THE STRUCTURE OF VIRTUAL MACHINE
The software represents a virtual 8-bit binary computer with a von Neumann architecture. The instruction set includes 102 instructions.
At the programmer's disposal are a separate 8-bit register as Accumulator (AC) to perform arithmetic and logical operations with its values, RAM.
RAM capacity is 256 bytes.
There is also a set of 8-bit registers in the high addresses of RAM which are set aside for specific uses:
- Stack Pointer SP;
- Flags Register FR;
- Data Input register DI;
- Instruction Pointer IP;
- Data Output register DO.
Registers
Accumulator AC. Designed to perform arithmetic and logical operations with the contents. If in the Debug mode the DO/A/<-- key was pressed, the contents of this register can be shown on the DO0 – DO7 LEDs.
Virtual machine registers are mapped into memory and located in the upper memory space from address 251 to 255.
Stack Pointer SP (memory address 251 (binary 11111011)). The register contains the address value of the top of the stack (TOS).
- A byte is pushed onto the stack by decrementing SP by 1 and writing a byte at the new TOS.
- When a byte is popped off the stack (operation is performed in reverse order). A byte is read from a memory cell addressed by SP, then SP increments by 1.
Flags Register FR (memory address 252 (binary 11111100)). Discrete bits within FR register are as follows:
- ZF - Zero Flag (if = 1, the previous instruction in the Accumulator resulted in a zero answer);
- CF - Carry Flag (if = 1, the previous instruction in the Accumulator resulted in a Carry Flag, otherwise = 0);
- TF - Trap Flag (= 0 if it works in the normal mode. = 1 if overflow of the address counter occurred);
Data Input register DI (memory address 253 (binary 11111101)). DI stores data that ‘old programmers’ entered ‘from toggle switches’. The contents of the register are displayed by LEDs DO0 – DO7.
Instruction Pointer IP (memory address 254 (binary 11111110)). The contents of the register can be written to or read ‘from toggle switches’. The register contains the address of instruction that is currently executing. When the instruction executed the contents of register are automatically changed (by the number of bytes the instruction occupies), indicating the address of the next instruction. The contents of this register are displayed by the LEDs AD0 – AD7.
Data Output register DO (memory address 255 (binary 11111111)). As a rule, the register contains the result or a discreet byte of the calculation. The contents of this register are displayed by the DO0 – DO7 LEDs.
INSTRUCTION SET
Instructions can be a single-byte, a 2-byte, a 3-byte, (also there are three 4-byte instructions). Therefore when instruction executed, to indicate the next instruction the instruction pointer IP will increment by 1, 2, 3 or 4, respectively.
| Processor Control Instructions |
| NOP | 00h | 00000000b | 1 byte |
| No operation (Doesn’t perform any operation, ‘empty’ instruction). |
| SPEED | 02h | 00000010b | 2 bytes |
| Set the speed that the CPU steps through each instruction after starting the program.
2nd byte - speed reduction parameter |
| ADDRIP | 03h | 00000011b | 2 bytes | TF |
| Add the contents of a specific memory sell to the contents of the instruction pointer IP. Store the result in IP.
2nd byte - memory address of value to add to instruction pointer. If the Instruction Pointer IP overflow occurred, then the Trap Flag TF = 1, otherwise TF = 0. |
| HLT | 0Eh | 00001110b | 1 byte |
| Pause executing instructions. The HALT LED lights up red. Pressing the ENTER or the RUN/STOP key will continue the execution with the next instruction. Usually used to wait for a value from the keyboard to be entered into the DI register. |
| STOP | 0Fh | 00001111b | 1 byte |
| Stops program execution until the RUN/STOP key is pressed. |
| Data Transfer to / from Accumulator |
| MOVLA | 10h | 00010000b | 2 bytes | ZF |
| Write a literal value to the Accumulator.
2nd byte - data to write. If result in the Accumulator is 00h, Zero Flag ZF = 1, otherwise ZF = 0. |
| MOVRA | 11h | 00010001b | 2 bytes | ZF |
| Copy a memory cell contents to the Accumulator.
