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Antoine Vignau 4d4fb6a665 Let's free the code!! 
Some old (WIP) disassemblies and my own source code now available online.
2024-07-23 23:38:22 +02:00

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S-C Macro Assembler
VERSION 2.0
S-C Software Corporation
2331 Gus Thomasson, Suite 125
P.O. Box 280300
Dallas, Texas 75228
(214) 324-2050
---------------------------------------------------------------------
S-C Macro Assembler Version 2.0
Here is your copy of the latest upgrade to the S-C Macro Assembler.
The most important new feature of Version 2.0 is the capability of
assembling the enhanced instruction sets of the 65C02 (both standard
and Rockwell editions), 65802, and 65816 microprocessors. Next in
importance is the revision of I/O handling to make it easier for you
to customize the I/O driver for any sort of 80-column card you may
have. 80-column drivers are included for the IIe, //c, Videx, and
STB80 systems. In addition, Version 2.0 also includes many small
enhancements which will be detailed herein. This upgrade packet also
describes the additional features added vith versions 1.1 and 1.2.
The disk contains two versions of the S-C Macro Asseubier: one which
loads at $1000, and another which loads at $D000. These versions are
configured with a 40-column driver vhich viii vork in any Apple II
series computer having at least 48K ($1000 version) or 64K ($D000
version) of RAM. I recommend, although it is not absolutely
necessary, that Applesoft be resident in ROM on the motherboard.
The HELLO program checks to see whether you have an Apple IIe, //c,
or older version. If it is not a IIe or //c, HELLO next presents a
menu for you to choose a 40-column, Videx, or STB-80 version.
Following that choice, you are presented vith a menu to select the
$1000 or $D000 version of the assembler. With all choices made,
HELLO loads the selected version of the assembler, and then BLOADs the
selected driver (if any). The $D000 version is more complicaed to load,
so it is controlled by an EXEC file.
As is true of all S-C products. the Version 2.0 disk is not
copy-protected in any vay. Make a backup copy now, and store the
original in a safe place. The standard Apple COPYA is included on
our release disk for your convenience. You may also use the FID
program to make copies of your working disks.
You will probably wish to move the version of the assembler you
usually use, with your favorite driver and EXEC loader, to your
working disks. Do it!
It is also possible and advantageous to burn the assembler into
EPROM. Some owners have burned it into 2716's for installation into
an Apple firmware card; others have burned it into 2764's or a 27128
to plug into the SCRG quikLoader. We have done the latter too, and
you may purchase a 27128 from us with Version 2.0 in it. Call for
details.
- 1 -
---------------------------------------------------------------------
DOS Version
The release disk contains a slightly modified version of DOS 3.3. It
is not the latest version of DOS 3.3 as distributed by Apple (which
included some "final" patches for the APPEND command). Our version
includes instead some patches which speed up the LOAD, BLOAD, and RUN
commands tremendously. Of course, the S-C Macro Assembler will run
with any version of Apple DOS 3.3, with or without our patches.
However, it may not work with some of the enhanced DOS products. You
should have no trouble with ProntoDOS, DavidDOS, or The DOS Enhancer;
but some other brands, including DiversiDOS, are known to conflict
with our use of DOS when you use the .TF assembler directive.
Version 2.0 is compatible with the Corvus hard disk system; it has
not been tested with other brands. If there is a problem with other
brands, it will occur during assembly of programs which use both the
.IN and .TF directives with the files residing in different volumes
on the hard disk.
I/O Drivers
The copies of the Version 2.0 on the release disk include 40-column
display drivers. The release disk also includes the source and
object code for three 80-column drivers. The HELLO program will
automatically BLOAD the 80-column driver of your choice. They are up
to 244 bytes long, and load at either $3700 with the $1000-based
assembler or $F700 with the $D000-based assembler.
Once you have the assembler in memory with your selected driver, you
could BSAVE the composite as your own private version. Use your own
file name, an address of $1000 or $D000, and a length of $27F4.
I have attempted to make operation identical regardless of which
driver is in place. Nevertheless, there are still some differences.
The constraints of 244 bytes per driver, sometimes "crazy" firmware,
and the wide variety of features have meant compromises. Since you
will probably settle on just one version, the minor differences
between it and the ones you do not use should cause no problems.
1. //e-//c Driver:
The best version is the //e version, running in either a //c or in a
//e with the new CDEF ROM set (copyright 1984). All features work
well with this configuration. When the assembler with this driver is
loaded, the screen stays in whatever mode was already set. If you
were in 40-column mode, it stays in 40-column; if in 80, it stays it
80. Once in the assembler, you can go to 80-columns by typing PR#3,
or back to 40-columns by hitting ctrl-RESET. In a //e with the older
firmware, you can also revert to 40-columns by typing esc-crtl-Q. In
a //c
- 2 -
---------------------------------------------------------------------
or a //e with the new firmware, esc-ctrl-Q does nothing; however, you
can revert to 40-columns by typing PR#0.
