Apple-2-SW/beneath-apple-dos
1
0
Fork 0
mirror of https://github.com/iKarith/beneath-apple-dos.git synced 2024-06-08 01:29:43 +00:00
Code Issues Projects Releases Wiki Activity
5988223c94
beneath-apple-dos/D1S1/CH6.1#064000.txt

359 lines
11 KiB
Plaintext
Raw Normal View History

Dump all the documents to text files with markup Looks like CH4 is somewhat hosed, a small amount of bit rot? Doesn't look like too much actually.
2017-07-20 21:50:14 +00:00
.bp
.np
.ce
CHAPTER 6 - USING DOS FROM ASSEMBLY LANGUAGE
.sp1
CAVEAT
Remove trailing nulls, .pp tags PIEWriter dot codes are case-insensitive, and I've deciphered that .pp is a paragraph break. Replace those with blank lines. The NUL at EOF was escaped, but it can be simply deleted. Did so.
2017-07-20 22:08:22 +00:00
Dump all the documents to text files with markup Looks like CH4 is somewhat hosed, a small amount of bit rot? Doesn't look like too much actually.
2017-07-20 21:50:14 +00:00
This chapter is aimed at the advanced
assembly language programmer who
wishes to access the disk without
resorting to the PRINT statement
scheme used with BASIC.
Accordingly, the
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
Remove trailing nulls, .pp tags PIEWriter dot codes are case-insensitive, and I've deciphered that .pp is a paragraph break. Replace those with blank lines. The NUL at EOF was escaped, but it can be simply deleted. Did so.
2017-07-20 22:08:22 +00:00
Dump all the documents to text files with markup Looks like CH4 is somewhat hosed, a small amount of bit rot? Doesn't look like too much actually.
2017-07-20 21:50:14 +00:00
It is often desirable or necessary to
access the Apple's disk drives
directly from assembly language,
without the use of DOS. This is
done using a section of 16 addresses
that are latched toggles, interfacing
directly to the hardware. There are
eight two byte toggles that essentially
represent pulling a TTL line high or
low. Applications which could use
direct disk access range from a
Remove trailing whitespace, normalize dot commands
2017-07-20 22:45:47 +00:00
user written operating system to DOS-independent
Dump all the documents to text files with markup Looks like CH4 is somewhat hosed, a small amount of bit rot? Doesn't look like too much actually.
2017-07-20 21:50:14 +00:00
utility programs. The
device address assignments are given
in Figure 6.1.
.sp
.nf
ADDRESS LABEL DESCRIPTION
---------------------------------------------------------------
$C080 PHASEOFF Stepper motor phase 0 off.
$C081 PHASEON Stepper motor phase 0 on.
$C082 PHASE1OFF Stepper motor phase 1 off.
$C083 PHASE1ON Stepper motor phase 1 on.
$C084 PHASE2OFF Stepper motor phase 2 off.
$C085 PHASE2ON Stepper motor phase 2 on.
$C086 PHASE3OFF Stepper motor phase 3 off.
$C087 PHASE3ON Stepper motor phase 3 on.
$C088 MOTOROFF Turn motor off.
$C089 MOTORON Turn motor on.
$C08A DRV0EN Engage drive 1.
$C08B DRV1EN Engage drive 2.
$C08C Q6L Strobe Data Latch for I/O.
$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
Remove trailing whitespace, normalize dot commands
2017-07-20 22:45:47 +00:00
multiplying the slot number by 16.
Dump all the documents to text files with markup Looks like CH4 is somewhat hosed, a small amount of bit rot? Doesn't look like too much actually.
2017-07-20 21:50:14 +00:00
In hexadecimal this works out nicely
and we can add the value $s0 (where s
is the slot number) to the base
address. If we wanted to engage disk
drive number 1 in slot number 6, for
example, we would add $60 to $C08A
(device address assignment for
engaging drive 1) for a result of
$C0EA. However, since it is
generally desirable to write code
that is not slot dependent, one would
normally use $C08A,X (where the
X register contains the value $s0).
Remove trailing nulls, .pp tags PIEWriter dot codes are case-insensitive, and I've deciphered that .pp is a paragraph break. Replace those with blank lines. The NUL at EOF was escaped, but it can be simply deleted. Did so.
2017-07-20 22:08:22 +00:00
Dump all the documents to text files with markup Looks like CH4 is somewhat hosed, a small amount of bit rot? Doesn't look like too much actually.