2nd byte - memory address of value to copy. If result in the Accumulator is 00h, Zero Flag ZF = 1, otherwise ZF = 0. |
| MOVAR | 12h | 00010010b | 2 bytes | ZF |
| Copy the Accumulator contents to a specific memory cell.
2nd byte - memory address to write to. If result in the Accumulator is 00h, Zero Flag ZF = 1, otherwise ZF = 0. |
| MOVIRA | 13h | 00010011b | 2 bytes | ZF |
| Copy to Accumulator the contents of a memory location pointed to by the contents of the specified memory cell.
2nd byte - an intermediate location containing an effective address of data. If result in the Accumulator is 00h, Zero Flag ZF = 1, otherwise ZF = 0. |
| MOVIAR | 14h | 00010100b | 2 bytes |
| Copy the contents of Accumulator to a memory location pointed to by the contents of specified memory cell.
2nd byte - an intermediate location containing an effective address of data. |
| MOVILR | 15h | 00010101b | 3 bytes |
| Write a literal value to a memory location pointed to by the contents of specified memory cell.
2nd byte - a literal value to write 3d byte - an intermediate location containing an effective address to write the data. |
| MOVAL | 16h | 00010110b | 2 bytes | ZF |
| Write the contents of Accumulator to the 2nd byte of the instruction itself.
2nd byte - a byte to write to. It can have any initial value that will change during the execution of the instruction. If result in the Accumulator is 00h, Zero Flag ZF = 1, otherwise ZF = 0. |
| LOIRA | 17h | 00010111b | 2 bytes | ZF |
| Write to Accumulator the contents of a memory location pointed to by the contents of the specified memory cell. Increment or decrement by 1 the contents of an intermediate location (an effective address). If CF=0, address increments by 1, if CF=1, address decrements by 1.
2nd byte - an intermediate location containing an effective address of data. If result in the Accumulator is 00h, Zero Flag ZF = 1, otherwise ZF = 0. |
| CLEARA | E4h | 11100100b | 2 bytes | ZF |
| Copy the contents of Accumulator to a specific memory address, then set the Accumulator to zero.
2nd byte - a memory address to write to. Always sets ZF = 1. |
| Data Transfer to Memory |
| MOVLR | 20h | 00100000b | 3 bytes |
| Write a literal value to specified memory address.
2nd byte - data to write. 3rd byte - memory address to write to. |
| MOVRR | 21h | 00100001b | 3 bytes |
| Copy the contents from one memory cell to another.
2nd byte - memory address to read from. 3rd byte - memory address to write to. |
| MOVIRR | 22h | 00100010b | 3 bytes |
| Copy the contents of one memory cell to another with indirect addressing of both memory cells.
2nd byte - an intermediate location containing an effective address to copy from. 3rd byte - an intermediate location containing an effective address to copy to. |
| CLEARR | E5h | 11100101b | 2 bytes |
| Write a zero to a specific memory cell.
2nd byte - a memory address to write to. |
| Exchange Instructions |
| XCHGRA | 30h | 00110000b | 2 bytes | ZF |
| Swaps the contents of the Accumulator and a specific memory cell.
2nd byte - memory address of the contents to swap. If result in the Accumulator is 00h, Zero Flag ZF = 1, otherwise ZF = 0. |
| XCHGRR | 31h | 00110001b | 3 bytes |
| Swaps the contents between a pair of memory cells.
2nd byte - memory address of contents to swap. 3rd byte - memory address of contents to swap. |
| Arithmetic and Logical Instructions (Accumulator) |
| ADDLA | 40h | 01000000b | 2 bytes | ZF, CF |
| Add a literal value to the contents of the Accumulator. Result stored in the Accumulator.
2nd byte - the value to add. If result in the Accumulator is 00h, Zero Flag ZF = 1, otherwise ZF = 0. If result in the Accumulator is overflow (a value exceeds FFh), Carry Flag CF = 1, otherwise СF = 0. |
| ADDRA | 41h | 01000001b | 2 bytes | ZF, CF |
| Add a value from specific memory cell to the contents of the Accumulator and store the result in the Accumulator.
