25
votes
Accepted
How are the randomizer values on the Apple II maintained?
It's incremented while waiting for keyboard input.
The 16-bit random seed (RNDL and RNDH) is updated by the KEYIN routine as it spins while waiting for a key press. KEYIN is used by the Monitor ROM's ...
- 641
16
votes
Accepted
What exactly was the intent and implementation of Apple DOS 3.3's volume concept?
I'm curious what the intent and actual implementation of the feature was.
It's meant to identify diskettes. Much like volume names on DOS or similar on other OS. In fact, Apple DOS was ahead, as ...
- 213k
16
votes
Accepted
What's the name of this Apple monitor
NEC Character Display, Model JB-1201M(A).
It’s a 12” monochrome green display, manufactured in Japan circa 1981. Approximate dimensions are 14” x 12” x 11 1/2”.
Further details found at:
https://www....
- 176
14
votes
Accepted
Is it possible to write unit tests in Applesoft BASIC?
Depends, as usual, on your of understanding what a 'Unit Test' is or has to be. But BASIC is no difference from any other language. Write your functions (subroutines in BASIC) and call them in a ...
- 213k
14
votes
Accepted
What's the correct Unicode code point for the Apple IIe's "delete" symbol?
TL;DR:
There is no 'REVERSE FIVE-BY-FIVE CENTERED CHECKER BOARD' (*1) in all of Unicode's blocks. Closest by looks and positioning might be the
"REVERSE FOUR-BY-FOUR CHECKER BOARD" U+1FBA6
...
- 213k
12
votes
How do I make an Apple II disk image with the sectors in physical order?
All nibble images are in physical order, by definition. It sounds like you want a sector image (a series of 256-byte sectors) in physical order. Note this only applies to 5.25" disks.
On the ...
- 8,775
11
votes
Accepted
Help understanding TAIPAN source code for the Apple II
You don't need to follow the listing far to see the problem.
Line 10 ends with GOTO 10000, and 10000 starts with CALL 6147, which is $1803, smack in the middle of the Applesoft source code, which ...
- 7,418
9
votes
What's the correct Unicode code point for the Apple IIe's "delete" symbol?
Only because @trikly asked (in this comment), from the relevant Unicode documentation(PDF), the three new "Specific symbols for delete" that have been accepted for future inclusion in the ...
- 331
8
votes
Accepted
How to change what program Apple ProDOS 'starts' when booting
Sorting the root directory to put the desired .SYSTEM program first will fix the issue.
You can sort a directory on a ProDOS disk with the ProSel-8 disk utilities or Copy II+. You can also just ...
- 8,775
8
votes
Accepted
Is it possible to detect Vertical Blanking on an Apple III
Yes, it is possible.
I'm annoyingly unable to find a simple technical reference, but from the Apple III SOS source code:
[Page 5]
2EF8: *
2EF8: * 6522 REGISTERS
2EF8: *
...
2EF8: E.IFR EQU $FEED
...
- 35.9k
7
votes
Accepted
Did any AppleSoft language enhancements patch CHRGOT?
Yes, programmers occasionally patched CHRGOT. It wasn't a common tactic because there were better ways to add user-defined commands and functions, but you might choose to patch CHRGOT if you wanted ...
7
votes
What were the differences of the various AE RamWorks cards?
What were the differences of the various AE RamWorks cards?
(Base Board) Memory size.
There were 3 versions produced by AE back in the day, the RamWorks, RamWorks II, and RamWorks III.
The original ...
- 213k
6
votes
What is the VTOC format for an AppleDOS disk with more than 50 tracks?
Summary of comments, plus analysis of "appleii640.img.gz" from the github issue page...
This is an 80-track, 16-sector disk. The interpretation of the sector in-use map in the DOS VTOC was ...
- 8,775
6
votes
What were the Apple II artifact colors?
The Apple II outputs a video signal that is close enough to NTSC specifications that composite monitors will attempt to display color, but deviates in ways that monitors are not particularly designed ...
