33

The simple answer is that early operating systems for the systems you mention did not provide those features. Apple DOS, for example, makes no use of interrupts, and has no concept of processes or memory protection. Nor does DOS have any concept of hardware drivers, as it includes support to drive the Disk II (a deep assumption in DOS) and nothing else. ...


28

For "home" computer systems such as the Apple II, the "operating system" wasn't anything like a modern one with processes and device drivers and so on; by the standards of modern OSes there wasn't really one at all. As a warning: all these explanations (long as they are) are for the most part considerably simplified. This answer is ...


24

If you don't know, then the answer is "no". It certainly is possible to get a color CRT tube and matching electronics and fit them into a cleared out case. However, if you have to ask people on the internet, then I'm pretty sure that the responsible answer to give you is: Keep your hands off. CRT tubes are high voltage electronics. They are evacuated, i.e. ...


24

DRAM requires that each row of the memory is read and re-written regularly, every few tens of milliseconds at least. This is made much easier by the DRAM chip having a row buffer which is filled with the contents of the row every time the /RAS strobe is triggered, and written back when it is released. So it is only necessary for the computer to arrange for ...


21

Keyboard Switch On the International version Apple IIc the keyboard switch swiched between a country-specific layout and and a standard U.S. layout. On the USA version it switches between the standard QWERTY and a Dvorak layout. (This was not so much a desired feature as a side effect of having to build the European version with a keyboard switch; putting a ...


20

Summary Each DRAM chip has multiple "rows" of memory, and each row needs to be accessed in a certain way (not necessarily via a read or write) on a regular basis in order to avoid the memory "fading away." (Basically, this access recharges the capacitors from which the DRAM row is made.) The Apple II uses two tricks to do this refresh. ...


20

No, you can't substitute; the 6502A was used precisely because it is faster for some things, even when not run at a higher clock rate. Apple IIe Technical Note #2: Hardware Protocol for Doing DMA (starting on page 2 of that PDF) explains this. On page 4 of 9 of the note it says: In the Apple IIe a 6502A, a 2 MHz part is used instead of the 1 MHz 6502 ...


17

We talk about the late 1970s and mainstream 6502 machines, right? It wasn't so much that programs run under OS control as that OS was a support function to Programs. More like what we would today see as a standard library with routines supporting simple I/O abstraction plus basic file handling on the user side and hard coded drivers within. Some, like ...


17

According to the Wikipedia article: The keyboard layout mirrored that of the Apple IIe; however, the “Reset” key had been moved above the “Esc” key. Two toggle switches were also located in the same area: an “80/40”-column switch for (specially written) software to detect which text video mode to start up in, and a “Keyboard” switch to select between ...


15

How is the Apple II text flash mode timed? It's a fixed timing signal generated by an NE555 timer (at position B3 on the original II+). (From the Apple II Reference Manual / Red Book p.151) Entering the values of C/R1/R2 into an online calculator for NE555s will give about 2.1 seconds cycle time (*1) The II's video logic used bit 2^6 and 2^7 to control ...


14

If you're happy to copy files and use Sneakernet then you could use a disk emulator like Floppy Emu, SDFloppy II, wDrive, etc. (Obviously all product links in this answer are likely to break in the future.) Note that SmartPort disk emulators require at least a ROM 0 //c. Instructions for upgrading are given here. There are various upgrade kits that include ...


14

The typical Apple II joystick appears to the computer as a pair of analog game paddles and two buttons. The easiest way to read the joystick position is from Applesoft BASIC, using PDL(n). The process is detailed in this post. The joystick X axis is PDL(0), the Y axis is PDL(1). You can do much better with a custom routine. The reason for this requires ...


13

Most of the reference material for the Apple II that I have seen refers to the 4116 RAM chip which held 16x1 kbit. Jup, at the time the Apple II really took off, 4116 chips had already dropped to less than twice the price of 4104, making any use of 4104 impractical. Not many were delivered using 4104, and while some users may have had 4104, they all soon ...


13

Unless I'm mistaken, these mean add/subtract zero. Almost. It means add/subtract zero plus carry. So if the Carry flag is set, then adc #$00 will increment the accumulator by one. Otherwise, the same instruction will leave the accumulator alone. Separately, the adc instruction may also set or clear the carry flags, if incrementing the accumulator meant ...


12

You can find the hi-res drawing code in an Applesoft disassembly. HPLOT starts at $F6FE. The ROM code is optimized for size, and parts are tricky to sort out. If you want something a bit more straightforward, you can find Applesoft-ish line drawing in fdraw. Some commentary on how Applesoft's line drawing code sets bits on the hi-res screen can be found ...


