and a single press will move the
target 2.54 mm (0.1") in the corresponding direction. If the button is held down until a
bleep is heard, the new co-ordinates, together with the command code for a HOLE, will be
entered into memory. If the button is still held down, after a short delay, the target will
continue to move in 2.54mm increments and each position will be entered into memory until
the control is released. The current setting of the TOOL SWITCH will be entered with
each HOLE command.
If CHECK is switched on the INCR distance will be halved. (e.g. 1.27mm)
If HOLD is on during an INCR command then the distance to be moved will be determined
by the setting of the right hand digit of the SIL switch as follows:
SIL HOLD HOLD + CHECK
x1 2.50 mm 1.25 mm
x2 2.40 mm 1.20 mm
x3 2.00 mm 1.00 mm
x4 1.78 mm 0.89 mm Equates to 0.070" for IC packages.
x5 1.60 mm 0.80 mm Use 0.8 for 1.6 mm router offset.
x6 1.50 mm 0.75 mm
x7 1.00 mm 0.50 mm
x8 0.60 mm 0.03 mm
x9 0.10 mm 0.05 mm
x0 ? ? Operator programmable.
SIL switch position '0' can be programmed by the operator for any value from 0.01 mm to
2.56 mm as follows:
1 Ensure PROG is off and press INS.
2 Use the joy-stick to select the required value as a positive number on the X axis DRO.
3 Press any of the INCR buttons.
4 The selected number will remain programmed until the machine is switched off.
(Running a routing program will result in loss of the programmed value)
1

Section
6
TOOL-SWITCH (0-9 selector switch)
This switch is used to enable patterns of different sized holes to be entered into a single
program and to allow the selective drilling of those different sizes according to the setting
of the tool switch when RUN is activated. When using the SST and BST controls, the
display next to the tool switch will show the tool setting that was originally programmed for
each command.
RPT (REPEAT) (momentary action)
Allows a pattern of drilling or routing information to be repeated as often as required on
one panel thereby reducing overall programming time. This function should only be used
when multiple circuits are to be produced on one panel of laminate.
OPEN BRACKET (momentary action)
CLOSE BRACKET (momentary action)
These commands allow operator specified patterns (e.g. for DIL packages) to be repeated
within a program. As many different patterns as required may be entered provided they are
each contained within their own set of BRACKETS. OPEN BRACKET commands specify
the start positions of the pattern and must be followed by the pattern itself, and then a single
CLOSE BRACKET command.
SST (SINGLE STEP) (momentary action)
Allows a program to be checked by advancing one set of co-ordinates at a time and moving
the target to those co-ordinates. The system will not SST past an END command.
(See also Section 9).
BST (BACK STEP) (momentary action)
As for SST but steps backwards through the program. When the start of the program is
reached the bleeper will sound six times. (See also Section 9).
END (momentary action)
This command must be entered at the end of a program to signify that no further
instructions are entered. If omitted, the Micromat will continue past any programmed
information and pull from its memory old data which may destroy the pattern which has
already been drilled.
DEL (DELETE) (momentary action)
A single press will delete the current co-ordinate and command information from the
program and the TV target will move to the next command in the program.
The 'current co-ordinate and command' is the command (HOLE etc) which has been
reached by using the SST and BST controls, is shown on the TV screen and whose actual
co-ordinates are displayed on the DRO.
1

Section
7
INS (INSERT) (momentary action)
When INS is pressed the control system will wait for a command to be entered. This will be
inserted into the program immediately before the current co-ordinate and command which
was reached by using SST and BST and was indicated by the target position.
The position to be inserted must be aligned before the INS key is pressed.
SAVE (momentary action)
Allows the operator to save an entered program on cassette tape for storage or future use.
Pressing SAVE for longer than 2 seconds will access the RS232 software to communicate
with an attached PC.
LOAD (momentary action)
Enables the cassette tape system to load a program into the control system's memory.
Pressing LOAD for longer than 2 seconds will access the RS232 software to communicate
with an attached PC.
When transferring programs to and from cassette tape, the time taken will be 20 seconds
plus 1 minute for every 500 commands in the program.
The memory of the Micromat will store up to 9,800 commands.
Use only top grade C30 computer type data cassettes.
Do not use C60, C90 or C120 audio cassettes.
X Y SWAP
If the X and Y values need to be exchanged to fit the program on to the Micromat table:
1) Press RESET.
2) Switch on PROG.
3) Switch on HOLD.
4) Switch on CHECK.
5) Press and hold LOAD until the tone ends.
6) Press CTRCCW (the left-hand "CTR" command).
7) Press RESET to continue.
X and Y values will then be swapped
1

