@NewPage
@Section(EUCSD MOTOROLA M6809 ASSEMBLER)

This assembler is a local implementation of the  Motorola  M6809  cross
assembler.   This  is  basically  documented  in the 'M6800 Microprocessor
Programming Manual' with the extensions for the  M6809  described  in  the
'M6809  Advance  Information' data sheet.   Wherever possible it is upward
compatible with the Motorola assembler and  like  it,  contains  no  macro
facilites.


@SubSection(Differences)

@Paragraph(Restrictions)
@Begin(enumerate)
Only one program may be assembled in a single input stream.  As a
result the MON and END directives are synonymous and optional.

Only object tapes are produced by the assembler.  As a result the
OPT  directive  options  MEMORY  and OTAPE and their variants are
illegal.

Error messages are of a different and fixed form  and  hence  the
OPT directive options SERROR and SER are synonymous with ERROR.
@end(enumerate)

@Paragraph(Extensions)
@Begin(enumerate)
The  delimited  form  of  the  FCC directive accepts the doubled
delimiter as a single instance of the delimiter in the  generated
text.
@Begin(Fileexample)
e.g.                     FCC   /A//B/
is the same as           FCC   'A/B'
@end(Fileexample)

The OPT directive has the following additional options:
@Begin(Fileexample, LeftMargin +2)
Long form  Short form   

BLANK      B      Ignores   redundant   spaces  in  operand
                  field. e.g. around ',' and '+'.

NOBLANK    NOB    No  spaces  allowed  in   operand   field
                  (selected by default).

CYCLE      C      Print  execution  time  in machine cycles
                  for each executable statement.

NOCYCLE    NOC    No execution times printed  (selected  by
                  default).

FULL       F      Allows   fully  parenthesised  arithmetic
                  expressions as operands (see (3) below).

NOFULL     NOF    Only     unparenthesised      expressions
                  evaluated strictly from left to right are
                  allowed    as   operands   (selected   by
                  default).

WRAP       W      Long input lines are wrapped around on to
                  next line of listing.

NOWRAP     NOW    Long input lines are truncated in listing
                  (selected by default).

XREF       X      Symbol cross reference is listed  at  end
                  of listing.

NOXREF     NOX    No   cross  reference  table  is  printed
                  (selected by default).
@end(Fileexample)

By  specifying  OPT   FULL,   fully   parenthesised   arithmetic
expressions evaluated in the usual algebraic order are acceptable
as operands.  The valid binary operators are (in increasing order
of precedence):
@Begin(Fileexample)
! (or), \ (exclusive or)
& (and)
+, -
*, /, | (remainder)
< (left shift), > (right shift)
@end(Fileexample)
The  unary  operators  +  (ignored),  -  and  \  (complement) are
accepted and take precedence over all binary operators.

A  '>'  expression  prefix  is  provided  which  forces  extended
addressing.   This is the converse of the '<' prefix which forces
direct addressing.

The program counter relative address mode  may  be  specified  by
offset,pc   as   well   as   label,pcr.    The  former  does  not
automatically generate a relative offset from an absolute address
but takes the value of the offset expression as the  offset  from
the updated program counter.   For Example, the following program
segments are equivalent:
@Begin(Fileexample)
lab    nop
jmp   lab,pcr

lab    nop
jmp   lab-nxtins,pc
nxtins equ   *
@end(Fileexample)

Apart from catastrophic failures, error messages are generated in
the final pass only and always immediately  follow  the  line  to
which they apply.

This is a multi-pass assembler in which there are no constraints
on the order of definition  of  symbols  and  which  attempts  to
optimise  the use of direct addressing and short branches.   As a
result the mnemonics for long and short branches  are  considered
synonymous except for BRN and LBRN.
@end(enumerate)

@Subsection(Implementations)

VAX and APM

M6809 file-spec
@Begin(Fileexample, LeftMargin +0)
Command Qualifiers         Default

/[NO]LIST[=file-spec]      /NOLIST
/[NO]OBJECT[=file-spec]    /OBJECT
@end(Fileexample)
Command Parameters

file-spec

Specifies  a  single  M6809  assembler  source  program  to be
assembled.   If a file type is not specified the  assembler  uses
the default file type ASM.

Command Qualifiers
@Begin(Fileexample, LeftMargin +0)
/LIST=[file-spec]
/NOLIST
@end(Fileexample)
Controls whether a listing is produced.

If  file-spec  is  not specified the listing file has the same
name as the source file and has the file type LIS.
@Begin(Fileexample, LeftMargin +0)
/OBJECT=[file-spec]
/NOOBJECT
@end(Fileexample)
Controls whether an object code file is produced.

If file-spec is not specified the object  file  has  the  same
name  as  the source file and has the file type OBJ.   The object
code produced is in Motorola M6800 loader format.

@Begin(Comment)
@Section[Programming (Blowing) EPROMS for the CS2 Microkit Exercises]

First prepare your program in M6809 assembly language, editing it  into
a file of type ASM (e.g. TEST.ASM).  Because within the microkit the EPROM
occupies  that  part  of  the  address  space between $F800 and $FFFF, you
should ensure, by appropriate use of the ORG directive, that all generated
code and data lie within those limits.

Next you should assemble the program using the command  M6809,  as  per
the instructions given above.