12

The typical circa-1980 8-bit CPU provided almost no support for modern operating system features. It was often possible to add such support using external logic, but very few machines actually did so because it would have added costs to the hardware with little practical benefit. Even many minicomputers of the time left those features out, at least in the ...


12

(It is assumed that this question is about the II or II+, not any later or third party model) TL;DR: Can the ] character really be generated on all unmodified Apple II (and Apple II+) keyboards with Shift-M? Yes. Are there any other "hidden" characters like this? Straight away no, but the original II and very early II+ keyboards (with MM5740 ...


12

Yes, there are at least a couple: LinApple - for Linux/Raspberry Pi. This fork of LinApple is current and maintained, and fixes annoying configuration bugs that others hadn't addressed. AppleWin — for Windows. Further to Thorbjørn Ravn Andersen's comment, I can confirm that Applesoft BASIC in JavaScript runs quite happily from a standalone local ...


12

It does not appear it saves times or memory in either the encode or decode, but maybe I'm missing something? Well, it kind of simplify decoding. The values $B0..$B9 are exactly what's uses to mark up numbers in literals and variable names. And here they as well simplify the interpreter. In Integer BASIC all tokens are encoded with high bit off, while ...


11

Yes, of course. Just keep in mind, it's not only the tube to be replaced, but the electronics as well. Essentially only keeping the shell. The 9 inch tube is of standard size, so finding one with the same mountings should be possible. Colour tubes do (usually) need more depth, which shoulf still be possible as the IIc monitor housing is rather long. That ...


11

Though Thomas Jager is correct in his answer, I'll add a bit about the practicality of those switches for a USA model. The 40/80 column switch never appeared to do anything in any of the software I used. Though it has been years since I used a //c, I think it might have set the display mode at startup (i.e. pushed in, the computer would boot in 80 columns). ...


10

Contemporary operating systems for the 6502 did not have those features. But not because they couldn't. It just wasn't considered necessary or desirable. Provide automatic switching between processes. The standard trick here is to have a clock attached to an interrupt that the OS can use to perform a context switch. This seems doable on the 6502 with ...


10

There's a full clone of a revision 0 Apple II motherboard made by one avid retrocomputing enthusiast. He no longer has kits for sale, but the board Gerber files are available. Order some boards from a PCB manufacturer, source the components, and you'll have everything to build your own complete Apple II mainboard.


9

If you're really willing to do some jiggery-pokery, find some small gauge solid copper wire (like the twisted pairs from a CAT5 cable - I like to cannibalize old multi-conductor telecom cables) and get yourself two longish bits of wire. Strip the insulation back about 1 inch on one end of both wires. Now find a toothpick or something very close to the ...


9

Page references below refer to the Apple II Reference Manual, 1979 edition. As well as Integer BASIC itself, the following machine-language features were lost: The miniassembler (p.49), allowing one to type in 6502 opcodes that it would assemble into memory. (The format was the same as the monitor's L "list" command printed.) While it didn't support ...


9

I realize the OP asked specifically about Assembly Language, but I felt strongly enough about the quality of "Machine Language for Beginners" that I wanted to post it as an answer. Given that the Apple IIe has a pretty decent built-in monitor, this book is a natural fit for getting the basics down. I completely understand the utility of a good assembler, ...


9

You can't tell if a .do/.po disk image file is in DOS order or ProDOS order unless you recognize something on the disk. If it has a DOS 3.3 or ProDOS filesystem, it's pretty easy. Otherwise... not so easy. If you want to see how CiderPress does it, take a look at the AnalyzeImageFile function here. After peeling off .gz/.zip, it checks the file extension....


8

You might want to investigate ADTPro. Since you are using an Apple //c, which already has a serial port, you can easily bootstrap the software by connecting the //c to another computer via a serial cable and/or NULL modem and simply issuing an IN#2 on the Apple. Once you have ADTPro running, you can start transferring disk images via the serial cable to ...


8

Another partial answer. .d13 is a format for storing the 13-sector floppy disks that were used on the Apple II before mid-1980, by Apple OS's before before DOS 3.3; i.e. Apple DOS 3.1, 3.2 and 3.2.1, the earliest versions of Microsoft's Softcard-based Apple CP/M 2.2, and maybe by the first version of Apple PASCAL (not sure about that though); those floppies ...


8

What exactly is DRAM refresh? Is it simply making sure a memory cell is accessed which gives it an electrical charge to keep it alive, or is it more like a 'read and re-write'? Both. DRAM stores it's information in the charge of a capacitor(*1). Capacitors leak. Chip capacitors leak faster than discrete ones,and small ones even faster (*2)- DRAM chips have ...


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