Questions tagged [apple-ii]
The Apple II series of personal computers and related software and hardware. Use [apple-iigs] for the Apple IIgs in particular, or [apple] for Apple hardware in general.
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What makes slot 7 of the Apple ][ unique from 1-6 and how was this used?
In the Apple II, there are three unique slots (depending on model):
Slot 0 (on the ][ / ][+) which is typically used for language cards.
"Aux" slots in the //e and IIgs, typically used for memory ...
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Why does Applesoft BASIC get confused by a nonzero value at $0800?
Applesoft BASIC programs start at location $0801 in memory (usually). If you put a nonzero value at address $0800, though, you get an error when you try to run the program:
?SYNTAX ERROR IN 65124
...
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Does every retrocomputer and console with NTSC composite output have 'artifact color' ability?
Artifact color is heavily associated with the Apple ][, since that is the only method the machine had to produce a color display. I was looking at the fantastic demo for IBM PC + CGA, 8088MPH, and I ...
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What are the differences between the versions of AppleSoft BASIC?
Apple did make some changes to AppleSoft BASIC over the years between the first version on the Apple II and the last version on the Enhanced IIe and IIe card. What are the differences between the ...
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What determines the color of every 8th pixel on the Apple II?
On the Apple II there's an interesting way to add a little color to the bitmap, since the high bit selects the palette used for the three-and-a-half pixels represented by the byte. Like this:
0: Black,...
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What is DRAM refresh and why is the weird Apple II video memory layout affected by it?
I've roughly known the concept for years, but never really understood it. Back in the day, two types of RAM typically used in home computers: static and dynamic RAM. Static RAM (SRAM) was apparently ...
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Over its lifetime, how many Apple II computers were sold?
It would be nice to break it down by model if possible.
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How much did the first hard drives for PCs cost?
I would like to know how much early PC hard drives cost but have only been aable to find adjacent or unsourced data.
According to the Centre for Computing History:
The "IBM 5161 Expansion ...
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How do I use shadowed memory to render Super Hi-Res quickly?
The Apple IIgs video memory is controlled by the 1MHz Mega II chip, so directly accessing the Super Hi-Res page in bank $E1 is slower than accessing other memory. How can I render in "fast" memory, ...
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On what Apple II and II+ keyboards can the ']' character be generated?
It had long been my impression that while brackets [ and ] could
be displayed by the Apple II, the standard Apple II keyboard was not
capable of generating them.
Some time ago I noticed that on this ...
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Apple II bus: IRQ and DMA priority
One of the weirdest misfeatures of the Apple II - and perhaps the dumbest thing Woz ever designed - is the vestigial priority system for IRQ and DMA on the Apple II expansion bus.
Each slot has four ...
- 748
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Applesoft (pseudo) Random Numbers - alternatives?
What are the alternatives (with examples on how to implement) to Applesoft RND(1) command? I have read of people using a completely different algorithm by poking machine code stored in a DATA ...
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Converting Apple II ProDOS blocks to DOS tracks and sectors
The 8-bit Apple II had two disk operating systems with different disk access semantics.
DOS used tracks and sectors. A sector is 256 bytes.
ProDOS used blocks. A block is 512 bytes.
But mapping ...
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How did Apple II BASIC programs protect against listing?
I seem to recall from my high-school days that certain Apple II programs protected themselves from being listed and therefore modified.
If you tried to do it, the machine would simply reboot.
How did ...
user6464
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How did Apple fail to tap the business and scientific markets?
Currently reading an excellent book called Blue Magic: The People, Power and Politics Behind the IBM Personal Computer, which is just what it says on the tin; highly recommended to anyone who wants to ...
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Absolute maximum number of nibbles on an Apple II floppy disk track?
The Apple 2's disk drive controller and 5¼" floppy disks have the following metrics:
The disks is spun at (roughly) 300 RPM (Revolutions per Minute), which means it takes = 1000 ms/sec / (300 RPM / ...
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Apple II: Applesoft BASIC memory management
I am trying to write an Applesoft / floating point BASIC program using high resolution graphics and some assembly language code.