2nd byte - memory address to add value from. If result in the Accumulator is 00h, Zero Flag ZF = 1, otherwise ZF = 0. If result in the Accumulator is overflow (a value exceeds FFh), Carry Flag CF = 1, otherwise СF = 0. |
| SUBLA | 42h | 01000010b | 2 bytes | ZF, CF |
| Subtract a literal value from the contents of the Accumulator and store the result in the Accumulator.
2nd byte - a value to subtract. If result in the Accumulator is 00h, Zero Flag ZF = 1, otherwise ZF = 0. If result in the Accumulator is a negative number, the Carry Flag CF = 1, otherwise CF = 0. |
| SUBRA | 43h | 01000011b | 2 bytes | ZF, CF |
| Subtract the contents of a specific memory cell from the Accumulator, store the result in the Accumulator. If result is a negative number, it is represented with a sign bit in the Carry Flag CF.
2nd byte - memory address of value to subtract. If result in the Accumulator is 00h, Zero Flag ZF = 1, otherwise ZF = 0. If result in the Accumulator is a negative number, the Carry Flag CF = 1, otherwise CF = 0. |
| ANDLA | 44h | 01000100b | 2 bytes | ZF |
| Perform a logical AND of the contents of the Accumulator and a literal value. Store the result in the Accumulator.
2 bytes - a value to ‘AND’ with Accumulator. If result in the Accumulator is 00h, Zero Flag ZF = 1, otherwise ZF = 0. If result in the Accumulator is overflow (a value exceeds FFh), Carry Flag CF = 1, otherwise СF = 0. |
| ANDRA | 45h | 01000101b | 2 bytes | ZF |
| Perform a logical ‘AND’ of the contents of the Accumulator and the contents of specific memory sell. Store the result in the Accumulator.
2nd byte - memory address of value to ‘AND’. If result in the Accumulator is 00h, Zero Flag ZF = 1, otherwise ZF = 0. If result in the Accumulator is overflow (a value exceeds FFh), Carry Flag CF = 1, otherwise СF = 0. |
| ORLA | 46h | 01000110b | 2 bytes | ZF |
| Perform a logical ‘OR’ of the contents of the Accumulator and a literal value.
2nd byte - a value to ‘OR’ with the Accumulator. If result in the Accumulator is 00h, Zero Flag ZF = 1, otherwise ZF = 0. |
| ORRA | 47h | 01000111b | 2 bytes | ZF |
| Perform a logical ‘OR’ of the contents of the Accumulator and the contents of a specific memory cell.
2nd byte - memory address within value to ‘OR’. If result in the Accumulator is 00h, Zero Flag ZF = 1, otherwise ZF = 0. |
| XORLA | 48h | 01001000b | 2 bytes | ZF |
| Perform a logical ‘XOR’ of the contents of the Accumulator and a literal value. Store the result in the Accumulator.
2nd byte - a value to ‘XOR’ with the Accumulator. If result in the Accumulator is 00h, Zero Flag ZF = 1, otherwise ZF = 0. |
| XORRA | 49h | 01001001b | 2 bytes | ZF |
| Perform a logical ‘XOR’ the contents of the Accumulator and a value within specific memory cell. Store the result in the Accumulator.
2nd byte - memory address of value to ‘XOR’. If result in the Accumulator is 00h, Zero Flag ZF = 1, otherwise ZF = 0. |
| DECA | 4Ah | 01001010b | 1 byte | ZF, CF |
| Decrement the value in the Accumulator by 1.
If result in the Accumulator is 00h, Zero Flag ZF = 1, otherwise ZF = 0. If result in the Accumulator is a negative number, the Carry Flag CF = 1, otherwise CF = 0. |
| INCA | 4Bh | 01001011b | 1 byte | ZF, CF |
| Increment the value in the Accumulator by 1.
