The ASCOP4 assembler supports the COP400 series of 4-bit microprocessors. The COP400 family provides a wide choice of RAM, ROM, and IO capability. The ascop4 assembler specific directives configure the assembler to support a large number of COP400 family processors.
PROCESSOR SPECIFIC DIRECTIVES
.cop Directive
Format:
.cop 'type'
The COP400 family of processors have instruction set and ROM
memory differences which are configured by specifying the .cop
directive followed by the processor type.
A .cop directive without an argument initializes the assem-
bler to accept all instructions, sets the ROM size to 2K, en-
ables full functionality of the xad instruction, and sets the
.__.CPU. variable to zero.
The .cop directive currently supports the following processor
types where [n] is the value given to the assembler .__.CPU.
variable:
402 [1] 404 [2] 404M [3]
410 [4] 410L [5] 410C [6]
411 [7] 411L [8] 411C [9]
413 [10] 413C [11] 413CH [12]
420 [13] 420L [14]
421 [15] 421L [16]
422 [17] 422L [18]
424 [19] 424L [20]
425 [21] 425L [22]
426 [23] 426L [24]
440 [25] 441 [26] 442 [27]
2440 [28] 2441 [29] 2442 [30]
444 [31] 444L [32]
445 [33] 445L [34]
The variable '.__.CPU.' is by default defined as local and
will not be output to the created .rel file. The assembler com-
mand line options -g or -a will not cause the local symbols to
be output to the created .rel file.
The assembler .globl directive may be used to change the
variable type to global causing its definition to be output to
the rel file. The inclusion of the definition of the variable
'.__.CPU.' might be a useful means of validating that separately
assembled files have been compiled for the same processor type.
The linker will report an error for variables with multiple non
equal definitions.
.rom_size Directives
Format:
.rom256 256 Byte ROM Size
.rom512 512 Byte ROM Size
.rom1k 1024 Byte ROM Size
.rom2k 2048 Byte ROM Size
.xad Directive
Format:
.xad n
The .xad directive can override the operating mode of the xad
instruction selected by a .cop directive. A non zero value of n
limits the xad instruction to the following form:
xad 3,15
and a zero or blank argument restores the xad instruction to
its full functionality.
.setpg Directive
Format:
.setpg [base [,area]]
The .setpg directive is used to inform the assembler of the
area containing ROM pages 2 and 3 and the offset address within
the selected area. The only value allowed for the offset is
0x80 (the beginning of page 2).
The normal invocation methods are:
.area ROM
.setpg
or
.setpg 0x80,ROM
for the COP4 microprocessors. If a .setpg directive is not
issued the assembler defaults the region to the area "_CODE" at
offset 0x80.
The need for this directive will become apparent from the
following short description of the jp and jsrp instructions.
The jp and jsrp instructions are unique in the sense that
they are dependent upon where in the program space they are
located. This can be seen by comparing the opcode values for jp
and jsrp.
jp loc
- 0x80 | <A6:A0> Jump within pages 2 and 3
- 0xC0 | <A5:A0> Jump within current page, not 2 or 3
jsrp sub
- 0x80 | <A5:A0> JSR to page 2, not in 2 or 3
--------------------------------------------------------
jp 0xE0
- 0x80 | <A6:A0> -->> 0x80 | 0x60 -->> 0xE0
- (jp to page 3, jp in page 2 or 3)
jp 0x20
- 0xC0 | <A5:A0> -->> 0xC0 | 0x20 -->> 0xE0
- (jp to current page, page 0)
or
jp 0xA0
- 0x80 | <A6:A0> -->> 0x80 | 0x20 -->> 0xA0
- (jp to page 2, jp in page 2 or 3)
jsrp 0xA0
- 0x80 | <A5:A0> -->> 0x80 | 0x20 -->> 0xA0
- (jsrp to page 2)
The assembler and linker are not capable of changing the op-
code based upon the relocated address of the instruction. Thus
a new instruction mnemonic, jp23, is introduced to indicate a jp
instruction within pages 2 and 3. The linker verifies that any
jp23 jump address is in this region (0x80 to 0xFF).
jp Use in pages 0, 1, and >= 4
jp23 Use in pages 2 and 3
The programmer is required to manually verify that jp23 is
used in pages 2 and 3 and that jp is used in all other pages.