My BASIC program is quite large, and after running the program for a ...
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Why did the original Apple //e have two sets of inverse video characters?
According to Apple II Technical notes Mouse #6, updated January 1989,
In unenhanced Apple IIe computers, the alternate character set contained two sets of inverse uppercase characters. In the ...
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How were binary subroutines embedded in Integer BASIC programs?
Programs written in Apple's Integer BASIC sometimes had bits of machine code embedded in them. This was more convenient than loading the code separately, especially when the program was loaded from ...
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Did the Apple IIe Platinum include all feature enhancements from the Apple II line?
Not including the Apple IIgs, did the Apple IIe Platinum include all enhancements made by Apple?
For example, the first Apple IIe couldn't utilize the Double Hi-Res mode from what I understand. In ...
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Can a retro-computer be a useful way to learn computer-architecture fundamentals?
I've been reading about the fundamentals of computer architecture, but I think I could get a better grasp of the basics if I could could have an actual device to play with.
I had considered building ...
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How do accelerators and CPU cards work on the Apple II?
An Amiga 1200 exposes the entire CPU bus on the expansion port, so that an accelerator only needs to assert BR which causes the onboard CPU to stop all computation and electrically disconnect from the ...
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How to write the Apple ][ HIRES pages to disk to make screenshots?
The Apple ][e had 2 HiRES video pages, HiRES animation involved switching between the 2 pages and redrawing the screen. A really early way to take an in game screenshot was to dump the computer with ...
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Apple IIe problem (can’t save and load files anymore)
I recently bought an Apple IIe at an auction. It was extremely cheap but worked. I have no experience with such old computers.
I just started the computer and wrote some BASIC programs for fun. ...
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What was the change to the Apple //e motherboard that allowed for Double HiRes graphics?
Double Hi-Res graphics (DHGR) was a nice addition to the Apple ][ line as it allowed for higher resolution 560x192 graphics with 16 colors in comparison to the traditional 280x192 with 6 colors. It ...
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Did the PAL version of the Apple II use a different clock frequency?
The Apple II used a 6502 CPU clocked at 1.023 MHz which was tightly tied to the NTSC frequency (1/14 of crystal, 3.5 color clocks per CPU cycle). It is well known that the Disk ][ was primarily ...
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1
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Odd tokenizing in Integer BASIC
While researching the underpinnings of Integer BASIC (IB), I came across an oddity I'm hoping someone can explain.
Unlike MS-derived systems, IB converted numeric constants to their 16-bit ...
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How to connect an Apple IIe to an external Sider hard disk drive
I am a sucker for 8 bit junk components, and recently picked up a Sider hard disk for my Apple //e. I was able to talk myself into the purchase by fondly remembering how I lusted after this piece of ...
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How was Prince of Persia "better/faster" with RWTS18?
I was reading about Prince of Persia over at POP Code Review. In that article, the writer printed an interview with Roland Gustafsson, the inventor of RWTS18 copy protection for the Apple II series.
...
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At what address do Apple II Applesoft programs get stored?
Online references disagree on whether Applesoft programs were stored at 0x801 (2049) or 0x3001 (12289). A quick test on my OpenEmulator install with an Apple II Plus definitely puts it at 0x801. ...
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What format is used for Apple II cassette tapes?
Apple II computers initially used audio cassette tapes for storage. How was the data stored? What was the maximum bit rate?
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How did the Lazer Systems Graphics Plus board work?
The first two Apple II models (the ][ and ][+) were unable to display lower case on the text screen. Some 3rd parties made lower-case adapters that replaced the character ROM (e.g. Dan Paymar's ...
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Is all 100% of a 64k Apple II memory usable?
Are there any areas of the 64k RAM which are permanently unusable by anything, whether by the built-in monitor ROM or user programs?
Looking at $C000-C0FF, this is the "softswitch" area, and as far ...
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Testing/using a joystick in AppleSoft?
How does one use joysticks in a program on the Apple //?
I have three different joysticks here and I would like to visualize their state (pot and button values), maybe similar to the SDL joystick ...
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Apple II SCSI: Maximum drive / partition size?