- 34.7k
6
votes
Accepted
6502 Assembly on Apple IIe: GETLN fails with 'syntax error' under ProDOS
There are two basic approaches:
Disable the I/O hooks. This removes the operating system from the equation.
Write your own line input routine, using the keyboard I/O addresses ($c000 / $c010).
...
- 8,775
6
votes
How to read copy protected Apple II floppies / NIB images
There are various approaches using modified hardware, such as https://applesaucefdc.com/, that yield excellent results. WOZ files can handle all copy protection formats, including the fancy ones like ...
- 8,775
6
votes
Help understanding TAIPAN source code for the Apple II
You might have more luck with the BASIC program from this disk: Taipan Hayden Book Version, which was apparently keyed from the Taipan: A Historical Adventure For The Apple Computer book.
It at least ...
- 20.5k
5
votes
Is it possible to detect Vertical Blanking on an Apple III
According to the Apple III Standard Device Drivers Manual, the .CONSOLE device driver provides a function to wait for vertical blanking. This function could effectively replace the simple VBL polling ...
- 641
5
votes
Extensions to Apple BASIC with ampersands
A little late to the party but I remember doing this back in the early 80's, it was definitely the & "extension" used in Applesoft. Like Patrick mentioned I also remember combining ...
- 51
4
votes
6502 Assembly on Apple IIe: GETLN fails with 'syntax error' under ProDOS
Some aspects of the Apple II's I/O system are pretty clever. Others, not so much. IMHO, the worst aspect is the way I/O cards use one entry point for everything, meaning that it's not possible to ...
- 34.7k
4
votes
How do I make an Apple II disk image with the sectors in physical order?
As far as I know, every format in widespread use stores decoded sectors in DOS order, decoded blocks in ProDOS order, or raw track data (nibblized sectors).
If the sectors are numbered 0, 1, 2, ... in ...
- 1,951
4
votes
A2M6020 AppleColor monitor not showing color
The Apple IIc Color monitor and the Apple IIe Color monitor both have a color disable switch in the control panel behind the flap in the front. It's the button at the right. You don't write about ...
- 7,636
4
votes
Apple ][ nibble disk format specification
I've been generating documentation on various Apple II (and Macintosh) formats as part of the development of CiderPress II. The general layout of nibble data is described in this document, and the ...
- 8,775
4
votes
Accepted
Apple ][ nibble disk format specification
There is no spec as such, except for the behaviour defined by what Saltine's Super Transcopy program does. (It's a great hack using the track read code from Essential Data Duplicator as mentioned here....
- 7,418
4
votes
How to change what program Apple ProDOS 'starts' when booting
I would be astounded if the answer is to "delete everything and add files in the correct order"
Jup, that's 'a' solution :))
ProDOS only expects a single SYSTEM to exist on the boot volume. ...
- 213k
4
votes
What's the correct Unicode code point for the Apple IIe's "delete" symbol?
In order to determine what Unicode symbol should be associated with that character, one would have to ascertain what the dot pattern was supposed to represent. The particular pattern of dots used for ...
- 34.7k
3
votes
How to read copy protected Apple II floppies / NIB images
Partial answer:
(1) To see if a NIB image would do the job, try to copy the floppy with one the Apple II nibble copy programs (Locksmith etc) to another floppy. If that works, a nibble image will ...
- 26k
3
votes
Accepted
Why did ProDOS trace Applesoft?
IIRC using trace serves two purposes, both related to stability and performance:
Improving command detection
With TRACE enabled BASIC prints the line number `prefixed by a '#' character and suffixed ...
- 213k
3
votes
Motivation for DOS 3.3 using I/O hooks rather than ampersand-hook
As usual History and compatibility.
The Apple II was originally only released with Integer BASIC in ROM. Applesoft BASIC had to be loaded to RAM - not to mention that it was far from what we know, for ...
- 213k
3
votes
What were the alternative graphic cards for the Apple II?
One very high-resolution graphics card that could be used with Apple ][ and //e systems was the IO Research Pluto This went up to 1024x768, in up to 24-bit colour. It did not go inside the Apple case: ...
- 12.4k
Only top scored, non community-wiki answers of a minimum length are eligible