2017-07-20 21:50:14 +00:00
In general, the above addresses need
only be accessed with any valid 6502
instruction. However, in the case of
reading and writing bytes, care must
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)
Remove trailing nulls, .pp tags PIEWriter dot codes are case-insensitive, and I've deciphered that .pp is a paragraph break. Replace those with blank lines. The NUL at EOF was escaped, but it can be simply deleted. Did so.
2017-07-20 22:08:22 +00:00
Dump all the documents to text files with markup Looks like CH4 is somewhat hosed, a small amount of bit rot? Doesn't look like too much actually.
2017-07-20 21:50:14 +00:00
Below are typical examples
demonstrating the use of the device
address assignments. For more
examples, see APPENDIX A. Slot 6 is
assumed and the X-register contains
$60.
.sp1
STEPPER PHASE OFF/ON:
Remove trailing nulls, .pp tags PIEWriter dot codes are case-insensitive, and I've deciphered that .pp is a paragraph break. Replace those with blank lines. The NUL at EOF was escaped, but it can be simply deleted. Did so.
2017-07-20 22:08:22 +00:00
Dump all the documents to text files with markup Looks like CH4 is somewhat hosed, a small amount of bit rot? Doesn't look like too much actually.
2017-07-20 21:50:14 +00:00
Basically, each of the four phases
(0-3) must be turned on and then off
again. Done in ascending order, this
moves the arm inward. In descending
Remove trailing whitespace, normalize dot commands
2017-07-20 22:45:47 +00:00
order, this moves the arm outward.
Dump all the documents to text files with markup Looks like CH4 is somewhat hosed, a small amount of bit rot? Doesn't look like too much actually.
2017-07-20 21:50:14 +00:00
The timing between accesses to these
locations is critical, making this a
non-trivial exercise. It is
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.
Remove trailing whitespace, normalize dot commands
2017-07-20 22:45:47 +00:00
.sp1
Dump all the documents to text files with markup Looks like CH4 is somewhat hosed, a small amount of bit rot? Doesn't look like too much actually.
2017-07-20 21:50:14 +00:00
LDA $C089,X Turn motor on.
Remove trailing whitespace, normalize dot commands
2017-07-20 22:45:47 +00:00
.sp1
.fi
Dump all the documents to text files with markup Looks like CH4 is somewhat hosed, a small amount of bit rot? Doesn't look like too much actually.
2017-07-20 21:50:14 +00:00
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:
Remove trailing whitespace, normalize dot commands
2017-07-20 22:45:47 +00:00
.sp1
Dump all the documents to text files with markup Looks like CH4 is somewhat hosed, a small amount of bit rot? Doesn't look like too much actually.
2017-07-20 21:50:14 +00:00
LDA $C08A,X Engage drive 1.
.sp1
LDA $C08B,X Engage drive 2.
.sp1
READ A BYTE:
Remove trailing whitespace, normalize dot commands
2017-07-20 22:45:47 +00:00
.sp1
Dump all the documents to text files with markup Looks like CH4 is somewhat hosed, a small amount of bit rot? Doesn't look like too much actually.
2017-07-20 21:50:14 +00:00
READ LDA $C08C,X
BPL READ
Remove trailing whitespace, normalize dot commands
2017-07-20 22:45:47 +00:00
.sp1
.fi
Dump all the documents to text files with markup Looks like CH4 is somewhat hosed, a small amount of bit rot? Doesn't look like too much actually.
2017-07-20 21:50:14 +00:00
NOTE: $C08E,X must already have been
accessed to assure Read mode. The
loop is necessary to assure that the
Remove trailing whitespace, normalize dot commands
2017-07-20 22:45:47 +00:00
accumulator will contain valid data.
Dump all the documents to text files with markup Looks like CH4 is somewhat hosed, a small amount of bit rot? Doesn't look like too much actually.
2017-07-20 21:50:14 +00:00
If the data latch does not yet
contain valid data the high bit will
be zero.
.sp1
.nf
SENSE WRITE PROTECT:
Remove trailing whitespace, normalize dot commands
2017-07-20 22:45:47 +00:00
.sp1
Dump all the documents to text files with markup Looks like CH4 is somewhat hosed, a small amount of bit rot? Doesn't look like too much actually.
2017-07-20 21:50:14 +00:00
LDA $C08D,X
LDA $C08E,X Sense write protect.
BMI ERROR If high bit set, protected.