In a //e or //c, you may leave the assembler by typing the FP
command. If you are using the $D000-based version, you may return to
the assembler with the INT command. (The INT command cold starts the
assembler, just as it would cold-start Integer BASIC if that language
were loaded into the $D000 area. This means any source program
which may have been in memory earlier is cleared.)
If you wish to engage a printer, first get into the 40-column node.
Then type PR#1 (or PR# and whatever slot your printer card is in).'
After the printing is complete, you may return to 80-column mode.
Usually, 80-column screen display and printer interfaces should not
be mixed.
There is one thorny configuration that you may possibly have: The
older //e firmware with the MouseText character generator ROM. With
this configuration, inverse capital letters appear on the screen as
MouseText icons. The alternative is to turn off the ALTCHRSET mode,
in which case inverse letters appear as flashing letters. If this is
your configuration, hopefully you will upgrade your firmware as soon
as Apple's upgrade kit is available.
The older //e firmware handled the "escape" key in a very difficult
manner, so that I cannot support my own escape commands within the
driver. Therefore the esc-L, esc-S, and esc-U commands do not
function with the older firmware. However, you can get the same
results by using the open-apple key instead of the escape key with
these three commands.
The DELETE key on the Apple //e and //c generates the code $FF when
it is pressed. This code is interpreted as a backspace, the same as
the left arrow ($08).
2. STB-80 Driver:
The STB-80 was one of the best 80-column cards on the market. STB
Systems no longer makes it though, because they have opted for the
IBM marketplace. I have one, and so do many of you, so I wrote a
driver for it.
When you load the assembler with the STB-80 driver, it automatically
switches to 80-column mode. It is not possible to switch back to
40-column mode in the assembler. To leave the assembler, type the FP
command and then hit RESET or ctrl-RESET.
If you wish to do some printing, turn on your printer with the
PR#slot command. The cursor will remain active on the screen, but
you will see no characters as you type. The printer will remain
connected until you use the NEW command, finish an assembly, or get a
syntax error in a command line. To dis-connect on purpose without
assembling or erasing your source program, purposely generate a
syntax error by typing "X" and a RETURN.
- 3 -
---------------------------------------------------------------------
3. Videx Driver:
The Videx card that I have is version 2.4, with the softswitch. The
firmware is such that to offer the same features you are used to in
the S-C 40-column version I have to directly call two internal
firmware routines, and to directly program the cursor generator on
the Videx board. This means that my driver may not work with your
Videx card, if your card has different firmware at these two
addresses. It also means that my Videx driver will almost certainly
not function with so-called "Videx-compatible" cards.
The two internal routines are CHRGET (at $C39B in version 2.4) and
NTSHFT (at $C870 in version 2.4). If you find the corresponding
routines in your Videx firmware, you should be able to substitute the
addresses in my driver and reassemble it. If you need assistance,
call us. (ver 2.3: CHRGET $C38D (90?) NTSHFT $C86E)
Printer operation and leaving the assembler are the same as with the
STB-80 card. Of course, if you have no "soft switch" with your Videx
card, you will need to re-enter 80-column mode to get any display
after leaving the assembler.
4. Writing your own driver:
You may customize the existing drivers, or write your own. All of
the source code for my three drivers is on the release disk,
well-commented. Follow the same outline, and you will succeed.
Assemble two versions, one with LOCATION .EQ $1000 and the other with
LOCATION .EQ $D000.
Remember that the driver should be no longer than 244 bytes
($3700-37F3 and $F700-F7F3). The last 12 bytes in the driver page
are reserved for use by the Laumer Research Full Screen Editor. Of
course, if you are quite sure you will never use the Full Screen
Editor, then you could use these additional 12 bytes in your driver.
If you have any questions about drivers, call us at (214) 324-2050.
When you finish one for another 80-column carci or perhaps an Apple
clone, you might consider sending it to us for others who might have
the same needs.
Enhancements at the Editor Level
1. Shorthand Features:
Previous versions of the S-C Macro Assembler supported three
"shorthand" features: ctrl-E as a handy synonym for "EDIT", esc-L in
column 1 to trace over a file name and automatically LOAD it from
disk, and esc-L after a line number to generate a star-dash line.
- 4 -
---------------------------------------------------------------------
Version 2.0 continues to support those, and adds three more.
