mirror of
https://github.com/iKarith/beneath-apple-dos.git
synced 2024-12-21 15:29:34 +00:00
27bcf5f79c
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.
133 lines
2.8 KiB
Plaintext
133 lines
2.8 KiB
Plaintext
.na
|
|
.fi
|
|
.ll60
|
|
.br
|
|
SECOND PRINTING CORRECTIONS
|
|
.sp3
|
|
3-3
|
|
.sp1
|
|
Data bits are recorded on the
|
|
diskette in precise intervals. For
|
|
the purposes of this discussion, the
|
|
demarcation of these intervals will
|
|
be depicted by a clock bit. Using
|
|
this representation, data written to
|
|
and read back from the diskette takes
|
|
the form shown in Figure 3.2. The
|
|
data pattern shown represents a
|
|
binary value of 101.
|
|
.sp3
|
|
3-10
|
|
.sp1
|
|
at least as long as a typical Gap 3
|
|
(in practice its length is usually
|
|
more than 400 sync bytes, enabling it
|
|
to serve as a Gap 3 type for Address
|
|
Field number 0 (See Figure 3.7 for
|
|
clarity).
|
|
.sp3
|
|
3-17
|
|
.sp1
|
|
page.*
|
|
.sp1
|
|
diagrammed in Figure 3.21.*
|
|
.sp1
|
|
*Figures 3.20 and 3.21 present the
|
|
nibblizing process used by the "6 and
|
|
2" encoding technique. However, the
|
|
concept is the same for the "5 and 3"
|
|
technique.
|
|
.sp3
|
|
4-17
|
|
.sp1
|
|
.nf
|
|
occurred. Either a bad checksum was detected on the data in a
|
|
.fi
|
|
.sp1
|
|
program given there will read any
|
|
track/sector on an unprotected
|
|
diskette into memory, allowing the
|
|
user to examine it or modify the data
|
|
and then, optionally, rewrite it to a
|
|
diskette. Using such a program is
|
|
very important when learning about
|
|
diskette formats and when fixing
|
|
clobbered data.
|
|
.sp3
|
|
5-2
|
|
.sp1
|
|
The file manager, occupying about
|
|
2.8K, is a collection of
|
|
.bp
|
|
5-5 (note correction to correction - first $3F2 is ok)
|
|
.sp1
|
|
.nf
|
|
change $3F2 to handle your own RESETs, EOR (exclusive
|
|
OR) the new value at $3F3 with a $A5 and store the
|
|
result in the power-up byte.
|
|
.sp3
|
|
.fi
|
|
6-5
|
|
.sp1
|
|
NOTE: RWTS uses zero-page location
|
|
$48, which is also used by the
|
|
APPLE
|
|
monitor to hold the P-register value.
|
|
Location $48 should be set to zero
|
|
after each call to RWTS.
|
|
.sp3
|
|
6-11
|
|
.sp1
|
|
.nf
|
|
04/05 - Byte offset of current file position*
|
|
.sp1
|
|
.fi
|
|
*The current file position is updated
|
|
to point to the byte following the
|
|
data read or written.
|
|
.sp3
|
|
8-5
|
|
.sp1
|
|
.nf
|
|
9E51-9E7F An image of the DOS page 3 jump vector which the
|
|
above routine copies to $3D0-$3FF. See Chapter 5 for
|
|
a description of its contents.
|
|
.sp3
|
|
8-36
|
|
.sp1
|
|
B9A0-B9FF SEEKABS routine.
|
|
Move disk arm to desired track.
|
|
Calls arm move delay subroutine ($BA00).
|
|
.sp3
|
|
8-37
|
|
.sp1
|
|
BA00-BA10 Arm move delay subroutine.
|
|
.sp3
|
|
A-3
|
|
.sp1
|
|
.fi
|
|
A diskette containing these five
|
|
programs is available at a reasonable
|
|
cost directly from Quality Software,
|
|
6660 Reseda Blvd., Reseda, CA. or
|
|
telephone (213) 344-6599.
|
|
.bp
|
|
A-12
|
|
.sp1
|
|
at location $03 (the volume number
|
|
should match the volume number of the
|
|
other tracks), and then begin
|
|
execution at $800. INIT will return
|
|
to the monitor upon completion. If
|
|
the track can not be formatted for
|
|
some reason (eg. physical damage or
|
|
problems with the disk drive itself)
|
|
a return code is printed. For
|
|
example:
|
|
.sp3
|
|
A-20
|
|
.sp1
|
|
.nf
|
|
800G (Run the COPY program)
|
|
.br
|