If result in the Accumulator is 00h, Zero Flag ZF = 1, otherwise ZF = 0. If result in the Accumulator is a negative number, the Carry Flag CF = 1, otherwise CF = 0. |
| DAA | 4Ch | 01001100b | 1 byte | ZF, CF |
| Decimal correction of the Accumulator after adding binary decimal numbers.
If result in the Accumulator is 00h, Zero Flag ZF = 1, otherwise ZF = 0. If result in the Accumulator is a negative number, the Carry Flag CF = 1, otherwise CF = 0. |
| DAS | 4Dh | 01001101b | 1 byte | ZF, CF |
| Decimal correction of the Accumulator after subtracting binary decimal numbers.
If result in the Accumulator is 00h, Zero Flag ZF = 1, otherwise ZF = 0. If result in the Accumulator is a negative number, the Carry Flag CF = 1, otherwise CF = 0. |
| NOTA | 4Eh | 01001110b | 1 byte | ZF |
| Inversion of the contents of the Accumulator.
If result in the Accumulator is 00h, Zero Flag ZF = 1, otherwise ZF = 0. |
| AAD | 3Eh | 00111110b | 1 bytes | ZF |
| Convert a number in the Accumulator from binary-decimal to binary.
If result in the Accumulator is 00h, Zero Flag ZF = 1, otherwise ZF = 0. |
| AAA | 3Fh | 00111111b | 1 bytes | ZF, CF |
| Convert a number in the Accumulator from binary to binary-decimal.
If result in the Accumulator is 00h, Zero Flag ZF = 1, otherwise ZF = 0. If result in the Accumulator is overflow (a value exceeds FFh), Carry Flag CF = 1, otherwise СF = 0. |
| ADDLACF | 88h | 10001000b | 2 bytes | ZF, CF |
| Add a literal value and a value of the CF bit to the contents of Accumulator. Store the result in the Accumulator.
2nd byte - a literal value to add If result in the Accumulator is 00h, Zero Flag ZF = 1, otherwise ZF = 0. If result in the Accumulator is overflow (a value exceeds FFh), Carry Flag CF = 1, otherwise СF = 0. |
| ADDRACF | 89h | 10001001b | 2 bytes | ZF, CF |
| Add a value within addressed memory cell and a value of the CF bit to the contents of Accumulator. Store the result in the Accumulator.
2nd byte - memory address to add value from. If result in the Accumulator is 00h, Zero Flag ZF = 1, otherwise ZF = 0. If result in the Accumulator is overflow (a value exceeds FFh), Carry Flag CF = 1, otherwise СF = 0. |
| SUBLACF | 8Ah | 10001010b | 2 bytes | ZF, CF |
| Subtract a literal value and a value of the CF bit from the contents of Accumulator. Store the result in the Accumulator.
2nd byte - a literal value to subtract. If result in the Accumulator is 00h, Zero Flag ZF = 1, otherwise ZF = 0. If result in the Accumulator is a negative number, the Carry Flag CF = 1, otherwise CF = 0. |
| SUBRACF | 8Bh | 10001011b | 2 bytes | ZF, CF |
| Subtract a value within addressed memory cell and a value of the CF bit from the contents of Accumulator. Store the result in the Accumulator.
2nd byte - a memory address of value to subtract. If result in the Accumulator is 00h, Zero Flag ZF = 1, otherwise ZF = 0. If result in the Accumulator is a negative number, the Carry Flag CF = 1, otherwise CF = 0. |
| Arithmetic and Logical Instructions (Memory) |
| DECR | 50h | 01010000b | 2 bytes |
| Decrement a value in a specific memory sell by one.
2nd byte - memory address of value with which to decrement. |
| INCR | 51h | 01010001b | 2 bytes |
| Increment a value in a specific memory sell by one.
2nd byte - memory address of value with which to increment. |
| Accumulator Shift Instructions |
| SHIFTLA | 60h | 01100000b | 1 byte | ZF, CF |
| Shift the contents of the Accumulator left by one. The leftmost bit from the Accumulator goes into Carry Flag CF.