Ctrl-C in column 1 will spell out "CATALOG" and wait for you to type
RETURN, or append slot and drive data and then type RETURN.
Esc-S in column 1 is an Automatic-SAVE command. It depends for
operation on your cooperation: you must place a special comment line
somewhere near the beginning of your source program (as one of the
first ten lines). This comment line has the form:
1000 *HHHHHHSAVE filename
The "H" characters are actually ctrl-H characters, which you type in
by a series of six ctrl-O,ctrl-H pairs. As you are typing they will
appear in inverse on the acreen. If you LIST the line, the ctrl-H
characters will make the "SAVE filename" part print over the top of
the line number, so all you will see is:
SAVE filename
When you type esc-S, the first ten lines will be scanned looking for
a comment line with a letter S following the "*" (any arbitrary
characters may separate the "*" and "S"). If such a line is found,
it will be listed on the screen. Then the line as it appears on the
screen will be picked up and placed in the input buffer, and the
cursor placed at the end of the line. You may then type RETURN to
SAVE the file. Or you may append slot and drive data and then type
RETURN. Or you my type ctrl-X to abort the command.
2. Enhancements to the COPY Command:
We have slightly modified the way the COPY command works. In prior
versions a range of lines copied retained the original line numbers,
even though that meant you had out of sequence numbers in memory.
The new version generates a series of new line numbers for the copied
lines. The new copy of the lines will all have the same line number
as the target line of the COPY command. For example, COPY
1200,1240,1520 would copy lines 1200-1240 just before line 1520, and
assign all the new lines the number 1520.
The new version also allows the option of deleting the original
lines, turning COPY into a move command. After the lines are copied,
the question "DELETE ORIGINAL?" is asked; a "Y" response will cause the
original lines to be deleted. Any other response will cause the
original lines to remain.
After a COPY operation is complete, you should RENUMBER the source
lines. However, it need not be done immediately. There are cases
when it is advantageous to postpone the RENUMBERing a short while.
- 5 -
---------------------------------------------------------------------
For example, suppose I want to copy three separate blocks so that
they end up one after the other, all before a given spot in the
source code...
:COPY 3000,3150,4900
DELETE ORIGINAL? Y
:COPY 2700,2720,4900
DELETE ORIGINAL? Y
:COPY 6750,7040,4900
DELETE ORIGINAL? Y
:REN
3. Case Toggle
If you are using the 40-column version, or either Videx or STB-80
versions, you can turn the upper-case lock off and on by typing
ctrl-S. On the //e or //c, use the case lock button on the keyboard.
4. Linkage to the Full Screen Editor:
We have simplified the linkage to the Launer Research Full Screen
Editor. We built in a trap for the "/" command character which
switches you over to the FSE, so that the patch code which must be
loaded at the end of page $F7 is much shorter. The last 12 bytes
only of that page are now used for the patch, from $F7F4-$F7FF. (The
lower 244 bytes of that page are used for the I/O driver.)
Two files are included on our release disk which when EXECed will
load in the FSE and patch the assembler for its use: "LOADER FSE"
and "LOADER FSE & ASM".
5. New User Vectors:
We added several new user vectors for your own enhancements. These
are in addition to the PRT and USR commands already included in
previous versions.
In case you would like to add another escape command, we left an
opening in the table. Esc-U (or open-apple-U on //e) vectors to a
JMP instruction at $D00C. Change the jump address so that it jumps
to your own escape handler code, and you will gain control anytime
esc-U is typed during line input. Terminate your escape handler code
with an RTS opcode. When you get control, the line as it has been
typed so far is in the buffer starting at $200, and the number of
characters so far is in the X-register.
We also added a single character command similar to the "&" in
Applesoft. If you type a "." as the first character of a command
line, then when you type the RETURN key control will branch to a
vector at $D00F. The instruction at $D00F is a JMP instruction.
Insert your own address into that instruction, and you can decode the
entire line in whatever manner you wish.
