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Diffstat (limited to 'cmpen472hw1_McDonnell/Sources/cmpen472hw1_McDonnell.asm')
| -rw-r--r-- | cmpen472hw1_McDonnell/Sources/cmpen472hw1_McDonnell.asm | 63 |
1 files changed, 63 insertions, 0 deletions
diff --git a/cmpen472hw1_McDonnell/Sources/cmpen472hw1_McDonnell.asm b/cmpen472hw1_McDonnell/Sources/cmpen472hw1_McDonnell.asm new file mode 100644 index 0000000..0d13fd1 --- /dev/null +++ b/cmpen472hw1_McDonnell/Sources/cmpen472hw1_McDonnell.asm @@ -0,0 +1,63 @@ +********************************************************************************************** +* +* Title: Star Fill (In Memory) Homework #1 +* +* Objective: CMPEN472 Homework #1 demonstration program. Fill 225 bytes of memory with '*'. +* +* Revision: V1.0 +* +* Date: Jan. 22, 2025 +* +* Programmer: Jacob McDonnell +* +* Company: The Pennsylvania State Universtiy +* Electrical Engineering and Computer Science +* +* Algorithm: While Loop demo of HCS12 Assembly +* +* Register Use: A accumulator: character to be placed in memory +* B accumulator: counter of filled memory locations +* X register: pointer to memory location to fill +* +* Memory use: RAM locations $3000 to $30E1 +* +* Input: No input, data and parameters are hard coded. +* +* Output: Memory locations $3000 to $30E1 are filled with '*' character. +* +* Observation: This program is designed for instruction purpose. +* This program can be a template for other loop based code. +* +* Comments: This program is developed and simulated using CodeWarrior Development Software. +* +********************************************************************************************** +* Parameter Declaration Section +* +* Export Symbols + xdef pgstart ; export 'pgstart' symbol + absentry pgstart ; for assembly entry point +* Symbols and Macros +porta equ $0000 ; i/o port address +portb equ $0001 +ddra equ $0002 +ddrb equ $0003 +********************************************************************************************** +* Data Section +* + org $3000 ; reserved memory starting address +here ds.b $e1 ; 225 memory locations reserved +count dc.b $e1 ; constant counter for stars = 225 +* +********************************************************************************************** +* Program Section +* + org $3100 ; Program Start Address in RAM +pgstart ldaa #'*' ; Load '*' into accumulator A + ldab count ; Load count of stars into B + ldx #here ; Load address pointer into X +loop staa 0,x ; Put a start at this memory location + inx ; Go to the next memory location + decb ; Decrement the counter + bne loop ; Loop if not done +done bra done ; Task finished + end ; Last line of a file
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