Section
8
1
ROUTING COMMANDS
DOWN (momentary action)
This button enters the position at which the routing cutter is to be fed into the circuit board
along with the setting of the TOOL SWITCH.
If followed immediately by an UP command the cutter will be fed into the board and then
withdrawn, making a single hole the same diameter as the cutter.
If followed by further DOWN commands, with different co-ordinates, the machine will cut
in straight lines between each pair of DOWN co-ordinates.
DOWN may therefore be regarded as a "Down and stay Down" command until an UP is
programmed.
UP (momentary action)
The UP command is used to enter the position for the cutter to withdraw the cutter from
the board at the end of a straight line cut. The co-ordinate information entered with the UP
command is irrelevant since the command is used only to lift the cutter but the setting of the
TOOL SWITCH is important since UP commands are used in conjunction with previously
entered DOWN commands using the same TOOL SWITCH number.
NOTE:- DOWN and UP commands for the same cut must be programmed with the same
TOOL SWITCH setting.
CUTTING SPEED
The SIL switch is used in the RUN mode to select the cutting speed during routing as
follows:-
10 .. 160 mm/min.
20 .. 175 --
30 .. 190 --
40 .. 210 --
50 .. 240 --
60 .. 275 --
70 .. 320 --
80 .. 385 --
90 .. 480 --
99 .. 645 --

Section
9
CIRCULAR ROUTING
CTR CCW (CTR) (momentary action)
CTR CW (RAD) (momentary action)
The CTRCW (Centre Clockwise) and CTRCCW (Centre Counterclockwise) commands are
used to program the centre point of circles or part circles whose radii must not be greater
than 325.00 mm. The TOOL SWITCH setting is entered with the command.
The button to be used depends upon the required direction of the cutter as it moves round
the circle or arc.
e.g. To program the machine to cut a full circle a total of four commands are required:-
1) a DOWN command at the point where the cutter is to enter the board.
2) a CTR command ( either CCW or CW ) at the centre point of the circle.
3) a second DOWN command at the point at which the circular cut is to finish
( the same point as the first DOWN command for a complete circle ).
4) an UP command to withdraw the cutter from the board at the end of the cut.
As with DOWN and UP commands the DOWN and CTR commands for a given circle must
be programmed with the same TOOL SWITCH setting.
ROUTING ARCS
To cut part circles and arcs, the start and finish points (DOWN commands) must first be
calculated to ensure that their co-ordinates are exactly on the circumference of the circle
whose centre is to be programmed with a CTR(CW) or CTR(CCW) command.
Arcs through 45 degrees and multiples of 45 degrees are simple to program using the DRO
for positional reference as long as the start/finish points of the arcs are at 45 degrees or at
right angles to the machine's axes. Other start/finish points must be calculated to ensure
accuracy.
All points to be programmed for arcs and circles must lie within the programmable table
area of the bed of the machine.
1