Because of the addition of these vectors, some other vectors and
customization data items have moved. Here is the latest table of
vectors and parameters:
- 6 -
---------------------------------------------------------------------
$1000 $D000
Based Based Description Contents
----- ----- ------------------ ---------
$1000 $D000 Hard Entry JMP HARD.INIT
$1003 $D003 Soft Entry JMP SOFT
$1006 $D006 USR Vector JMP SOFT
$1009 $D009 PRT Vector JMP SOFT
$100C $D00C Esc-U Vector JMP RDL.ERR
$100F $D00F "." Vector JMP SOFT
$1012 $D012 Object Vector JMP STORE.OBJECT.BYTE
$1015 $D015 .US Vector JMP COMMENT
$1018 $D018 Tab Character .DA #$89 (Ctrl-I)
$1019 $D019 Tab Settings .DA #14,#18,#27,#32,#0
$101E $D01E Esc-L Char .AS -/-/ (star-dash)
$101F $D01F Compression Limit .DA #4
$1020 $D020 Wild Card Char .DA #$17 (Ctrl-W)
$1021 $D021 Char Out JMP MON.COUT ($FDED)
$1024 $D024 Low Men Unprotect .DA $0000
$1026 $D026 High Men Unprotect .DA $0000
$1028 $D028 LDA # Opcode .HS A9
$1029 $D029 Starting page for symbol table ($38 or $10)
6. New Insert Character for EDIT:
When editing a line with the EDIT command, the in8ert mode is now
invoked by ctrl-A (mnemonic for ADD), rather than ctrl-I. This was
done because the TAB key on the //e and //c produces a ctrl-I code.
We wanted TAB to mean tab! The TAB or ctrl-I keys now perform a
clear-to-tab function when operating under the EDIT command.
Skip-to-tab is still invoked by ctrl-T.
7. Full 5-digit Line Numbers:
Line numbers may now have up to five digits, in the range from 0
through 65535. Versions prior to 1.1 restricted line numbers to the
range 0-9999. If the numbers are less than 10000, they will print as
four-digit numbers with leading zeroes if necessary. Larger numbers,
of course, will print as five-digit numbers.
8. Improved HIDE Operation:
The HIDE command now performs an automatic MERGE before hiding the
current section of source code. This allows a string of LOAD
filenamel, HIDE, LOAD filename 2, HIDE, .. MERGE commands to merge a
lot of source files together.
9. To make room for all these enhancements, cassette tape LOAD and
SAVE commands have now been removed. We bet hardly a soul will miss
them!
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Enhancements at the Assembler Level
1. .OP Directive:
The .OP directive is used to enable the assembly of a particular
instruction set. I suppose "OP" could stand for either "Opcodes" or
"Option". The normal default case is the instruction set of the
plain unadorned 6502.
If you wish to assemble Sweet-16 opcodes, you now need to tell the
assembler so in advance by a line like:
1000 .OP SW16
This has the advantage of catching those cases in which a typing
error such as BM1 instead of BMI is made. In previous versions of
the assembler, the Sweet-16 BM1 opcode would be assembled, with no
error message, even though you expected the 6502 BMI opcode. In
version 2.0 you would not have enabled Sweet-16 assembly, so the
typing error would be caught.
Here are all the possible values which may be used with the Op
directive:
OP 6502
OP SWl6
OP 65C02
OP 65R02
OP 65802
OP 65816
The .OP processor actually only scans for several key characters. If
none of them are found, the 6502 mode is set. If "S" is found,
Sweet-16 mode is set. If "C" is found, the normal 65C02 mode is set.
If "R" is found, the Rockwell extended 65C02 mode is set. If "8" is
found, the 65802/65816 mode is set.
Two aliases are included in the opcode table, by popular demand.
"BGE" is an alias for "BCS", since "BCS" is often used to mean
"Branch if Greater than or Equal". Likewise, "BLT" is and alias for
"BCC", meaning "Branch if Less Than
All of the modes include as a subset the standard 6502 opcodes and
addressing modes. The following tables indicate which opcodes and
addressing modes are added with each .OP selection.
- 8 -
---------------------------------------------------------------------
65C02 Mode -- adds the following new opcodes with the addressing
modes shown:
BRA reladdr Branch Always
PHX Push X-register
PHY Push Y-register
PLX Pull X-register
PLY Pull Y-register
STZ zp Store Zero
STZ zp,X Store Zero
STZ abs Store Zero
STZ abs,X store Zero
TRB zp Test and Reset Bits
TSB zp Test and Set Bits
The 65C02 mode also adds the following addresaing modes to 6502
opcodes:
BIT #val8 Test Bits
BIT zp,X Test Bits
BIT abs,X Test Bits
INC Increment A-register
DEC Decrement A-register
JMP (abs,X) Jump indexed indirect
ADC (zp) Direct Indirect mode
(also for AND, CMP, EOR, LDA, ORA, SBC, and STA)
65R02 Mode -- includes all of the 65C02 opcodes and aadressing modes,
and adds four more opcodes:
SMB bit,zp
RMB bit,zp
BBR bit,zp,reladdr
BBS bit,zp,reladdr
These actually use up 32 opcode values, because the bit 1 (0-7)
becomes part of the opcode byte.
