Rybags

There are emulators which work on both Mac and Linux. This link has some of them: http://vjetnam.hopto.org/index.php?frame=emu

Just create new images in the Disk Drives menu (ALT-D). They will then be a "blank flopppy" as far as the emu is concerned, just format it with DOS and write files to it. I prefer just using PC files, though, using the virtual hard-drives.

Enable the "H: patch" and point the hard drives to a PC directory. You can do without DOS in many cases, but it's best to have some .ATRs setup with your favourite DOS's.

You can't run 2 monitors at the same time (not without the same image, anyway). Fitting a second shifter chip, or a 3rd party graphics mod would be about the only way. I'm not sure, but there might be programs about which allow you to change modes without having to reboot. The switch would most likely be to switch the sensing off for monochrome - IIRC, the ST will reboot if you plug a mono monitor in while running in colour.

Star Raiders was a release title on the ST, but has nothing on the original. - The Addams Family (NES version was in the arcades) - Arkanoid, and sequels (?) - Black Dragon/Tiger (?) - Blasteroids (was an Atari arcade release) - Bomb Jack (?) - Centipede (?) - Double Dragon (?) - Dynablaster - Gauntlet - Golden Axe (?) - Klax - Marble Madness (?) - Missile Command - Pang - R-Type (?) - Rainbow Island (?) - Road Blasters (?) - Road Runner (?) - Sidewinder (?) - Slap Fight (?) - Space Invaders - Super Sprint - Star Wars (?) Just scrolled through my MAME list, some there I'm not sure about.

I don't think Star Raiders had an arcade version. Others: - Missile Command - Asteroids - Outrun - Xenon 2 (there was an limited release of Amiga arcade games) - Buggy Boy - Bubble Bobble There are plenty of others ... I never really got into ST gaming in a big way.

Capture cards usually do blending, with "comb filters". Some are good enough to blend frames so that the interlacing can't be seen, but with others you have to do post-processing to blend the frames (each frame odd/even on TV is usually from a consecutive timespan).

You can only plug 8-bitters directly into monitors which accept S-video or composite input (such as the Amiga's 1084 series), and you'll need a cable adaptor, or a mod to your machine to add the appropriate port. Otherwise, you can use a PC with a video capture card. Or, you can buy special convertors, but they would cost more than an old computer with capture card.

deltatst.zip OK. The popular "Delta" music .XEX file, hacked with my routine added to replace the normal bass sound which plays on channel 2, with a triangle waveform. Sure, it sounds crap because the frequency is rather out (translation tables need work), and it's playing a triangle wave where a guitar sound would be more appropriate, plus there's no ADSR (but that could be worked in with little trouble).

I reckon it could be incorporated into RMT. Different translation tables for the frequencies would have to be generated, and the RMT player would need a slight rewrite to spread the load (ie- not do all processing in 1 block of scanlines). Since RMT nicely keeps shadow copies of the sound registers, the program could be adapted to only generate its waveforms under certain conditions.

I'm fairly sure RMT "volume only" does it at the Vblank level, so only allowing 50 Hz tones. My routine does it at just under 8,000 samples / second, which allows complex waveforms.

Here's another little demo program "DEMOWAVT.XEX" demowavt.zip It plays 2 voices of wavetable sound (digitized) without screen blanking. It uses the VCOUNT wait technique similar to the 1-bit and 2-bit sound demos I posted before. The way the program is setup, wave tables up to 256 bytes in length can be used. 512 individual frequencies are available, although that could be increased fairly easily. To use the program, Load Exe from the emulator, or binary-load from DOS on a real machine. Use joystick 1 up/down to change the pitch - hold the button to do the other voice pitch. The waveforms can be selected from 9 that I've included. Just press the number or <shift> number to do the second voice. Note that key assignments mean you have to press the corresponding key if using the emulator (e.g. SHIFT-2 actually generates SHIFT-8 on Atari800Win). Waveforms: 1 - triangle, lower frequencies 2 - triangle, higher frequencies 3 - sawtooth, lower frequencies 4 - sawtooth, higher frequencies 5,6 - noise (high and low volume) 7,8 - short and long pulse-waves 9 - square wave (much the same as normal Atari "pure" sounds) 0 - Mute Mac/65 source code included. It can easily be modified to include customised waveforms. Note that the first byte in each wave table is the length (-1) of the waveform. Due to the way the program works, it should be 1,3,7,15,31,63,127,255. This program could easily be used in conjunction with conventional a conventional music player, provided it has reasonably tight coding.

Nice design. Almost identical to the one I built, except yours is somewhat neater (based mine on plans from elsewhere). I use a header plug on my daughterboard though, which goes to the DB9 plug (makes it easier to remove the motherboard from the XE without removing any other plugs or wiring).

