cd-w

Here is a version of Juno First modified to work on the ATGames Atari Flashback Portable (FBP) device. The speech and savekey/highscore support have been removed as this will never work on the FBP. Please let me know if you find any issues. To get it working, unzip the attachment and copy the "Juno1.bin" file into the "Game" folder on your SD card. Chris Juno1_FBP_Alpha_01.zip

After testing a few more permutations, the problem appears to be the detection of F4 bankswitching in the FBP rather than the code itself. It seems the FBP needs a lot of evidence of F4 bankswitching before it will select this method. The attached code is identical to the previous one, but with the blank space filled with bankswitching ("sta $FFF4, etc.") instructions. So far, I have found the following with the FBP: TIA emulation is rather basic - early HMOVEs don't work, and sprite positioning is off by a few pixels. Bankswitching detection could be better. Some illegal opcodes appear to work, e.g. LAX, NOP variations Chris f4test_working.zip

I'm having some difficulty getting basic F4 bankswitching working on the Atari Flashback Portable (FBP). I was investigating why Juno First doesn't work on the FBP and immediately hit an issue with the bankswitching. I have written the simplest possible bankswitching test (see attached), but the FBP just hangs when I run it. I initially assumed that the FBP didn't support F4 bankswitching, but then I encountered this thread with some F4 bankswitch conversions: http://atariage.com/forums/topic/258970-atari-flashback-portable-compatibility-list/?p=3653305 The F4 versions (e.g. Gyruss and Mr Do's castle) work fine on the FBP. Does anyone have any theories why my bankswitching code might be choking the FBP? Thanks, Chris f4test.zip

The harmony is available new here, and the starpath images are widely available to download: http://harmony.atariage.com/Site/Harmony.html

Nice project - the Harmony cart for the Atari 2600 is implemented this way also - using an LPC2103 microcontroller connected to the 2600 bus. Some recent homebrew games, e.g. Space Rocks, are written in C and execute on the microcontroller, using the 2600 only for the display. Chris

Try a different cable - some are wired only for power and not data. Chris

It is a bit of a waste of ROM, but the ARM really likes 32-bit values, so you could do the conversions at compile-time and define your sprite data as: data | color<<4 | PAL(color)<<8 | SECAM(color)<<16 // PAL & SECAM are C macros The fetcher code would then be: unsigned int sprite = spriteData[x++]; fetcher[data++] = sprite & 0xFF; fetcher[color++] = (sprite >> TVshift) & 0xFF; Or something like that Chris

Why does interlace suck? On a CRT screen the flicker is hardly noticeable. Many Atari games use flicker, and a constant 30hz interlace looks far better than 15hz flicker. I agree that it looks poor on an LCD TV, but that is because the image is not handled properly by the TV. Chris

Excellent - I wasn't sure this would ever see the light of day. I've got a long plane ride coming up and now have my entertainment planned out. You should ask Al to post this up on the front page? Chris

I suspect some minor difference in the clock between the two consoles. The code requires the TIA and 6507 to be synchronized, and any drift could cause the effects your are seeing. That said, it is strange that the original 32text demo works fine, suggesting that the timings are not too far out ... Chris

I suspect the Jr is one of the late TIA89 models that doesn't support the early HMOVE trick used to display the text. There is no way to display the text on these consoles, but they are relatively rare so it is not an issue for most people. Is the console a PAL or NTSC model - I think TIA89 was more common on PAL? A screenshot would help us identify if this is the problem. Tightly fitting carts are a known problem on the 7800 - the build quality of the later ones was very poor. However, in your case it sounds like the tabs to open the dust flaps have snapped off? Chris

The dreamcast battery is rechargeable - try leaving your console switched on for a while. I highly recommend a GDEmu device (SD card adaptor for the dreamcast) - a bit expensive, but you won't need to open any sealed games: https://gdemu.wordpress.com/ They are only sold periodically, so you need to keep checking the site. Chris

I did, but can't remember the details now . I should take a look at the code again ... Chris

It is possible to do this by switching VBLANK on and off at the edges? Chris

Last active in 2013: http://atariage.com/forums/user/17256-devin/

Thanks Darrell - looking forward to it. Chris

Darrell - Can you send me the BUS bank-switching spec that you have produced - I'm interested in coding it up for the Harmony/Melody? Thomas - The bank-switching/bus-stuffing code is timing critical so it is better to code it up in ARM assembly. You should definitely learn ARM assembler - it is very friendly for coding directly by hand. The 16-bit THUMB instruction set is quite close to 6502 and will take you about a day to learn. The 32-bit ARM instruction set is great for short fragments of high performing code as you can do a lot with each instruction. The new Cortex THUMB2 instruction set combines the best aspects of THUMB/ARM but isn't applicable to the Harmony/Melody (which is an ARM7TDMI chip). A very quick tour of ARM assembly written by a friend of mine can be found here: http://www.davespace.co.uk/arm/introduction-to-arm/ The best references for ARM programming are the official ARM manuals and Gameboy Advance programming resources: ARM/THUMB quick reference: http://infocenter.arm.com/help/topic/com.arm.doc.qrc0001l/QRC0001_UAL.pdf ARM7 Manual: https://ece.uwaterloo.ca/~ece222/ARM/ARM7-TDMI-manual-pt3.pdf GBATEK ARM CPU guide: http://problemkaputt.de/gbatek.htm#armcpureference ARM Whirlwind tour: http://www.coranac.com/tonc/text/asm.htm Chris

That looks like emacs on a WYSE terminal! I used a similar setup back in the early 90s. I miss the distraction free experience, but the lack of graphics was a pain sometimes. Chris

Great presentation - pity it was so poorly attended! The lack of TIA music is an issue for us games programmers also. I really hope your tool will encourage more chip musicians to consider the 2600. Have you considered updating the audio registers more than once per frame? This could be a good approach for combining instrument and percussion sounds. The siren in star castle arcade is updated 4 times per frame. More frequent updates would also allow rudimentary samples to be played like the NES DMC channel. Though this would not work well with 4K demos! Chris

Cab you add me to the list also - thanks!

You should visit this place in Dublin: http://therage.ie Chris

Yes - look in vcs.h

The # is evaluated at compile (assembly) time so it cannot read the value of a memory address - all it does is take the literal value of the symbol. Chris

Maybe you will implement Elite fully now Chris

Thanks - the 128 pixel kernel has only 2 cycles spare, so there is not enough space to extend to 160 pixels in this version. However, the ball sprite takes us quite a few cycles, so if that could be eliminated it would free up some space. Even so, I'm not sure how to generate a RESPx start signal on the left edge of the screen without leaving a gap ... Chris