If result in the Accumulator is 00h, Zero Flag ZF = 1, otherwise ZF = 0. |
| SHIFTRA | 61h | 01100001b | 1 byte | ZF, CF |
| Shift the contents of the Accumulator right by one. The rightmost bit from the Accumulator goes into Carry Flag CF.
If result in the Accumulator is 00h, Zero Flag ZF = 1, otherwise ZF = 0. |
| ROLACF | 62h | 01100010b | 1 byte | ZF, CF |
| Shift the contents of the Accumulator left through the Carry Flag. The leftmost bit from the Accumulator goes into Carry Flag. The previous value from the Carry Flag writes to the low bit.
If result in the Accumulator is 00h, Zero Flag ZF = 1, otherwise ZF = 0. |
| RORACF | 63h | 01100011b | 1 byte | ZF, CF |
| Shift the contents of the Accumulator right through the Carry Flag. The rightmost bit from the Accumulator goes into Carry Flag. The previous value from the Carry Flag writes to the low bit.
If result in the Accumulator is 00h, Zero Flag ZF = 1, otherwise ZF = 0. |
| Memory Shift Instructions |
| SHIFTLR | 70h | 01110000b | 2 bytes |
| Shift the data within memory cell left by one. The leftmost bit from the memory cell is lost.
2nd byte - memory address of data to shift. |
| SHIFTRR | 71h | 01110001b | 2 bytes |
| Shift the data within memory cell right by one. The rightmost bit from the memory cell is lost.
2nd byte - memory address of data to shift. |
| Bit Manipulation Instructions (Accumulator and Flags) |
| CBA | 80h | 10000000b | 2 bytes | ZF |
| Set a specific bit in the Accumulator to 0.
2nd byte - number of a bit within Accumulator to reset. If result in the Accumulator is 00h, Zero Flag ZF = 1, otherwise ZF = 0. |
| SBA | 81h | 10000001b | 2 bytes |
| Set specific bit in the Accumulator to 1.
2nd byte - number of a bit within Accumulator to set. |
| XCHGAA | 82h | 10000010b | 1 byte | ZF |
| Swap the high and low half-bytes within the Accumulator.
If result in the Accumulator is 00h, Zero Flag ZF = 1, otherwise ZF = 0. |
| CLRCF | 83h | 10000011b | 1 byte |
| Resets the Carry Flag to 0. |
| CLRTF | 84h | 10000100b | 1 byte |
| Resets the Trap Flag TF to 0. |
| MOVCFA | 86h | 10000110b | 2 bytes | ZF |
| Copy the contents of the Carry Flag CF to a specific Accumulator bit.
2nd byte - number of a bit within Accumulator to store a value. If result in the Accumulator is 00h, Zero Flag ZF = 1, otherwise ZF = 0. |
| MOVACF | 87h | 10000111b | 2 bytes | ZF, CF |
| Copy the contents of a specific Accumulator bit to the Carry Flag.
2nd byte - number of a bit within Accumulator to copy. If result in the Accumulator is 00h, Zero Flag ZF = 1, otherwise ZF = 0 |
| Memory Bit Manipulation Instructions |
| CBR | 90h | 10010000b | 3 bytes |
| Set a specific bit within the specified memory cell to 0.
2nd byte - specified bit which to reset. 3rd byte - specified memory address of data. |
| SBR | 91h | 10010001b | 3 bytes |
| Set a specific bit within the specified memory cell to 1.
2nd byte - specified bit which to reset. 3rd byte - specified memory address of data. |
| MOVCFR | 92h | 10010010b | 3 bytes |
| Copy the contents of the Carry Flag to a specific bit within a specified memory cell.
2nd byte - specified bit with which to store the value. 3rd byte - specified memory address of data. |
| MOVRCF | 93h | 10010011b | 3 bytes | CF |
| Copy the contents of a specific bit within a specified memory cell to the Carry Flag CF.