Abbreviations: reladdr...8-bit relative address
zp........8-bit address in page zero
abs.......16-bit address
val8......8-bit immediate value
bit.......3-bit bit number, 0-7
- 9 -
---------------------------------------------------------------------
658()2/65816 Mode -- includes all of the 65C02 opcodes and addressing
modes, and adds the following new opcodes with the addressing modes
shown:
PEA val16 Push 16-bit value on stack
PEI val8 Push 8-bit value on stack
PER longreladdr Push 16-bit relative address
BRL longreladdr Branch Always, 16-bit reladdr
JML (abs) Jump Long Absolute Indirect
JSL longabs Jump Long Absolute
RTL Long Return from Subroutine
MVP Xongabs,longabs Block Move Up
MVN longabs,longabs Block Move Down
PHB Push Data Bank Register
PLB Pull Data Bank Register
PHD Push D-register
PLD Pull D-register
PHK Push Program Bank Register
REP #valB Reset Status Bits
SEP Ival8 Set Status Bits
TCD Transfer C to D
TDC Transfer D to C
TCS Transfer C to S
TSC Transfer S to C
TXY Transfer X to Y
TYX Transfer Y to X
XBA Exchange B and A
XCE Exchange Carry-bit with Emulation-Bit
COP Co-Processor Interrupt
STP Stop Clock until RESET
WAI Stop Clock until Ready plus NMI or IRQ
WDN No-operation, reserved for future systems
Abbreviations: val8..........8-bit immediate value
val16.........16-bit immediate value
longreladdr...16-bit relative address
abs...........16-bit address
longabs.......24-bit address
- 10 -
---------------------------------------------------------------------
The 65802/65816 mode also adds the following new addressing modes to
6502 opcodes:
To the ADC, AND, CNP, EOR, LDA, ORA, SBC1 and STA opcodes, four new modes:
ADC val8,S Stack Relative
ADC (val8,S),Y Stack Relative Indirect Indexed
ADC >(zp) Direct Indirect Long
ADC >(zp),Y Indirect Indexed Long
To the ADC, AND, CNP, EOR, LDA, ORA, and SBC opcodes, a new 16-bit
immediate mode. This is not a true mode, because the opcodes values
are the same as the 8-bit immediate opcodes. At execution time a
P-register bit determines whether one or two bytes of data will be
used. The syntax in the S-C Macro Assembler for 8- or 16-bit
immediate operands is as follows:
8-bit Immediate
LDA #expr low 8-bits
LDA /expr mid 8-bits of 24-bits
LDA ^expr high 8-bits of 24-bits
16-bit Immediate
LDA ##expr low 16-bits
LDA //expr mid 16-bits of 32-bits
LDA ^^expr high 16-bits of 32-bits
We decided to use the double-delimiter to indicate 16-bit immediate
values so that it would be reaciily apparent upon reading your
assembly source code what you intended. An alternative we considered
was to use a new directive to tell the assembler whether to assemble
8- or 16-bit immediate values. We thought that would lead to more
programming bugs as the simple reading of a source line would not
indicate which mode was being used.
Note that you really only need the # and ## modes, because you can
get the others by dividing the expression by 256 one or more times.
JMP longabs Jump with 24-bit address
JSR (abs,X) Jump to Subroutine Indexed Indirect
(Strictly speaking, the 65802 level probably should not allow the long
addressing modes. However, Version 2.0 makes no distinction between
65802 and 65816 at this time.)
Abbreviations: val8......8-bit immediate value
zp........8-bit address
expr......32-bit expression
abs.......16-bit address
longabs...24-bit address
- 11 -
---------------------------------------------------------------------
2. Expressions:
In previous versions of the S-C assemblers the operand expressions
were limited to 16-bits. Since the 65816 uses a 24-bit address bus,
this is no longer adequate. We decided to change to 32-bit
expressions, even though 24 might have been enough. Up to 24 bits
are meaningful in 65816 instructions, and up to 32 bits are
meaningful in .DA directives.
The .DA directive already allowed you to generate either 8-bit or
16-bit data values. We have now added the capability of generating
24-bit and 32-bit values, using this syntax:
.DA #expr 8-bits (low-order byte)
.DA /expr 8-bits (next-to-lowest byte)
.DA expr 16-bits (low-order 16 bits)
.DA expr/256 16-bits (middle 16 bits of 32)
.DA expr/65536 16-bits (high-order 16 bits)
.DA <expr 24-bits (low-order 24 bits)
.DA <expr/256 24-bits (high-order 24 bits)
.DA >expr 32-bits
In all the multiple byte cases, the bytes will be stored lowest-byte
first; this is the normal 6502 way.
Of course, you may put more than one value on a single .DA line,
connected by commas, and you may mix sizes on the line.