Section
10
ROUTING NOTES
An allowance must be made for the cutter diameter in all routing programs.
The INCR function can be used for cutter offset if a value of half the cutter diameter is
selected but will, of course, only be fully effective if used parallel to the axes of the machine.
For best results with the 125 watt spindle, use a 1.6 mm dia. routing cutter with a maximum
stack height of 3.2 mm. Up to 2.4 mm dia and a stack height of 6.4 mm may be used with
the 450 watt spindle.
Use a very slow feed rate to plunge the cutter into the board (use only plunge end cutters)
and a spindle speed of between 35,000 and 45,000 rpm. for the 125 watt 4025 & 4026
spindles.
Use 30,000 to 40,000 rpm for the 450 watt 4032 spindles.
If a high pitched whine is heard then try reducing the cutter rpm. or increasing the cutting
rate.
For smaller cutters, e.g. 1 mm and under, use a higher spindle speed (55,000) and slower
cutting rate.
It must be understood that while routing is taking place there will be an appreciable
deflection of the routing cutter. This is caused by the cutter bending under the load of
routing where only the forward edge of the cutter is in contact with the laminate.
The deflection will vary depending upon the size of the cutter and the linear cutting speed
and could be as much as 0.15mm (0.006") and will cause the bottom board in a stack of
three boards to be cut larger than the top board.
If greater accuracy is required, then the part should be routed in two passes. The second
pass will be cutting only a small amount of laminate and the cutter deflection will therefore
benegligible.
Any measurement of routed parts should be conducted with great caution as changes in
temperature can greatly change the size of a piece of laminate.
1

Section
11
LINEAR ROUTING EXAMPLES
Position No Command
1 DOWN
2 DOWN
3 DOWN
4 DOWN
5 DOWN
5UP
5 END
Note that there are three
commands at position 5.
Positions 1 to 11 are programmed sequentially with DOWN commands at each point.
Position 12 is then programmed with 3 commands:- DOWN, UP and END.
Note that points 6 and 8 are in the same position.
1

Section
12
CIRCULAR ROUTING EXAMPLES
OUTSIDE CIRCLE
Position 1 is programmed with a DOWN command, position 2 with a CTRCW command
and then position 1 again with a DOWN and an UP command at the same position.
INSIDE CIRCLE
As above but position 2
is programmed with CTR CCW
90 DEGREE ARC
Position Command
1 DOWN
2 DOWN
3 CTR CW
4 DOWN
5 DOWN
The lengths of radii 'a' and 'b' must be equal.
1

Section
13
DRILL CHANGE AND DEPTH SETTING
MANUAL TOOL CHANGE SPINDLES TYPE 4025, 4026 AND 4032.
1) Drive mechanics to HOME position and remove TV camera.
2) Unplug the spindle cable and carefully remove the spindle after loosening the two
retaining screws.
3) Position a piece of 0.8 mm laminate under the pressure foot.
4) Operate the HEAD DOWN switch to lower the drill head to its fully down position.
5) Fit the required size drill into the spindle collet with approximately 21 mm protruding.
6) Replace the spindle in the head and gently slide down until the drill tip is just touching
the 0.8 mm laminate. Ensure that the spindle cable exit is aligned at approximately
45 degrees to the pressure foot rods (as shown below) in the case of the 4025 spindle,
and re-tighten the two spindle retaining screws.
7) Re-connect the spindle cable and release the head down switch.
The drill fully down position (HEAD DOWN switch) is now set to 0.8 mm above the bed of
the machine and a backup material of greater than 1.6 mm should be used to ensure that the
drill will pass completely through the circuit board. For large diameter drills (above 2 mm)
the backup material thickness should be increased unless the drills have flat tips.
1

Section
14
TV TARGET ALIGNMENT
1/ Allow 30 minutes TV warm up time.
2/ Press PROG and allow the machine to travel to its HOME position.
3/ Pin a piece of unclad laminate and backup material to the drilling bed.
4/ Using the joy-stick, (see Section 1), position the TV target over the laminate
and enter six holes by holding down one of the INCR buttons for six bleeps, ensuring
that the target is still over the laminate, and then press END.
5/ Release PROG.
6/ Press HOME and set the drill depth with a drill diameter of approximately 1.5 mm.
7/ Set FEED RATE toslow
8/ Set spindle speed to 40,000 rpm and test drill action by ensuring that the PROGRAM
mode is switched off and pressing DRILL (M/EXP)
9/ Press RUN.
After the machine has drilled the six holes and returned HOME, refit the TV camera and
press PROG and then SST. The TV will move to show the first hole on the monitor screen.
Adjust the camera focus slide to give a clear picture and centre the target over the hole by
adjusting the two controls on the camera. Then, using the SST and BST controls, move the
target over the six drilled holes and readjust the target alignment if necessary.
The TV target colour can be changed from black to white for optimum viewing contrast
with the switch fitted to the TV monitor.
NOTE:- The camera should be removed for normal drilling and routing to avoid any
vibration damage.
1

