Utility Subroutines; Utility Subroutine Jump Table - Motorola M68HC11EVBU User Manual

3.2.4

Utility Subroutines

Several subroutines exist that are available for performing I/O tasks. A jump table has been set
up in ROM directly before the interrupt vectors. To use these subroutines, execute a jump to
subroutine (JSR) command to the appropriate entry in the jump table. By default, all I/O
performed with these routines are sent to the terminal port. Redirection of the I/O port is
achieved by placing the specified value (0=SCI, 1=ACIA, 2=DUARTA, 3=DUARTB) into RAM
location IODEV. Utility subroutines available to the user are listed in Table 3-1.
Address Routine
$FF7C .WARMST
$FF7F .BPCLR
$FF82 .RPRINT
$FF85 .HEXBIN
$FF88 .BUFFAR
$FF8B .TERMAR
$FF8E .CHGBYT
$FF91 .READBU
$FF94 .INCBUF
$FF97 .DECBUF
$FF9A .WSKIP
$FF9D .CHKABR
$FFA0 .UPCASE
$FFA3 .WCHEK
$FFA6 .DCHEK
M68HC11EVBU/D
Table 3-1. Utility Subroutine Jump Table
Go to ">" prompt point (skip BUFFALO... message).
Clear breakpoint table.
Display user's registers.
Convert ASCII character in A register to 4-bit binary number. Shift binary
number into SHFTREG from the right. SHFTREG is a 2-byte (4 hexadecimal
digits) buffer. If A register is not hexadecimal, location TMP1 is incremented
and SHFTREG is unchanged.
Read 4-digit hexadecimal argument from input buffer to SHFTREG.
Read 4-digit hexadecimal argument from terminal device to SHFTREG.
Write value (if any) from SHFTREG+1 to memory location pointed to by X.
(Operation also applicable to EEPROM locations.)
Read next character from INBUFF.
Increment pointer into input buffer.
Decrement pointer into input buffer.
Read input buffer until non-whitespace character found.
Monitor input for (CTRL)X, (DELETE), or (CTRL)W requests.
If character in accumulator A is lower case alpha, convert to upper case.
Test character in accumulator A and return with Z bit set if character is white
space (space, comma, tab).
Test character in accumulator A and return with Z bit set if character is
delimiter (carriage return or white space).
MONITOR PROGRAM
Description
3-3 3