1010 *-----------------------------------
0800- 78 1020 BYTE .DA #$12345678 LOW BYTE
0801- 56 1030 .DA /$12345678 2ND BYTE
0802- 56 1040 .DA #$12345678/256 2ND BYTE
0803- 34 1050 .DA #$12345678/65536 3RD BYTE
0804- 12 1060 .DA /$12345678/65536 4TH BYTE
0805- 12 1070 .DA #$12345678/65536/256 4TH BYTE
1080 *-----------------------------------
0806- 78 56 1090 WORDl6 .DA $12345678 LOW
0808- 56 34 1100 .DA $12345678/256 MIDDLE
080A- 34 12 1110 .DA $12345678/65536 HIGH
1120 *-----------------------------------
080C- 78 56 34 1130 W0RD24 .DA <$12345678 LOW
080F- 56 34 12 1140 .DA <$12345678/256 HIGH
1150 *-----------------------------------
0812- 78 56 34
0815- 12 1160 WORD32 .DA >$12345678
1170 *-----------------------------------
0816- 11 33 22
0819- 66 55 44
081C- AA 99 88
081F- 77 1180 .DA #$11,$2233,<$445566,>$778899AA
1190 *-----------------------------------
- 12 -
---------------------------------------------------------------------
We also added three operators to those you may use in operand
expressions. Boolean operations of logical product (AND), or (OR),
and exclusive-or (EOR) are now available. Use the following operator
characters:
AND -- &
OR -- ! or |
EOR -- ^
Here are some examples:
$12345678 & $F0F0F0F0 is $10305070
$12345678 | $F0F0F0F0 is $F2F4F6F8
$l2345678 ^ $F0F0F0F0 is $E2C4A688
Binary constants are now supported. The syntax is "%11000011101" (up
to 32 bits). To make it easier to read the binary constants, you may
include optional periods as visual separators between the binary
digits or groups of digits. Here are some examples:
0800- AD 08 01 1000 LDA %1.0000.1000
0803- 29 7F 1010 AND #%01111111
0805- 01 80 1020 .DA %1000000000000001
0807- 34 12 1030 .DA %0001.0010.0010.0100
ASCII literals with the high-bit set are now allowed, and are
signified with the quotation mark. Note that a trailing quotation
mark is optional, just as is a trailing apostrophe with the
low-bit-zero ASCII literals.
0600- A9 58 1000 LDA #'X
0802- A9 D8 1010 LDA #"X
0804- C1 42 E3 1020 .DA #"A",#'B',#"c"
3. Force zero page, absolute, or long modes~
The 6502 assembly language has several ambiguous modes. For example,
1000 VALUE .EQ $05
1010 LDA VALUE
could be assembled in two different ways, both perfectly valid. Since
VALUE is in page zero, "A5 05" is one possisle way to assemble it.
However, "AD 05 00" is also perfectly valid. The assembler normally
decides which mode it can use. In this case the assembler would use
the zero page form, "A5 05". If you want to force the assembler to
use the longer form, you could do so by putting the .EQ line later in
the program. That works, but it is not a desirable technique.
Borrowing syntax from some other assemblers, I have added the
capability to force the mode you desire. If you write a ">"
character before the operand, the long mode will be forced. You can
also use "<" to force the zero page mode. If you are writing code
which will be assembled to execute inside page zero, you may find
cases in which you need the "<" capability.
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Big Mac, Merlin, and some other assemblers share this syntax. For
some reason Apple's ToolKit uses the ">" and "<" in exactly the
opposite sense.
The long mode may be forced by prefixing ">>" to the operand. Here
are some examples:
1000 OP 65816
1010 *------------------------------
000800- A5 03 1030 LDA 3
000802- AD 03 00 1040 LDA >3
000805- AF 03 00 00 1050 LDA >>3
000809- 4C 03 00 1060 JMP 3
00080C- 5C 03 00 00 1070 JMP >>3
000810- AD 34 12 1080 LDA $1234
000813- A5 34 1090 LDA <$1234
000815- AF 56 34 12 1100 LDA $123456
000819- AD 34 12 1110 LDA >$123456
00081C- 5C 56 34 12 1120 JMP $123456
000820- 4C 34 12 1130 JMP >$123456
4. .BS with Fill Byte:
In previous versions of the assembler, the .BS directive wrote zeroes
on the target file. If object code was stored directly in RAM, no
fill value at all was stored. In the new version, zeroes will be
stored in RAM. For example, ".BS 5". is equivalent to
".HS 0000000000".
