User Commands - Commodore 1551 User Manual

130 PRINT#15,"B-E";2;0;1;8
140 CLOSE 2
150 CLOSE 15
160 END
USER COMMANDS
Load Track I, Sector 8 in it & execute
Tidy up after
Most User commands are intended to be used as machine language JMP or Basic
SYS commands to machine language programs that reside inside the disk memory.
However, some ofthem have other uses as well. The User! and User2 commands are used
to replace the Block-Read and Block-Write commands,
UI
re-starts the 1551 without
changing its variables, UJ cold-starts the 1551 almost as if it had been turned off and on
again.
User Command
ul or ua
u2 or ub
u3 or uc
u4 or ud
uS or ue
u6 or uf
u7 or ug
u8
or
uh.
u9 or ui
u:
or
uj
Function
block read replacement
block write replacement
jump to $0500
jump to $0503
jump to $0506
jump to $0509
jump to $050c
jump to $050f
jump to ($fffa) reset tables
power up vector
By loading these memory locations with another machine language JMP command,
such as JMP $0520, you can create longer routines that operate in the disk's memory
along with an easy-to-use jump table.
FORMAT FOR USER COMMANDS:
PRINT#15, "Ucharacter"
where "character" defines one of the preset user commands listed above.
EXAMPLES:
PRINT# 15, "U:"
PRINT# 15, "U3"
68
Preferred form of DOS RESET command
Execute program at start of buffer 2