2nd byte - specified bit to copy value from. 3rd byte - specified memory address of data. |
| Stack Manipulation Instructions |
| PUSHA | A0h | 10100000b | 1 byte | ZF |
| Write the contents of the Accumulator to the stack
If result in the Accumulator is 00h, Zero Flag ZF = 1, otherwise ZF = 0. |
| PUSHR | A1h | 10100001b | 2 bytes |
| Write the value from a specific memory cell to the stack.
2nd byte - memory address of value to read from. |
| PUSHL | A2h | 10100010b | 2 bytes |
| Write a literal value to the stack.
2nd byte - the value to write. |
| POPA | A3h | 10100011b | 1 byte | ZF |
| Move the contents from the stack to Accumulator AC.
If result in the Accumulator is 00h, Zero Flag ZF = 1, otherwise ZF = 0. |
| POPR | A4h | 10100100b | 2 bytes |
| Move the contents from the stack to a specific memory cell.
2nd byte - memory address to write to. If result in the Accumulator is 00h, Zero Flag ZF = 1, otherwise ZF = 0. |
| MOVSPA | A5h | 10100101b | 1 byte | ZF |
| Write the contents of the Stack Pointer SP to the Accumulator.
If result in the Accumulator is 00h, Zero Flag ZF = 1, otherwise ZF = 0. |
| MOVASP | A6h | 10100110b | 1 byte | ZF |
| Write the contents of the Accumulator to the Stack Pointer SP.
If result in the Accumulator is 00h, Zero Flag ZF = 1, otherwise ZF = 0. |
| SETSP | A7h | 10100111b | 2 bytes |
| Write a byte to the Stack Pointer SP.
2nd byte - data to write. |
| INITSP | A8h | 10101000b | 1 byte |
| Write a fixed initial value of 251 (11111011b) to the Stack Pointer SP. |
| Subroutines Instructions and Unconditional Transfer |
| CALL | B0h | 10110000b | 2 bytes |
| Initialize the execution of a subroutine until RETURN instruction is executed. Then return to the very next memory location after the CALL instruction.
2nd byte - subroutine entry address. |
| RETURN | B1h | 10110001b | 1 byte |
| Return from a subroutine initialized by the CALL instruction. |
| JMP | B2h | 10110010b | 2 bytes |
| Unconditional Transfer. Go to the specific memory address and continue executing instructions from there.
2nd byte - Instruction address to jump to. |
| Conditional Transfer Instructions |
| LOOP | C0h | 11000000b | 3 bytes |
| Conditional transfer with a counter. Decrement the contents of a specific memory cell by one. If the result is non-zero, go to the address specified in the 3rd byte of the instruction. Otherwise execute the next instruction.
2nd byte - memory address within value to decrement. 3rd byte - transition address, if the result is non-zero. |
| LOOPI | C1h | 11000001b | 3 bytes |
| Conditional transfer with a counter. Increment the contents of a specific memory cell by one. If the result is non-zero, go to the address specified in the 3rd byte of the instruction. Otherwise execute the next instruction.
2nd byte - memory address within value to increment. 3rd byte - transition address, if the result is non-zero. |
| JRBNZ | C2h | 11000010b | 4 bytes |
| Check a specific bit within a specified address. If it is ZERO, go to the next instruction. If it = 1, go to the address specified in the 4th byte of the instruction.
2nd byte - bit to check. 3rd byte - specified memory address of a bit. 4th byte - transition address if the bit = 1. |
| JRBZ | C3h | 11000011b | 4 bytes |
| Check a specific bit within a specified address. If it is ONE, go to the next instruction. If it = 0, go to the address specified in the 4th byte of the instruction.
2nd byte - bit to check. 3rd byte - specified memory address. 4th byte - transition address, if the bit = 0. |
| JZFNZ | C4h | 11000100b | 2 bytes |
| Check the Zero Flag. If ZF = 1, go to a specified transition address. If ZF = 0, execute the next instruction.