Section
15
HOW TO ENTER A PROGRAM
In order to fully understand the operation of the Micromat, it is strongly advised that these
instructions are followed step by step until the procedures become second nature to the
operator. The basic controls will be dealt with first, and after becoming fully conversant
with these the operator should progress to the section covering RPT, BRACKET, SIL,
MOVE, EXPAND and ASCOPP commands.
It is assumed that sections 2 and 3 covering tool installation, drill depth and TV target
adjustment have been read and understood.
Select a small circuit board with no more than about 50 hole positions to become familiar
with the operation of the Micromat computer and mechanical system.
Resist the temptation to go straight into full production without first acquiring a full
operating knowledge of the complete machine as costly mistakes, both in time as well as
materials, will result from an incomplete understanding of the operating principles. A few
hours spent at this stage will save many hours of frustration at a later date.
Each time the PROGRAM mode is entered, ( as long as the HOLD switch is OFF ), the
system will reset itself to the first block of program memory, regardless of any previously
entered data, and the first command to be entered is placed in that first block of memory.
Each subsequently entered command is placed sequentially into each succeeding block of
memory in the order in which the commands are entered.
When the machine is first switched on, it's memory will contain information which is
meaningless and should be ignored as it will be overwritten in the course of entering new
data.
Because of this feature there is no requirement to 'clear' the system's memory, nor is there
any means of doing so as the machine simply runs until it encounters an END command.
When a program is RUN, operation normally starts with the FIRST block of data and
continues sequentially, in the order in which data was entered, until an END command is
encountered. The END command prevents the system from accessing memory blocks
which have not been programmed and may contain unwanted or non valid commands.
The correct order in which to enter commands is:
a) any tooling or panel registration holes.
b) followed by RPT commands if required.
c) HOLES of each required tool size along with any BRACKET commands.
d) finally a single END command.
NOTE: ONLY ONE END COMMAND IS REQUIRED.
2

Section
16
ENTERING DRILLING INFORMATION
Please set the TOOL SWITCH to "1" before continuing.
OPERATOR ACTION MACHINE RESPONSE
1) Press PROG. a) Lights on PROG come on.
b) Both axes move to HOME.
c) Lights on the left-hand and top
INCR buttons come on to show
that the table is within 3 mm of
its limits. Do not enter any
program information if any of
these are on.
2) Position artwork, or
board to be copied, on
the tooling strips.
3) Having determined the
best drilling sequence,
use the joy-stick to
position the TV target
over the centre of the
first hole to be drilled.
The joy-stick must always be moved away from any illuminated INCR buttons to prevent
the table being driven to its limit stops. If this should happen part way through a program,
press HOME and then BST and the target will be driven to the last position which was
programmed. This command must be re-entered before continuing. If it is done at the start
of a program then a reset will restore control to the joy-stick and the system will re-enter
the PROG mode.
4) Press hole once. A single bleep will be heard
to show that the location of
the hole has been fed into
the machine's memory.
5) Continue moving the Bleep. . . . . . . . . . . .
target and pressing HOLE
until the last position
has been entered.
6) Press END once. Bleep.
The Micromat is now programmed to drill the hole pattern which has just been entered.
3