We have also added an optional parameter so that you can specify what
the fill byte will be. Here are the syntax and some examples:
.BS count,value
1000 SYMBOL .BS 4,$A0 4-byte variable, filled with $A0 bytes
1010 VALUE .BS 2,$FF 2-byte variable, filled with $FF bytes
1020 BUFFEF .BS 32 32-byte variable, filled with $00 bytes
A RANGE ERROR will be generated if the number of bytes is negative,
or greater than 32767.
5. Object Code Emission Vector:
A new user vector has been added which allows you to gain control
over each byte of the object code as it is emitted from pass two of
the assembler. Ordinarily the object code would be either stored at
the target address in RAM or written on the target file. With this
vector you may write a program to do other things with the object
code. For example, one customer uses this vector to funnel code
through a serial port to another computer. The vector is at $1012 or
$D012, depending on where you have loaded the assembler. It
consists normally of "JMP STORE.OBJECT.BYTE"; put your own address
into the instruction, and you have total control.
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6. Optional Separators in .HS Directive:
The .HS directive now allows optional "." characters before and
after each pair of hex digits. This makes it easier to count the
bytes, and to align the bytes with comments on the lines above or
below the .HS lines.
7. Deeper .DO Nests:
.DO -- .FIN sections can now be nested to 63 levels, rather than the
limit of 8 established in Version 1.0.
8. Additonal Comment Character:
Comment lines may begin with either "*" or ";". This increases
compatiblity with other brands of assemblers. Some people prefer
"*", some prefer ";". Believe it or not, some even use both!
9. Expanded and Flexible Memory Protection:
Memory protection during assembly has been expanded. The assembler
now protects the ranges $001F-$02FF and $03D0-$07FF as well as the
symbol tables, the assembler itself, and DOS.
New user parameters have been added to allow you to selectively
override memory protection. You enter the first and last address of
any range you want to UN-protect in these two parameters. The
beginning address of the range goes at $1024 and $1025, low byte
first ($D024 and $D025 in the high memory version). The end address
of the un-protected range goes at $1026-$1027 ($D026-$D027)
10. SE Directive
The .SE directive has been added, to allow re-definable symbols.
Symbols which are originally defined by the .SE directive may be
re-defined within the same assembly by additional .SE lines. This
directive allows a counter within macro definitions, as shown in the
file "EXAMPLE: .SE DIRECTIVE".
Labels defined with a EQ directive, or by simply appearing in the
label field, cannot be re-defined.
11. Assembly of Separate Phases:
The .PH and .EP directives are now available, to start and end a
phase. With these directives you can assemble a section of code that
is intended to be moved and exectued somewhere else, without having
to create a separate Target File. .PH <expr> effectively sets the
origin to <expr>, but keeps the target address unchanged. When the
.EP directive is encountered, the origin is reset to match the target
address.
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0800- AD 03 9D 1000 START LDA DATA
0803- 60 1010 RTS
1020 *-----------------------------
1030 .PH $9D00
9D00- A9 08 1040 PATCH LDA /ADDR
9D02- 60 1050 RTS
9D03- 1060 DATA .BS 1
1070 .EP
1080 *-----------------------------
0808- 00 9D 1090 ADDR .DA PATCH
SYMBOL TABLE
0808- ADDR 9D03- DATA 9D00- PATCH 0800- START
Notice that the object code column and the symbol table show in
different locations1 but if you examine all the code together,
starting at $0800 and running through $0809:
$800.809
0800- AD 03 9D 60 A9 08 60 00
0808- 00 9D
12. Dummy Sections:
We added .DUMMY and .ED directives to start and end a dummy section.
A dummy section assembles, but no object code bytes are produced.
Dummy sections are useful when specifying data blocks, or when you
want to run as assembly for syntax checking without generating code.
.DUMMY and .ED are equivalent to the OSECT and DEND directives in
Apple's ToolKit Assembler, with the exception that the dummy origin
is not automatically set to $0000. Any .OR directives within a dummy
section will only be effective that section; .DUMMY saves the current
origin, and .ED restores it.
0800- 34 12 1000 ADDR .DA LABEL
1010 *-----------------------------
1020 DUMMY
1030 OR $1234
1234- AD 00 08 1040 LABEL LDA ADDR
1237- 1050 NEXT .BS 1
1238- 1060 AGAIN .BS 1
1070 .ED
1080 *-----------------------------
0802- AD 35 12 1090 LDA NEXT
If you include a .TF directive inside a dummy section, an amazing and
useful thing happens; the assembly listing is written out to the
target file! Be careful with the surprising feature. If you have
several .TF lines in a source program, and some are in dummy
sections, you may get some rather umpredictable results.
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13. Change to Relative-Branch Expressions:
We changed the way the relative branches are assembled, so that "*"
in expressions is equal to the location of the opcode byte.