2nd byte - transition address, if ZF = 1. |
| JZFZ | C5h | 11000101b | 2 bytes |
| Check the Zero Flag. If ZF = 0, go to the specified transition address. If ZF = 1, execute the next instruction.
2nd byte - transition address, if the flag ZF = 0. |
| JCFNZ | C6h | 11000110b | 2 bytes |
| Check the Carry Flag. If CF = 1, go to a specified transition address. If CF = 0, execute the next instruction.
2nd byte - transition address, if the flag CF = 1. |
| JCFZ | C7h | 11000111b | 2 bytes |
| Check the Carry Flag. If CF = 0, go to a specified transition address. If CF = 1, execute the next instruction.
2nd byte - transition address, if the flag CF = 0. |
| JTFNZ | C8h | 11001000b | 2 bytes |
| Check the Trap Flag. If TF = 1, go to a specified transition address. If TF = 0, execute the next instruction.
2nd byte - transition address if the TF flag = 1. |
| JTFZ | C9h | 11001001b | 2 bytes |
| Check the Trap Flag. If TF = 0, go to a specified transition address. If TF = 1, execute the next instruction.
2nd byte - transition address if the TF = 0. |
| JALR | B7h | 10110111b | 3 bytes |
| Compare the contents of Accumulator with the contents of addressed memory cell. If a value within Accumulator is less than a value within addressed memory cell, then go to the address specified in the 3rd byte of the instruction.
2nd byte - a memory address of value to compare. 3nd byte - a memory address to jump to. |
| JALL | B8h | 10111000b | 3 bytes |
| Compare the contents of Accumulator with a literal value. If a value within Accumulator is less than a literal value, then go to the address specified in the 3rd byte of the instruction.
2nd byte - a literal value to compare. 3nd byte - a memory address to jump to. |
| JAER | B9h | 10111001b | 3 bytes |
| Compare the contents of Accumulator with the contents of addressed memory cell. If a value within Accumulator is equal to a value within addressed memory cell, then go to the address specified in the 3rd byte of the instruction.
2nd byte - a memory address of value to compare. 3nd byte - a memory address to jump to. |
| JAEL | BAh | 10111010b | 3 bytes |
| Compare the contents of Accumulator with a literal value. If a value within Accumulator is equal to a literal value, then go to the address specified in the 3rd byte of the instruction.
2nd byte - a memory address of value to compare. 3nd byte - a memory address to jump to. |
| JAGR | BBh | 10111011b | 3 bytes |
| Compare the contents of Accumulator with the contents of addressed memory cell. If a value within Accumulator is greater than a value within addressed memory cell, then go to the address specified in the 3rd byte of the instruction.
2nd byte - a memory address of value to compare. 3nd byte - a memory address to jump to. |
| JAGL | BCh | 10111100b | 3 bytes |
| Compare the contents of Accumulator with a literal value. If a value within Accumulator is greater than a literal value, then go to the address specified in the 3rd byte of the instruction.
2nd byte - a literal value to compare. 3nd byte - a memory address to jump to. |
| JRLR | BDh | 10111101b | 3 bytes |
| Compare the contents of one memory cell with the contents of another memory cell. If a value within the first memory cell is less than a value within the second one, then go to the address specified in the 4th byte of the instruction.
2nd byte - a memory address of the first value to compare. 3nd byte - a memory address of the second value to compare. 4th byte - a memory address to jump to. |
| JRER | BEh | 10111110b | 4 bytes |
| Compare the contents of one memory cell with the contents of another memory cell. If a value within the first memory cell is equal to a value within the second one, then go to the address specified in the 4th byte of the instruction.
2nd byte - a memory address of the first value to compare. 3nd byte - a memory address of the second value to compare. 4th byte - a memory address to jump to. |
| JRGER | BFh | 10111111b | 4 bytes |
| Compare the contents of one memory cell with the contents of another memory cell. If a value within the first memory cell is equal or greater than a value within the second one, then go to the address specified in the 4th byte of the instruction.