Section
17
The program should be checked for accuracy BEFORE DRILLING as follows:-
7) Press BST once quickly. a) End light will come on.
b) The bleeper will sound
continuous bleeps.
c) The target will not move.
8) Press BST once quickly a) The END light will go off.
b) The bleeper will go off.
c) The target will position
over the last hole in the
program and the hole light
will come on, and the tool
display will show a "1"
to indicate the programmed
tool number.
9) Press BST once quickly The target will move to the
previous hole in the program
and the bleeper will sound
as the button is pressed
and again, as the position
is reached.
10) Continue pressing BST. The target will move from
( or hold BST down ) hole to hole until the first
command of the program is
reached when seven bleeps
will be heard.
The SST (Single Step) button is used in the same way as BST but will advance through the
program towards the end command. When this is reached, the END light will come on and
the bleeper will sound continuous bleeps. SST will have no further effect.
If the reset button is pressed while the machine is in the program mode (PROG button
depressed) the control system will re-enter the PROG mode on its release, and subsequent
SST commands will step through the program beginning with the first hole, or other
command, which was entered.
If any of the HOLE positions need to be altered they are simply repositioned after being
reached by using BST and SST and re-entered by pressing HOLE. Any other command
may be repositioned in the same manner. Care should be taken to re-enter the correct
TOOL number.
SST can also be used to SEARCH for a previously entered position. (See Section 9).
4

Section
18
DELETE
Unwanted commands can be removed from the program be pressing DEL (DELETE)
immediately after the unwanted position has been reached with BST and SST. The
information is deleted from the program when the DEL button is released. This action is
indicated by a long bleep and the TV target will move forward through the program to the
next position.
An END command must first be re-programmed as some other command, (e.g. HOLE),
before it may be deleted.
INSERT
Fresh information can be inserted into the program at any point by using the INS (INSERT)
key. The new command will be entered immediately before the current command as
reached by BST and SST.
e.g. To insert a new hole between the 5th and 6th holes of a program:
a) Use SST or BST to reach 6th hole of the program.
b) Move the target to the new position to be inserted.
c) Press INS. (The INS light will come on).
d) Ensure that the correct tool size is selected and press whichever command is required
(e.g. HOLE) and after a bleep the INS light will go out to show that the fresh command
has been inserted.
In the above example the inserted hole will become the new 6th hole. The old 6th hole will
become the new 7th hole, the old 7th will become the new 8th and so on, right through the
program to the END.
Note:- After the INS key has been pressed, the target cannot be moved until after a
command has been entered. To allow movement without having to enter a command, press
DEL and the INS light will go out. Inserted commands will not self-centre whilst being
inserted.
Practice moving various programmed positions, deleting and inserting, but initially, only
attempt to move, delete or insert one position at a time, learning what happens when SST
and BST are used immediately after each operation.
Try re-programming some of the positions with different tool sizes and try using the
CHECK-RUN function to view the result of running with different TOOL SWITCH
settings.
If PROG is not released before RUN is pressed, the program will not start at the beginning,
but with the position which was displayed on the monitor when RUN was pressed.
PRACTICE MAKES PERFECT
4

Section
19
DRILLING THE PATTERN
The Micromat is able to drill the pattern of holes as follows:-
1) Release the PROG switch.
2) Press HOME.
3) Remove TV camera.
4) Replace the artwork with blank laminate and backup material pinned to the tool strips.
5) Set spindle speed, feed rate and depth to suit the drill size and material height.
6) Ensure the TOOL SWITCH is set to select the holes to be drilled and press RUN.
The spindle and extract systems will switch on and after a short delay, the table will go
home before moving through the programmed positions to drill the board. On completion
of the program, the drill and extract systems will switch off and the table will return to its
HOME position. The END light will come on and the bleeper will sound continuous
bleeps. The bleeper can be canceled by pressing RESET without affecting the stored
program in any way.
7) Fit a fresh blank and press RUN to drill another board.
OR
8) Press RESET to cancel the END light and bleeper.
The program will remain in the control systems memory until a new one is entered or the
machine is switched off. In the case of systems fitted with a battery backed memory the
data will remain valid for at least 1 month or until the program is overwritten by a new one.
The battery backed memory allows recovery of data in the event of a power failure before
the finished program has been SAVED.
Programs can be checked by using RUN but the CHECK switch depressed. The target will
be driven through the program and hesitate to show each position on the monitor before
reaching the END and returning HOME.
If PROG is not released before RUN is pressed then the program will not start at the
beginning, but with the position shown on the monitor when RUN was pressed.
(See also Section 8)
4