Using an "SCA to 50-pin adapter", it is possible to use a 300 gig Ultra-320 SCSI drive from 2004, with an Apple II outfitted with the Apple SCSI controller.
It seems possible for the electronics to ...
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How did the Microprofessor II have space for a Chinese font in the ROM?
There's an Apple II clone from Taiwan which apparently forgoes the text mode and just has a graphics mode because it's simpler that way to render Chinese writing.
It had a 16K ROM, of which 12K is a ...
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How does the Apple II address more than 128KB of RAM?
For the Apple //e, it was very common to have an extended 80-column card installed which brought the machine up to 128KB of RAM via 2 banks of 64KB each. There are soft switches in the $C0xx space ...
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Why would a Reset key bounce disconnect Apple DOS?
This answer stated that hitting the Apple II Reset key twice, in quick succession, could cause DOS to be disconnected from the I/O hooks. I don't understand why that would happen.
Quick background: ...
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Apple II: ProDOS partitions on floppy disks?
On the Apple II using ProDOS, was it possible to create partitions on a floppy disk? Would it be possible to have two or more partitions on a 140k 5.25" or 800k 3.5" disk?
(The question here is not ...
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How can I tell if an Apple II disk image is bootable?
I have around 500 floppy disk images from an Apple II and IIgs BBS/usergroup that closed down recently. Some of the disks are bootable, but many aren't. Is there an easy way to tell if a disk boots ...
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Origin of dealer networks
Roughly speaking, the two main ways to sell computers are, and particularly were in the old days,
Three digit price tag sold to individuals => mass market, department stores and suchlike.
Four digit ...
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What's the best way to hook up an external power supply to the Apple IIc without a 7-pin female DIN plug?
As seems to be typical with Apple IIc purchases these days, mine came
without the external power supply. I have ordered some 7-pin female
DIN plugs and other adapters that will let me plug a modern ...
- 24.6k
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What's the first use of the term, "1977 Trinity"?
The term "1977 trinity" has been used, here on Retrocomputing
SE and elsewhere, to refer to a set of three computers that
started shipping in mid- to late-1977: the Apple II, the TRS-80 ...
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9
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1
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What is the VTOC format for an AppleDOS disk with more than 50 tracks?
I am trying to read files of an AppleDOS 3.3 disk. The documentation I've found, both from Inside AppleDOS and also from Archiveteams' website (which I believe was taken from Inside AppleDOS): http://...
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Which wires need to be changed to use a Gotek floppy emulator on an Apple Mac?
Preamble
I own a Gotek floppy emulator that I use with my BBC Model B. It is the latest model with the Artery AT32F435 MCU1, so there is a lot of memory space and processing power for future features ...
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How could a 16-sector PROM Apple II access a 13-sector disk?
When the Disk ][ first came out for the Apple II, the PROMs on the interface card only knew how to work with a 13-sector format. Around 1980, the Disk ][ was updated with 16-sector PROMs either for ...
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How can I programmatically determine whether an Apple II .dsk disk image is a DOS .do image or a ProDOS .po image?
I'm interested in working with the most common Apple II disk image file format, .dsk.
(I only programmed these machines briefly in Basic around 1979-81 and have not been in the emulator scene, so I'm ...
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Why does _Beneath Apple DOS_ show FM encoding rather than GCR?
From the beginning in 1978 the Apple II floppy disk system used GCR
encoding to convert data bytes to sequences of binary values to
be written to the diskette: first 4-and-4 encoding (never released),
...
- 24.6k
6
votes
2
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How does the Apple II read lines for video display from the text-mode frame buffer?
(This question applies also to the low-resolution graphics video
buffer, since that uses the same frame buffer as text mode, just
displaying it differently.)
As described on page 1-12 et seq. of The ...
- 24.6k
6
votes
2
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Identifying the functionality of the memory select IC in Apple II
Three are ICs labeled memory select used in Apple II.
One to apply A6 on the three banks of RAM ICs.
One to generate /RAM_SEL applying the latched RAM output to the data bus.
And one to apply /CAS on ...
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