.sp1
WRITE LOAD AND WRITE A BYTE
Remove trailing whitespace, normalize dot commands
2017-07-20 22:45:47 +00:00
.sp1
Dump all the documents to text files with markup Looks like CH4 is somewhat hosed, a small amount of bit rot? Doesn't look like too much actually.
2017-07-20 21:50:14 +00:00
LDA DATA
STA $C08D,X Write load.
ORA $C08C,X Write byte.
.sp1
Remove trailing whitespace, normalize dot commands
2017-07-20 22:45:47 +00:00
.fi
Dump all the documents to text files with markup Looks like CH4 is somewhat hosed, a small amount of bit rot? Doesn't look like too much actually.
2017-07-20 21:50:14 +00:00
NOTE: $C08F,X must already have been
accessed to insure Write mode and a
100 microsecond delay should be
invoked before writing.
Remove trailing nulls, .pp tags PIEWriter dot codes are case-insensitive, and I've deciphered that .pp is a paragraph break. Replace those with blank lines. The NUL at EOF was escaped, but it can be simply deleted. Did so.
2017-07-20 22:08:22 +00:00
Dump all the documents to text files with markup Looks like CH4 is somewhat hosed, a small amount of bit rot? Doesn't look like too much actually.
2017-07-20 21:50:14 +00:00
Due to hardware constraints, data
bytes must be written in 32 cycle
loops. Below is an example for an
immediate load of the accumulator,
followed by a write. Timing is so
critical that different routines may
be necessary, depending on how the
data is to be accessed, and code can
not cross memory page boundaries
without an adjustment.
.bp
.nf
LDA #$D5 (3 cycles)
JSR WRITE9 (6)
LDA #$AA (3)
JSR WRITE9 (6)
.
.
.
WRITE9 CLC (2)
WRITE7 PHA (3)
PLA (4)
WRITE STA $C08D,X (5)
ORA $C08C,X (4)
RTS (6)
Remove trailing whitespace, normalize dot commands
2017-07-20 22:45:47 +00:00
.sp2
Dump all the documents to text files with markup Looks like CH4 is somewhat hosed, a small amount of bit rot? Doesn't look like too much actually.
2017-07-20 21:50:14 +00:00
CALLING READ/WRITE TRACK/SECTOR (RWTS)
Remove trailing nulls, .pp tags PIEWriter dot codes are case-insensitive, and I've deciphered that .pp is a paragraph break. Replace those with blank lines. The NUL at EOF was escaped, but it can be simply deleted. Did so.
2017-07-20 22:08:22 +00:00
Dump all the documents to text files with markup Looks like CH4 is somewhat hosed, a small amount of bit rot? Doesn't look like too much actually.
2017-07-20 21:50:14 +00:00
Read/Write Track/Sector (RWTS) exists
in every version of DOS as a
collection of subroutines, occupying
roughly the top third of the DOS
program. The interface to RWTS is
standardized and thoroughly documented by Apple
and may be called by a
Remove trailing whitespace, normalize dot commands
2017-07-20 22:45:47 +00:00
program running outside of DOS.
Remove trailing nulls, .pp tags PIEWriter dot codes are case-insensitive, and I've deciphered that .pp is a paragraph break. Replace those with blank lines. The NUL at EOF was escaped, but it can be simply deleted. Did so.
2017-07-20 22:08:22 +00:00
Dump all the documents to text files with markup Looks like CH4 is somewhat hosed, a small amount of bit rot? Doesn't look like too much actually.
2017-07-20 21:50:14 +00:00
There are two subroutines which must
be called or whose function must be
performed.
Remove trailing nulls, .pp tags PIEWriter dot codes are case-insensitive, and I've deciphered that .pp is a paragraph break. Replace those with blank lines. The NUL at EOF was escaped, but it can be simply deleted. Did so.
2017-07-20 22:08:22 +00:00
Dump all the documents to text files with markup Looks like CH4 is somewhat hosed, a small amount of bit rot? Doesn't look like too much actually.
2017-07-20 21:50:14 +00:00
JSR $3E3 - When this subroutine is
called, the Y and A registers are
loaded with the address of the
Input/Output control Block (IOB) used
by DOS when accessing RWTS. The low
order part of the address is in Y and
the high order part in A. This
subroutine should be called to locate
the IOB and the results may be stored
in two zero page locations to allow
storing values in the IOB and
retrieving output values after a call
to RWTS. Of course, you may set up
your own IOB as long as the Y and A
registers point to your IOB upon
calling RWTS.
