The table below describes the machine instruction set available with TINY. Several symbols are used in the descriptions: ACC = contents of the accumulator, c(x) = contents of memory at address x, PC = value of Program Counter, SP = value of Stack Pointer, c(SP) = contents of memory at the address indicated by the SP register.

Op Code Mnemonic Description

00 STOP STOP execution of TINY program.

(Return control to the Operating System.)

01 LD x LoaD accumulator with contents at the address

specified by operand 'x'.

ACC = c(x)

02 LDI x LoaD (Indirect) accumulator with contents at the

address found in the memory location specified by 'x'.

ACC = c(c(x))

03 LDA x LoaD Address specified by 'x' into accumulator.

ACC = x

04 ST x STore contents of accumulator at address 'x'.

c(x) = ACC

05 STI x STore (Indirect) contents of accumulator at the

address found in the memory location specified by 'x'.

c(c(x)) = ACC

06 ADD x ADD contents at address 'x' to the accumulator.

ACC = ACC + c(x)

07 SUB x SUBtract contents at address 'x' from the accumulator.

ACC = ACC - c(x)

08 MUL x MULtiply contents at address 'x' to the accumulator.

ACC = ACC * c(x)

09 DIV x DIVide contents of accumulator by the contents at 'x'.

ACC = ACC / c(x)

10 IN INput a Character from the keyboard and place the

character's ASCII code into the accumulator.

ACC = ASCII of input character

11 OUT OUTput the Character associated with the ASCII code

found in the accumulator.

12 B x Branch (unconditionally) to address 'x'.

PC = x

13 BP x Branch on Positive accumulator to address 'x'.

PC = x if ACC > 0

14 BN x Branch on Negative accumulator to address 'x'.

PC = x if ACC < 0

15 BZ x Branch on Zero accumulator to address 'x'.

PC = x if ACC = 0

Op Code Mnemonic Description

16 JSB x Jump to SuBroutine whose address is specified by 'x'.

SP = SP - 1

c(SP) = PC

PC = x

17 RSB Return from SuBroutine.

PC = c(SP)

SP = SP + 1

18 PUSH PUSH contents of ACCUM onto stack.

SP = SP - 1

c(SP) = ACC

19 POP POP value off of stack and place in ACCUM.

ACCUM = c(SP)

SP = SP + 1

Pseudo Operations:

DC ‘string’ Define Character string. ASCII codes for characters within single quotation marks

are stored in consecutive addresses.

DB n Define byte. Places value of N in byte at current address. (n must be numeric.)

DS n Define Storage. Reserves next N addresses for future use. (n must be numeric.)

ROM routines:

Address Mnemonic Description

900 PRINTN Converts current integer value in ACC to ASCII characters and outputs the result.

925 PRINTC Outputs ASCII characters contained in memory at the location specified by ACC.

Output continues until a ‘zero-byte’ is detected!

950 INPUTN Execution pauses to accept a numeric value from the user. The input is converted to

decimal format and stored in ACC.

975 INPUTC Execution pauses to accept ASCII text from the user. The input is stored in memory

beginning with the address specified by ACC. A trailing ‘zero-byte’ will be

appended to the end of the ASCII string.