MikeFulton

What's up, doc?

I've not tried Altirra. I'm working on a disk image management tool.

I am looking for information about the disk layout used by Atari DOS 3. Not interested in how to do DOS calls in BASIC or anything like that. I need to know things like the sector layout, directory format, VTOC info, etc. I have already googled for this, but the results don't seem to include any technical info. Thanks!

Everybody seems to be going out of their way to misunderstand what I'm saying. To be clear, I'm not talking about a single zip of the entire site. We were talking specifically about the Holmes stuff which was mentioned as being 700mb. A 700mb file isn't a huge download these days. I download bigger files all the time. A modern game demo could easily be 10 times bigger than that.

Had tried an older version long ago and just downloaded 2.2. I guess the big question is, what's the deal with the keyboard? I mean, I don't really want to hit Shift-2 on my PC keyboard to get a double-quote, even if that is how you do it on a real Atari 8-bit. Can't we have an option to use a translated keyboard? I didn't see the source or I'd jump in and just do it...

Sigh... Not saying that it should only be a single big archive. I'm saying that in addition to the individual file downloads, there should be a single ZIP with everything. Because a lot of people will want to download it all, and doing 6000 files of a 100kb each via FTP is extremely inefficient compared to doing a single big zip.

Strictly, an "IRQ" (Interrupt Request) is an electrical signal to the CPU from an outside source (like Antic or Pokey) telling the CPU "interrupt what you're doing and process this other thing". There are a wide variety of things which generate IRQs. Most common are timers and hardware events like the vertical blank for video, or things like control lines on an I/O port. On the 6502 and most other processors, an interrupt can be maskable or non-maskable. A maskable interrupt can be turned off or disabled in hardware, while a non-maskable interrupt (NMI) cannot. Typically, an NMI is used for things that are especially time sensitive. There are often certain conditions in the processor which generate a similar condition known as an exception, but this is not strictly the same thing as an IRQ. Also, people often say "IRQ" when they really just mean "interrupt" or "interrupt handler" (referring to the code that is called to process the interrupt) but this is not really correct usage. On the Atari, you get an IRQ from each vblank, and for any scanline where the display list indicates a DLI should occur. These are both NMI. A VBI or DLI routine would be an example of an interrupt handler processing the resulting interrupt. If your display list specifies a DLI to occur on the last scanline, the interrupt handler can take much longer than DLIs from other scanlines. By "disabling the VBI" and using the DLI instead, someone is trying to gain more time in the interrupt handler and still get the same 50/60hz timing that a VBI would provide. By the way, they're not really disabling the VBI interrupt at the hardware level, since it's an NMI that will always fire as long as the video is turned on. They're just disabling the handler that normally runs in response to the interrupt.

I was talking about the specific folder, not the entire archive. Although, a single ZIP for the entire archive wouldn't be a terrible idea either.

It wasn't presented as FTP... until now I didn't even notice that "ftp" was in the URL.

Whoever runs that site seriously needs to make an "everything.zip" file. I mean, it'd only be about 2 mb at most so why not?

First, FlashJazzCat, you were right about me counting from 0 instead of 1. However, it turns out that sector 5 on my disk image was corrupted, which is why it didn't make sense as a sector map. I started looking at the rest of the disk, which is mostly ACTION! source code, and found a few sectors that have garbage intermingled with the expected ATASCII text. This got me wondering, so I dug out an archive CD-R which had all my old 8-bit stuff on it. When I looked at that version of the same file I discovered they didn't match. Somewhere along the way, things got messed up. So now I'm starting over with new image files, freshly formatted. Thanks for your time, everybody!

Not an ATR. It's XFD, no header. I'm writing code that reads existing disks. Don't really have the option of specifying a particular version. I will double check that idea later when I'm not on my iPad. However, the sector preceding the directory info didn't appear to be a sector map, so there's still that.

Can someone post the disk images here?

That's not what I'm seeing with my SpartaDOS Construction Set disks. There is no sector map and the main directory starts at sector 5. Can you put a file or two on there and post an image file?

Thanks for the link. Oddly, the file system is not explained in the programmer's guide, which I already had. Unfortunately, it looks like this manual is the source of the information on the webpage I was working from. The manual includes the same error, and doesn't say anything further about the main directory's sector map.