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Move first half of chapter 6 to root

This commit is contained in:
T. Joseph Carter 2017-07-21 04:02:04 -07:00
parent 5988223c94
commit 25bdb9698c
1 changed files with 42 additions and 56 deletions
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98
D1S1/CH6.1#064000.txt → ch06.txt
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@ -1,8 +1,5 @@
.bp
.np
.ce
CHAPTER 6 - USING DOS FROM ASSEMBLY LANGUAGE
.sp1
CAVEAT
This chapter is aimed at the advanced
@ -15,7 +12,7 @@ topics covered here may be beyond the
comprehension (at least for the
present) of a programmer who has
never used assembly language.
.sp2
DIRECT USE OF DISK DRIVE
It is often desirable or necessary to
@ -33,8 +30,7 @@ user written operating system to DOS-independent
utility programs. The
device address assignments are given
in Figure 6.1.
.sp
.nf
ADDRESS LABEL DESCRIPTION
---------------------------------------------------------------
$C080 PHASEOFF Stepper motor phase 0 off.
@ -53,15 +49,14 @@ ADDRESS LABEL DESCRIPTION
$C08D Q6H Load Data Latch.
$C08E Q7L Prepare latch for input.
$C08F Q7H Prepare latch for output.
.sp1
Q7L followed by Q6L = Read
Q7L followed by Q6H = Sense Write Protect
Q7H followed by Q6L = Write
Q7H followed by Q6H = Load Write Latch
.sp1
*** figure 6.1 ***
.fi
.bp
The addresses are slot dependent and
the offsets are computed by
multiplying the slot number by 16.
@ -87,8 +82,7 @@ be taken to insure that the data will
be in an appropriate register. All
of the following would engage drive
number 1. (Assume slot number 6)
.sp1
.nf
LDA $C0EA
BIT $C08A,X (where X-reg contains $60)
CMP $C08A,X (where X-reg contains $60)
@ -99,7 +93,7 @@ address assignments. For more
examples, see APPENDIX A. Slot 6 is
assumed and the X-register contains
$60.
.sp1
STEPPER PHASE OFF/ON:
Basically, each of the four phases
@ -114,35 +108,31 @@ recommended that the SEEK command in
RWTS be used to move the arm. See
the section on using RWTS immediately
following.
.sp1
MOTOR OFF/ON:
.sp1
.nf
LDA $C088,X Turn motor off.
.sp1
LDA $C089,X Turn motor on.
.sp1
.fi
NOTE: A sufficient delay should be
provided to allow the motor time to
come up to speed. Shugart recommends
one second, but DOS is able to reduce
this delay by watching the read latch
until data starts to change.
.bp
.nf
ENGAGE DRIVE 1/2:
.sp1
LDA $C08A,X Engage drive 1.
.sp1
LDA $C08B,X Engage drive 2.
.sp1
READ A BYTE:
.sp1
READ LDA $C08C,X
BPL READ
.sp1
.fi
NOTE: $C08E,X must already have been
accessed to assure Read mode. The
loop is necessary to assure that the
@ -150,21 +140,19 @@ accumulator will contain valid data.
If the data latch does not yet
contain valid data the high bit will
be zero.
.sp1
.nf
SENSE WRITE PROTECT:
.sp1
LDA $C08D,X
LDA $C08E,X Sense write protect.
BMI ERROR If high bit set, protected.
.sp1
WRITE LOAD AND WRITE A BYTE
.sp1
LDA DATA
STA $C08D,X Write load.
ORA $C08C,X Write byte.
.sp1
.fi
NOTE: $C08F,X must already have been
accessed to insure Write mode and a
100 microsecond delay should be
@ -180,8 +168,7 @@ be necessary, depending on how the
data is to be accessed, and code can
not cross memory page boundaries
without an adjustment.
.bp
.nf
LDA #$D5 (3 cycles)
JSR WRITE9 (6)
LDA #$AA (3)
@ -195,7 +182,7 @@ without an adjustment.
WRITE STA $C08D,X (5)
ORA $C08C,X (4)
RTS (6)
.sp2
CALLING READ/WRITE TRACK/SECTOR (RWTS)
Read/Write Track/Sector (RWTS) exists
@ -238,10 +225,9 @@ calling $3E3 as described above. The
IOB must contain appropriate
information as defined in the list
on the facing page (offsets are given in hexadecimal):
.bp
.nf
INPUT/OUTPUT CONTROL BLOCK - GENERAL FORMAT
.sp1
BYTE DESCRIPTION
00 Table type, must be $01
01 Slot number times 16 (s0: s=slot. Example: $60)
@ -270,18 +256,18 @@ BYTE DESCRIPTION
0E Volume number of last access (must be initialized)
0F Slot number of last access*16 (must be initialized)
10 Drive number of last access (must be initialized)
.sp1
DEVICE CHARACTERISTICS TABLE
.sp1
BYTE DESCRIPTION
00 Device type (should be $00 for DISK II)
01 Phases per track (should be $01 for DISK II)
02-03 Motor on time count (should be $EFD8 for DISK II)
.bp
RWTS IOB BY CALL TYPE
.sp1
SEEK Move disk arm to desired track
.sp1
Input: Byte 00 - Table type ($01)
01 - Slot number * 16 (s0: s=slot)
02 - Drive number ($01 or $02)
@ -290,13 +276,13 @@ Input: Byte 00 - Table type ($01)
0C - Command code for SEEK ($00)
0F - Slot number of last access * 16
10 - Drive number of last access
.sp1
Output: Byte 0D - Return code (See previous definition)
0F - Current Slot number * 16
10 - Current Drive number
.sp1
READ Read a sector into a specified buffer
.sp1
Input: Byte 00 - Table type ($01)
01 - Slot number * 16 (s0: s=slot)
02 - Drive number ($01 or $02)
@ -310,14 +296,14 @@ Input: Byte 00 - Table type ($01)
0E - Volume number of last access
0F - Slot number of last access * 16
10 - Drive number of last access
.sp1
Output: Byte 0D - Return code (See previous definition)
0E - Current Volume number
0F - Current Slot number * 16
10 - Current Drive number
.bp
WRITE Write a sector from a specified buffer
.sp1
Input: Byte 00 - Table type ($01)
01 - Slot number * 16 (s0: s=slot)
02 - Drive number ($01 or $02)
@ -331,15 +317,15 @@ Input: Byte 00 - Table type ($01)
0E - Volume number of last access
0F - Slot number of last access * 16
10 - Drive number of last access
.sp1
Output: Byte 0D - Return code (See previous definition)
0E - Current Volume number
0F - Current Slot number * 16
10 - Current Drive number
.sp1
FORMAT Initialize the diskette (does not put DOS on disk,
create a VTOC/CATALOG, or store HELLO program)
.sp1
Input: Byte 00 - Table type ($01)
01 - Slot number * 16 (s0: s=slot)
02 - Drive number ($01 or $02)
@ -349,10 +335,10 @@ Input: Byte 00 - Table type ($01)
0E - Volume number of last access
0F - Slot number of last access * 16
10 - Drive number of last access
.sp1
Output: Byte 0D - Return code (See previous definition)
0E - Current Volume number
0F - Current Slot number * 16
10 - Current Drive number
.bp
.nx ch6.2