In Macro 1.0 and earlier versions, "*" equaled the address of the
offset byte, which was non-standard. However, even with this
correction, we do not recommend that you use "*+anything" or
"*-anything" address expressions in relative branches: it is a
dangerous practice that almost always leads eventually to bugs. Use
local labels instead.
14. Additional Option on LIST Directive:
.LIST CON allows you to include those lines that are skipped over by a
.DO -- .FIN section in the assembly listing.
.LIST CON Show excluded lines
.LIST COFF Omit excluded lines
Here is an example:
1000 .LIST CON
1010 .DO 0 (FALSE)
1020 NOP (LISTED, BUT NOT ASSEMBLED)
1030 .ELSE
0800- EA 1040 NOP (LISTED AND ASSEMBLED)
1050 .FIN
Without the .LIST CON, line 1020 would be omitted from the listing.
The default condition is .LIST COFF.
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Brief History of S-C Assembler Versions
We have been working on the S-C Assemblers for over six years now,
and it is interesting to see the progress we have made.
Apr 78 Began working on assembler
various pre-releases (first manual only 1 pagel)
Aug 78 Original tape version, $25
4-char labels
$1000-$1BFF
Jul 79 Disk Version 3.2, $35.
Jul 80 Disk Version 4.0, $55.
Source code $95, first sold Oct 81
Paul Schlyter showed us how to move it to language card RAM.
Don Taylor and Rip Toren showed us how to use the Videx card.
Feb 82 Macro 1.0, $80.
Apr 83 Macro 1.1, $92.50
Source code $100, first sold Apr 84
Nov 83 Macro 1.2 (un-official pre-release)
Nov 84 Macro 2.0, $100
65C02 and 65816 assembly
$1000-$37FF or $D000-$F7FF
Related products
Oct 80 Started "Apple Assembly Line"
Nov 80 Rak-Ware, Deciajon Systems, and Lee Meador disassemblers
Mar 81 Rak-Ware DISASM version 2.0
Apr 81 Rak-Ware XREF for S-C 4.0
May 81 Rak-Ware utilities for 4.0
Jan 83 Attempted to produce Apple /// version, but did not ever finish
the project.
Mar 83 Laumer Research Full Screen Editor
May 83 S-C XREF
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Cross Assemblers
Nov 80 6800 (4.0) Bob S-C
Oct 81 6809 (4.0) Chris Wiggs
Jun 82 6800 (Macro) Bob S-C
Jun 82 6809 (Macro) Bobby Deen
Jul 82 Z-80 (Macro) Bobby Deen
Sep 82 68000 (Macro) Bobby Deen
Dec 82 65C02 (Macro) Bob S-C
Dec 82 8048 (Macro) Bobby Deen
Jan 83 6805 (Macro) Bobby Deem
Mar 83 8051 (Macro) Bobby Deem
Mar 83 1802 (Macro) Bobby Deen
May 83 PDP11 (Macro) Bobby Deen
Jun 83 8085 (Macro) Bobby Deen
Nov 83 6301 (Macro) Bob S-C
Mar 84 Z-8 (Macro) Bobby Deen
Aug 84 1650 (Macro) Bob S-C
Aug 84 1670 (Macro) Bob S-C
Version 4.0 was translated into Japanese by the friendly folk at ESD
Laboratories in Tokyo. They published the Japanese version under
license agreement for several years.
Minimum Assembler, with "The Fourth Leg of the Apple", published by
Dr. Ray Brinker. Dr. Brinker's book/disk introduces the reader to
assembly language, Forth, and other fascinating subjects. Plus, you
get a working (albeit somewhat stripped-down) assembler, a working
Forth, arid other useful stuff. All for $50.
Synassembler, on Atari 400/800, converted from our Version 4.0 by
Steve Hales and published for several years by Synapse. Now "out of
print", as Synapse decided the market was too small.
An unofficial, bootleg copy turned up in the International Apple Core
disk-of-the-month series during 1983. This was a slightly modified
copy of my original tape version, which found its way from Texas to
California by way of Florida and Ontario (Canada).
F-S Macro Assembler, converted from our Macro 1.0 version by Y.
Lempereur at FunSoft Inc, and distributed by Stanton Products, 3710
Pacific Ave., Venice, CA 90291 for $50. Phone (213) 821-2425.
Operates on any Atari with 48K RAM and a disk drive. Jeff Stanton is
selling these to readers of his latest book, "Atari Graphics and
Arcade Games".
Mainstay MacASM, also written by Y. Lempereur at FunSoft, on the
model of the S-C Macro Assembler, to operate in the Macintosh. This
is a full 68000 assembler, for $100 to $150. Available from S-C
Software for $100 while supplies last.
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