Remove trailing nulls, .pp tags PIEWriter dot codes are case-insensitive, and I've deciphered that .pp is a paragraph break. Replace those with blank lines. The NUL at EOF was escaped, but it can be simply deleted. Did so.
2017-07-20 22:08:22 +00:00
Dump all the documents to text files with markup Looks like CH4 is somewhat hosed, a small amount of bit rot? Doesn't look like too much actually.
2017-07-20 21:50:14 +00:00
JSR $3D9 - This is the main entry to
the RWTS routine. Prior to making
this call, the Y and A registers must
be loaded with the address of an IOB
describing the operation to be
performed. This may be done by first
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
Remove trailing whitespace, normalize dot commands
2017-07-20 22:45:47 +00:00
.sp1
Dump all the documents to text files with markup Looks like CH4 is somewhat hosed, a small amount of bit rot? Doesn't look like too much actually.
2017-07-20 21:50:14 +00:00
BYTE DESCRIPTION
00 Table type, must be $01
01 Slot number times 16 (s0: s=slot. Example: $60)
02 Drive number ($01 or $02)
03 Volume number expected ($00 matches any volume)
04 Track number ($00 through $22)
05 Sector number ($00 through $0F)
06-07 Address (LO/HI) of the Device Characteristics Table
08-09 Address (LO/HI) of the 256 byte buffer for
READ/WRITE
0A Not used
0B Byte count for partial sector ($00 for 256 bytes)
0C Command code $00 = SEEK
$01 = READ
$02 = WRITE
$04 = FORMAT
0D Return code - The processor CARRY flag is set upon
return from RWTS if there is a
non-zero return code:
$00 = No errors
$08 = Error during initialization
$10 = Write protect error
$20 = Volume mismatch error
$40 = Drive error
$80 = Read error (obsolete)
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
Remove trailing whitespace, normalize dot commands
2017-07-20 22:45:47 +00:00
.sp1
Dump all the documents to text files with markup Looks like CH4 is somewhat hosed, a small amount of bit rot? Doesn't look like too much actually.
2017-07-20 21:50:14 +00:00
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
Remove trailing whitespace, normalize dot commands
2017-07-20 22:45:47 +00:00
.sp1
Dump all the documents to text files with markup Looks like CH4 is somewhat hosed, a small amount of bit rot? Doesn't look like too much actually.
2017-07-20 21:50:14 +00:00
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)
04 - Track number ($00 through $22)
06/07 - Pointer to the DCT
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
Remove trailing whitespace, normalize dot commands
2017-07-20 22:45:47 +00:00
10 - Current Drive number
Dump all the documents to text files with markup Looks like CH4 is somewhat hosed, a small amount of bit rot? Doesn't look like too much actually.
2017-07-20 21:50:14 +00:00
.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)
03 - Volume number ($00 matches any volume)
04 - Track number ($00 through $22)
05 - Sector number ($00 through $0F)
06/07 - Pointer to the DCT
08/09 - Pointer to 256 byte user data buffer
0B - Byte count per sector ($00)
0C - Command code for READ ($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
Remove trailing whitespace, normalize dot commands
2017-07-20 22:45:47 +00:00
10 - Current Drive number
Dump all the documents to text files with markup Looks like CH4 is somewhat hosed, a small amount of bit rot? Doesn't look like too much actually.
2017-07-20 21:50:14 +00:00
.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)
03 - Volume number ($00 matches any volume)
04 - Track number ($00 through $22)
05 - Sector number ($00 through $0F)
06/07 - Pointer to the DCT
08/09 - Pointer to 256 byte user data buffer
0B - Byte count per sector ($00)
0C - Command code for WRITE ($02)
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
Remove trailing whitespace, normalize dot commands
2017-07-20 22:45:47 +00:00
10 - Current Drive number
Dump all the documents to text files with markup Looks like CH4 is somewhat hosed, a small amount of bit rot? Doesn't look like too much actually.
2017-07-20 21:50:14 +00:00
.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)
03 - Volume number ($00 will default to 254)
06/07 - Pointer to the DCT
0C - Command code for FORMAT ($04)
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
Remove trailing whitespace, normalize dot commands
2017-07-20 22:45:47 +00:00
10 - Current Drive number
Dump all the documents to text files with markup Looks like CH4 is somewhat hosed, a small amount of bit rot? Doesn't look like too much actually.
2017-07-20 21:50:14 +00:00
.bp
.nx ch6.2
Reference in New Issue Copy Permalink