The COP400 documentation resolves the jp - jsrp conflict by
not allowing a jsrp instruction to be located within page 2 or
3. The programmer must manually verify that a jsrp instruction
is not located in page 2 or 3. Use the jsr instruction in pages
2 and 3.
COP400 INSTRUCTION SET
Instruction Argument Syntax:
A 4-Bit Accumulator
B 7-Bit RAM Address Register
Br Upper 3-Bits of B (Register Address)
Bd Lower 4-Bits of B (Digit Address)
C 1-Bit Carry Register
d 4-Bit Operand Field (RAM Digit Select)
r 3-Bit Operand Field (RAM Register Select)
n 2-Bit Operand Data (Immediate)
y 4-Bit Operand Data (Immediate)
addr jump address or label
The terms n, y, d, r and addr may be expressions.
Note that not all addressing modes may be valid with every
instruction. Refer to the COP400 technical data for valid
modes.
The following tables list the mnemonics and arguments recog-
nized by the ASCOP4 assembler.
COP400 Instructions
Arithmetic Instructions
asc (Add RAM to A with carry, then SKC)
add (Add RAM to A)
adt (Add ten to A)
aisc #y (Add immediate, Skip on carry)
casc (Add RAM to /A with carry, then SKC)
comp (Ones complement of A to A)
nop (No Operation)
or (OR RAM with A)
rc (Reset Carry)
sc (Set Carry)
xor (Exclusive-OR RAM with A)
Transfer Of Control Instructions
jid (Jump Indirect)
jmp addr (Jump)
jp addr (Jump within Page)
jp23 addr (Jump to Page 2 or 3)
jsrp addr (Jump to Subroutine Page 2)
jsr addr (Jump to Subroutine)
ret (Return from Subroutine)
retsk (Return from Subroutine then Skip)
halt (Halt)
it (Idle until Timer overflow)
Memory Reference Instructions
came (Copy A,RAM to E)
camq (Copy A,RAM to Q)
camt (Copy A,RAM to T)
cema (Copy E to A,RAM)
cqma (Copy Q to A,RAM)
ctma (Copy T to A,RAM)
ld r (Load RAM into A, XOR Br with r)
ldd r,d (Load RAM into A from Direct r,d)
lqid (Load Q Indirect)
rmb n (Reset RAM Bit)
smb n (Set RAM Bit)
stii #y (Store Immediate to RAM, Increment Bd)
x r (RAM <--> A, Br XOR r)
xad r,d (RAM(r,d) <--> A)
xds r (RAM <--> A, Bd - 1 -> Bd, Br XOR r)
(Skip on Decrement of Bd from 0 to 15)
xis r (RAM <--> A, Bd + 1 -> Bd, Br XOR r)
(Skip on Increment of Bd from 15 to 0)
Register Reference Instructions
cab (Copy A to Bd)
cba (Copy Bd to A)
lbi r,d (Load B from Direct r,d)
lei #y (Load EN from Immediate data)
xabr (A <--> Br)
xan (A <--> N, N is 2-Bit Stack Pointer)
Test Instructions
skc (Skip if C is True)
ske (Skip if A Equals RAM)
skgz (Skip if G is Zero)
skgbz #n (Skip if G Bit is Zero)
skmbz #n (Skip if RAM Bit is Zero)
Input/Output Instructions
camr (Output A,RAM to R Port)
ing (Input G Port into A)
inh (Input H Port into A)
inin (Input IN Inputs into A)
inil (Input IL Latches into A)
inl (Input L Port into RAM,A)
inr (Input R Port init RAM,A)
obd (Output Bd to D Outputs)
ogi #y (Output Immediate to G Port)
omg (Output RAM to G Ports)
omh (Output RAM to H Port)
xas (Exchange A with SIO)
ASCOP4 MACRO FILE The 'ascop4.mac' macro file contains an alternate method to configure the ascop4 assembler for a specific processor. The macro file contains macros which redefine the instructions present in the full ascop4 functionality. This file can be mod- ified to specify processors not natively supported by the ascop4 assembler. See the internals of the macro file for implementa- tion details.
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