*
*  BOOTSTRAP LOADER FOR HELIOS DISK
*
 COPY DSKPORTS
*
 ORG 0C367H  The location in the BOOTLOAD prom
*
BOOTS MVI A,SD0+NH1+DS1+DS2+DO+NSP
*
*  Load A with: Select left hand drive
*               Select disk 0
*               Load head on 0
*               No step
*               Direction Outward
*               Restore head to track 0
*
 OUT DCOM  Send out Disk Command port
 OUT DTADL  Clear Status
 MVI A,-1  Send a 'do nothing' to transfer latch
 OUT DTCOM
*
BOOTL IN DSTAT  Get Status
 ANI SC  Seek completed to track 0?
 JNZ BOOTL  If not, keep checking
*
 MVI A,SD0+NH1+NRS+DS1+DS2+DO+NSP
*
*  Send same command as before but deactivate Restore
*
 OUT DCOM
*
IFIN IN DSTAT  Check status again
 RLC .  Now we're looking for the index hole
 JC IFIN  Carry means not found
 LXI B,1290H
*
IFIN2 DCX B  Delay until past Header block
 MOV A,B
 ORA C
 JNZ IFIN2
*
IFIN3 IN DSTAT  Check for index hole again
 RLC
 JC IFIN3
*
SWAIT IN DSTAT
 ANI SR  Is status ready?
 JZ SWAIT  Zero = No
*
 XRA A
 OUT DTADL  This is the receiving address in memory
 OUT DTADH  (0000)
*
 LXI H,0340H  This is the number of bytes to transfer
 MOV A,L
 OUT DTLL  Send out low byte
 MOV A,H
 OUT DTLH  Send out high byte
*
 MVI A,NER+RD  Give the read command
 OUT DTCOM
*
DLOOP IN DSTAT
 ANI CC+CE+SR+TC  Check for transfer errors
 JZ DLOOP
 ANI CE  Any CRC errors?
 JNZ BOOTS  If so, start over
 IN DSTAT
 ANI TC+SR  Check for transfer complete
 JZ DLOOP
 RST 0  Looks good, let's go bring up PTDOS
 HLT
*
 END
*