You  are  now  ready to send your object file to one of the programming
devices which are located in the North-West corner  partition  of  the  CS
North  Machine Hall (JCMB room 1206, affectionately known variously as the
"darkroom" or the "Fred-laboratory").   The two devices (Microware  models
32 and 33) are slightly different, but have the major instruction steps in
common:
@Begin(Fileexample)
Configure device
Select and insert EPROM
Prepare device to receive
Send file (from VAX or APM)
Instruct device to program EPROM
Remove EPROM
@end(Fileexample)
@SubSection(Instructions in detail)

@Paragraph(Configure device)

You should make sure the device is configured to program the right sort
of  EPROM, this should be a "2716" or "2516".   The model 33 has large (24
pin) red or blue configuration plugs which fit into the black socket  just
above  the green one.   The model 32 has small (16 pin) red or blue plugs.
Both models also have small (14 pin) configuration plugs which fit into  a
socket near the upper left hand side of the device.  These latter ones are
irrelevant  for  programming operations and the corner sockets are usually
left empty.  Take care, in the case of the model 32, not to confuse the 14
pin and 16 pin configuration plugs.   The ones to use are marked with  two
horizontal white stripes just above and below the EPROM type number.

@Paragraph(Select and insert EPROM)

You  have  to  insert a fresh EPROM into the green Zero Insertion Force
(ZIF) socket on the device.   Make sure the EPROM you plug in  is  of  the
correct type "2716" or "2516".   The lever on the upper right-hand side of
the socket should be in the raised position before you  insert  the  EPROM
into the socket.   The small semi-circular notch on the EPROM should be on
the left-hand side, facing away from  the  lever.   After  insertion,  the
lever  should  be  moved  through 90 degrees to a position parallel to the
large surface of the socket.

@Paragraph(Prepare to receive)

You have to prepare the device to receive  the  object  file.   On  the
model  32,  press  the  red 'F' (function) button followed by the grey 'A'
button ('A' stands for serial input, see the table printed on the device).
On the model 33, the procedure is a bit more complicated.   Press the  red
'RSET'  button  followed  by  the  red 'SEL' button (the display will show
"SELECT?").   Then press the grey button  marked  'LD'  (above  'A')  (the
display will show "RS232?", asking you for the terminal line baud rate etc
code).   Then  press  the four buttons '0', '1', 'E', 'ENTER' (the display
will show "INPUT?", indicating that it is ready for the file to be sent).

@Paragraph(Send file from VAX or APM)

Use the command SEND32 or SEND33 (depending on which of the programming
devices you are using), with the name of the object file as parameter (the
file type OBJ is assumed and should not be mentioned explicitly).
@Begin(Fileexample)
Example:     $ SEND33 TEST
@end(Fileexample)
The object file is sent to the device through the Visual 200 terminal  you
are  using,  but the information does not appear on the screen.   When you
have come back to command level, the file will be in the device's  memory.
The  display  of the model 22 will show two hex digits, being the contents
of the first location ($F800) in the EPROM.   The display of the model  33
will  jitter  during the transfer, but at the end will revert to "INPUT?".
If the display should start flashing during the transfer, this indicates a
transmission error and you should try again (go back to C).

@Paragraph(Instruct device to program EPROM)

Now you must tell the device to program the contents of its memory into
the EPROM you have plugged in.   On the model 32 proceed as follows: Press
red  'F'  followed  by  '9'  ('9'  stands for 'fast program', which is not
mentioned on the printed table, but '8', which stands for 'program',  is).
The  display  will  show  a  quickly  counting pattern, for about 10 to 20
seconds, and then stop.   If it flashes, something went wrong, you can try
again  from  (E),  or  else  try a different EPROM (steps F, B, E).   When
trying a different EPROM it is not necessary to repeat steps (C, D), since
the object file contents are already in the device's memory.
Function '9' is a non-standard locally-implemented extension.  Function
'8' is the officially recommended method, but takes about 130 seconds.  We
have found that for our purposes 15 seconds are usually enough to  program
the EPROM reliably.

On  the model 33 proceed as follows: Press 'RSET' then 'SEL' then 'PRG'
(above '8').   The display will show "PWR ON" and a red lamp  between  the
configuration  plug  and  the  ZIF  socket  will  light.   The programming
operation will take about 200 seconds, after which the display will revert
to showing a few hex digits.   If it flashes, something  went  wrong,  try
again (E) or (F, B, E).

For  the  model  33 there is no 'fast program' function, so, unless you
want to wait more than 3 minutes, you  should  interrupt  the  programming
operation  after  15  to  20 seconds, and ask the device to verify that its
memory contents agree with the EPROM contents.   Here's how:  Press 'RSET'
then  'SEL' then 'VER' (above '3').   If the display flashes, something is
wrong, you probably interrupted it too soon, go back to  (E)  for  another
ten seconds.  If it still fails, try another EPROM (F, B, E).

@Paragraph(Remove EPROM)

Finally, remove the EPROM from the ZIF socket.   Tilt the lever back to
the upright position and lift the EPROM out vertically.  After having used
the EPROM in the microkit, return it to the tray near the erasing lamp.

@SubSection(Instruction summaries)
@Begin(Fileexample)
@b[Model 32                                Model 33]

Red F                                   Red RSET
Grey A                                  Red SEL
"SEND32"                                Grey LD/A
Red F                                   Grey 0
Grey 9                                  Grey 1
Wait 20 secs                            Grey E
Display should have stopped counting    Blue ENTER
"SEND33"
Red RSET
Red SEL
Grey PRG/8
Wait 20 secs
Red RSET
Red SEL
Grey VER/3
Should not flash
@end(Fileexample)
@end(comment)