2nd byte - a memory address of the first value to compare. 3nd byte - a memory address of the second value to compare. 4th byte - a memory address to jump to. |
| Input / Output Instructions |
| OUTDO | D0h | 11010000b | 1 byte |
| Write a value from the Accumulator to the Data Output register (memory cell 255). |
| INDI | D1h | 11010001b | 1 byte | ZF |
| Write a value from the Data Input register DI (memory cell 253) to the Accumulator.
If result in the Accumulator is 00h, Zero Flag ZF = 1, otherwise ZF = 0. |
| INKBD | D2h | 11010010b | 1 byte | ZF |
| Write a code of the last key pressed to the Accumulator. Pauses program execution, the HALT LED lights up yellow until any key is pressed. Stores key code in the Accumulator.
If result in the Accumulator is 00h, Zero Flag ZF = 1, otherwise ZF = 0. |
| OUTKBD | D3h | 11010011b | 1 byte | ZF |
| Write the contents of the Accumulator to the key color management port. The lower 6 bits determine the address of the key, the higher 2 bits determine the key color.
If result in the Accumulator is 00h, Zero Flag ZF = 1, otherwise ZF = 0. |
| OUTCLRKBD | D4h | 11010100b | 1 bytes |
| Turn off the backlight of all keys (numbers and alphabet), except for the functional keys. |
| INCOLKBD | D5h | 11010101b | 1 bytes |
| Return the key color to the Accumulator. An address of the key is placed in the lower 6 bits of Accumulator before calling the instruction. After the instruction is executed a color code is returned to the higher 2 bits of the Accumulator. |
| Miscellaneous Instructions (Chain Operations and Multiplication) |
| MOVSTR | E0h | 11100000b | 4 bytes | TF |
| Copy the specified number of bytes from the array of memory cells starting from the "source address" to the array of memory cells starting from the "destination address".
2nd byte - the number of cells to copy. 3rd byte - the first memory address in the array to read from. 4th byte - the first memory address in the array to write to. If a resulting value of a memory address goes beyond the address space, then the Trap Flag TF = 1, otherwise TF = 0. |
| MULRA | E1h | 11100001b | 3 bytes | ZF |
| Multiply a value from the Accumulator by a value within a specific memory cell. The third byte specified is a memory address within the low byte of the result stored. The high byte of the result will be stored within the address greater by 1.
2nd byte - memory address of a second factor. 3rd byte - memory address of the low byte of the result to store to. If result in the Accumulator is 00h, Zero Flag ZF = 1, otherwise ZF = 0. |
| DIVRA | E2h | 11100010b | 3 bytes | ZF | СF |
| Divide a value within a specified memory cell by a value in the Accumulator.
2nd byte - memory address of the low byte of the 16-bit dividend. The high byte location follows. 3rd byte - memory address of the low byte of the result. The high byte of the result is stored within address larger by 1. The fractional part (a division remainder) will be stored within address larger by 2. If overflow occurred, the 4th bit of the Flag Register is set to 1. Otherwise = 0. If a result in the Accumulator is 00h, Zero Flag ZF = 1, otherwise ZF = 0. If a result is overflow (a value exceeds FFFFh), Carry Flag CF = 1, otherwise СF = 0. Instead of DIVRA it is recommended to use the MULRA instruction to multiply by the number inverse of the divisor. |
| RETAD | E3h | 11100011b | 2 bytes | TF |
| It is assumed that this instruction is always followed by a two-byte JMP instruction. Memorize the so-called "return address." The instruction "finds out" the location of its own first byte, and adds 4 to it.
2nd byte - a memory address to write a return address to. If a return address is greater than FFh, then the Trap Flag TF = 1, otherwise TF = 0. |
| X | E6h | 11100110b | 2 bytes |
| Execute one instruction at the address specified in the 2nd byte and then continue the program.
2nd byte - a memory address of the first byte of the instruction to be called. Note! When calling a conditional or unconditional jump instructions, as well as itself, the correct operation of these instructions is not guaranteed. |
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