Lots of games were single-stage load only. Can't really think of specific ones, since I gave tapes up > 20 years ago. Single-stage games were extremely easy to transfer to disk. Multi-stage ones usually just involved looking at 200 bytes or so of code to work out where they loaded and if they had any encryption (which wasn't often).

The good emulators like Atari800Win+ behave almost exactly like a real machine. That includes "illegal" 6502 operations, and most of the bugs/features of the hardware. For the average program, there will be absolutely no difference. Use the virtual disk drives to mount .ATR images, and enable the "H:" device patch, and point it to a PC directory so you can directly save to PC files.

Emulator for those without A8 hardware: http://atariarea.histeria.pl/PLus/index_us.htm Here is a GTIA version. I was expecting something unrecognisable, but the quality is almost as good. I just patched the program to store to $D01F instead, so the data is still the same (although half the data becomes redundant): demo1bit.zip Can someone try it out on a real 400/800? I've only got XL/XE's.

Wavetable playback is another thing I've done a little work on. Aside from the normal delay loop method, I've thought of 2 other possibilities for playback control: - POKEY Timers. Disadvantage is that there's a fair amount of overhead, and not really a huge increase in sound quality with the screen enabled (as compared to using loops). - DLI waiting. A little used feature of ANTIC. The high bit of the NMIST register is actually set when a DLI is requested, regardless of if they are enabled. It is reset at a later stage on the same scanline (the CPU doesn't have to store into NMIRES, like it does with a VBI). So, just generate a hires 240 line DLIST with DLI on every line, but don't enable DLIs. Then, the code just has to wait, with a BIT NMIST ; BPL WAIT sequence.

Ghostbusters: unsure. POKEY is used here. GTIA is only 1-bit sound. I aim to play around with it at a later time. From what I've read, the C-64 Imp. Mission uses some sort of compression algorithm on it's samples (but still playback is 4-bit). I'll have to try and see if it can be "reverse engineered". Next possible logical step with 2-bit might be to try and increase the quality by doing "oversampling" - average values to smooth out the steps. But, the main reasons for doing VCOUNT frequency playback: - playback is almost the same rate on both PAL and NTSC - short DLI and VBLANK routines can still be run, with minimum degredation of the sound quality - no screen blanking

Just a quick demo here, demonstrating the playing of digitized sounds with 2-bit samples. The quality is fairly reasonable, and no screen blanking is used. It just disables VBIs to stop that 50 Hz stutter. Rather than use delay loops, it waits on VCOUNT, which has the advantage of not having it's timing affected by screen DMA. I've tried using WSYNC, but you get some distortion due to "badlines" using that technique. The disadvantage of such a technique, of course, is that it isn't so useful for variable pitch effects for music. The program/data resides from $3F00 - $6F00. Just use "Load executable" in A800Win+ or binary load from DOS on a real machine. The digitized soundtrack (which you all should recognize) was sampled in Audacity, by feeding the PC speaker back to Mic, and sampled at 96,000/second. I then amplified the waveform (to normalize it), then wrote a program on the Atari to pack every 12th sample into a file. Each byte contains four 2 bit sample values, packed in order 4,3,1,2 (makes it quicker to shift into the right place). demo2bit.zip

There's little difference in most analog capture cards. In fact with both digital and analog, there's only 3 or 4 chipsets which most makers use. The biggest difference is usually in the bundled software (which often is crap). But, with analog devices, VirtualDub is a must-have, and it's free anyway. I have a Compro DVB-T300, which is a hybrid (it does digital and analog TV). It can also display 2 or more channels (although they have to be on the one frequency). It all depends on your needs. You can spend close $200+ on the latest/greatest digital cards, many now have PIP and can do 2 seperate frequencies at once, or just get a budget analog capture device for under $50.

My 800XL came with a cable with an inline "black-box" which undoubtedly contains a ferrite inductor coil (I think that's it) which greatly reduces RFI compared to a normal cable. Capture cards don't have very good RF shielding, and as a result cop heaps of RFI (most of which is generated by other components in the PC). Using composite or S-Vid results in a much better picture.

The composite/S-Vid approach is much better. I own 3 capture cards, and they all get some degree of interference in TV mode, no matter how good the source is.

A capture card is the best option. In conjunction (preferably) with an S-Video mod. Your PC doesn't need much grunt to just pass-through an input stream, and it has the added advantages of showing the overscan area, and blending frames (ie - no flicker) - but it can be undesirable at times.

That's just his reaction after realising he accidentally bought his kids 5 Intellivision games for Christmas instead of 2600 carts. Original image:

The coin-op variant had "Coin detected in pocket" as part of the attract-mode.