Commodore 1541-II User Manual page 4

PART TWO: GUIDE TO ADVANCED OPERATION AND PROGRAMMING
Chapter 4: Commands •.•••••••••.•..•..••••••••••••••.•••.••••••••••••• 25
Command Channel ••.......••.••••••••••.•••••.•..•••••••••••.. 25
Reading the Error Channel •.•..••.••••••••.•••••••••..••••.•.••• 26
Housekeeping hints ••.•••.••••••.••.•.....••.•••.....••••••..... 28
Saving programs •..•.....••.......•..••••••..•.....•••.....•... 29
Save with replace •••••..••...•••• ,. ....••..•.•..•...•..•....•.•. 30
Verifying programs .....•..••....•..•...•..•...•..•.......•.•.. 30
Erasing programs •...•.......••.••••.•.....•.•••••....•........ 31
Scratch for advanced users •••...•.••••........•....•..•..•..•.•. 33
Renaming programs ••.••••.•......................•.•••.••..... 34
Renaming and scratching troublesome programs .......•.•••.•..... 36
Copying programs •••••....••..•..•...•••..•....•.............• 37
Validating the d. i skette ••..••....•.•••.•...•.....•...•..•••..•..• 38
Initializing •••...•.•....•.•..•....•.•••..•..•...•.•....••.••••• 40
Chapter 5: Sequential Data Files ..•.•••........•.......•••...•..•.••..•.. 42
The concept of files •......•...•..........•..••••.... ., .•••....... 42
Opening a sequential file •.•..•...•.......•.•..•...•.••••••.••... 42
Adding to a sequential file .....•........••••..•.•....••.......•.. 45
Writing file dala: Print# ..••.••.•..•....•••..•...••..•..•..•..•. 46
Closing a file ......••.........••..•...•.........••..•..•....• • . 48
Reading file data using INPUT# .•..•••••.....••••••..•..•....... 49
More about INPUT (advanced) .•••••••.••.....••......•..•...... 50
Numeric Data Storage on Diskette •..•.••••••..••.••.••••••••..•.• 51
Reading File Data: Using GET# ....••.•...••..•..•....•..•...•••. 52
Demonstration of Sequential Files •••••.•.•.....••••••••..•.•••... 54
Chapter 6: Relative Data Files .•.•.....••••...•......•.....•.••.••....... 55
The value of relative access ••..•..•......••.•.......••.•..•.•.••. 55
Files, Records, and Fields .....•..•.............•...•.........•.. 55
File limits •.•••.•........•...•....•...•...•....•...•..•••...... 56
Creating a relative file ..•.•.••......•..••••..........••......... 56
Using relative files: Record# ..........•.•..•.....•...•...•..••••. 57
Completing relative file creation ....•...••.•...••.............•••. 59
Expanding a relative file .•.....•......•••••....••.•••.•....•.... 60
Writing relative file data .••••.....•.•...••.....•...•.••......... 61
Designing a relative record .•..•.•.•........••.•......••....••••• 61
Writing the record ....••••••...•....•........••.•••.....•..•..• 62
Reading a relative record ..•...............•.................... 63
The v!llue of index files .•.•••.• ,. .•..•..••...•.•................•• 64
Chapter 7: Direct Access Commands .••.•••..•••...•....•..•..•.•.. • ...••. 65
A tool for advanced users .••.......•••........•..••••........••. 65
Diskette organization ..•.•......•..•.••••..•....•..•.••...•..... 65
Opening a data channel ••.••.•..••.•..••..••..................•. 65
Block-Read •..••...•...•.••••......•.....••.•.......•....•.... 66
Block-Write •••.•.......•••••....•......•..•••.••.........• . •.. 67
The original commands ....••.•••..........•..•......•..... • .... 68
The buffer pointer ......•......•...•.. . • ..•.........••....•..•.. 69
AllOC:ating blocks •....••...••......•••.••..............•..••.... 70
Freeing blocks •.....•..•..•..•.......•..•..•...•....... • ..••... 71
Using random files (advanced) .•......••••.•.•........•..••..•... 72
Chapter 8: Internal Disk Commands......... . .......................... 73
1541 Memory Map •..••.............•••...........•....•..•.. : : 73
Memory Read •..............•...•..•..•..•••...•......•.....•• 74
Memory Write ..•.•...•••..•••...•.....•...•....•............ .
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Memory Execute •••..•....•...•.••.....•............•..•.....•• 77
Block Execute .•..••..•.•.....•..•...•••..•......•..........•.. 77
User commands .........•.................••....•............•. 78
Chapter 9: Machine Language Programs .................................. 80
Disk-related kernal subroutines ...................•....••........ 80
Appendices
A. Changing the Device Number ....••................••....•.... 81
B. Error Messages .••......••.....•.•..•..•...•...•..•......•.. 83
C. Diskette Formats ....••...••..........•..•...... ....•........ 87
D. Disk Command Quick Reference Chart ••..••....•..•.....••... 92
E. Test/Demo Diskette • • . • . • • . . • . . • . . . • . . • . . . • 93
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List of Figures
1. Front Panel ..•.••..••••..•••..•.•...••.•.••..•..........•... 5
2. Back Panel 6
3. Floppy Disk.
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4. Position for Diskette Insertion ................................. 12