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universal2600

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About universal2600

  • Rank
    Chopper Commander
  • Birthday 12/04/1996

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  • Gender
    Male
  • Location
    South Carolina, USA
  • Interests
    Electrical hardware engineering, future physicist, being an OG nerd...🤔😶😁

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  1. Quick question, so I've been working off and on with this, mainly what I have now, would be a system where all the base. Addresses are the same as a stock vcs, but now the mirrored locations would access ram, atmega, and 8910, effectively by bankswitching, the bankswitch logic and the 8910 needs its own encoding, since it's uses a multiplexed bus, (needs a 2-bit value to control R/W and as data or register r/w), which is what I'm working on..... Plus I thought about grabbing an atmega644, 21.47727 clock, and to swap it in a vcs board, technically speaking, since it's 6x faster than the Tia, and 18 times faster than the 6507, most instructions usually take 1-2 clocks, while the max is 5 cycles for interrupts and jumps, so instead of 76 instructions per line..now you have 1368 instructions per line, ≈ 21.47727 million per frame, so there's plenty of time to get things done, I can also use the clkout fuse with a divide by 6 to generate the Tia clock
  2. necrobump, this project is actually still active, my hackaday listing has over 2,000 followers, so i guess time for an update: recently current events gave some time to work on it, so far i've settled on using a 6502, riot, tia, atmega8515, and ay-3-8910, and 64k of sram (cxk58256, 32kb ported via 8910 with the other 32k accessed via 8515), basic vcs software(any code that strictly uses $0000 - $007F for tia, $0080- $00ff for 128bytes, $0200 - $02FF for riot, and $1000 - $1FFF to cartridge, with $2000 - $FFFF being mostly unused with a13-a15 used to address the atmega8515 (this would be programmed to act as a sorts of antic/ram dma interface use the atmega to feed the tia or to modify memory locations, this would be also clocked @ 6x times the tia speed @ 21.47727MHZ) a7,a9, and a12 is still used but are fed instead into a 74hc138 and hex inverter (and a few signal diodes) to generate up to 8 usable chip selects ( in this design the mirrored addresses were ignored [remapped] using the 138 so probably any vcs bank switching won't work over 8k, if a7 and a9 are both high then an output is used to select the 128bytes, else the riot, if a12 is high then rom is enabled regardless of a7 and a9) im designing custom pcb, once i get it cleaned up enough i will look into getting a small batch made (board is currently 6.25 x 4.25 inches in size) just a lil update
  3. Lmao I ran into this thread browsing the internet, I was reading through it and thought well why not just use a 68008, I was thinking of a pbi accelerator that would contain it plus 64k of ram, use the 68008 for graphics, and the 6502 for logic,io, and sound...or vice versa, run it ~ 7.16 MHz to start, effectively a stripped down Amiga with an 8bit databus (Amiga XL?🙃)
  4. Well it's one of those emi filter/choke from a microwave, I could add some ceramic caps and a zener or two to help regulate and further smooth the power, I've also noticed the lines are way worse on my usb2683 frame grabber, using the composite directly on the LCD I can't see really them (tv may also be removing noise and filtering the signal), but it's clear as day on the capture card, I haven't got any spare svideo plugs so I haven't used svideo though I think my lines are mainly bus interference and old components in the video mixing area, I think swapping c53 on mine should help fix it aswell I've noticed these same lines on vcs hardware aswell
  5. The cap didn't make much difference, though after some figuring, I've noticed power supply noise can also cause jailbars, I use 2-3amp USB chargers and my authentic apple 10w supply produces way worse jail bars, and it's being filtered (USB cord goes through an emi filter and the atari plug on the other end), I have an 800xl ntsc, also with an internal Newell 256k(board is 1985 copyright), I've also noticed if I touch c53 also can affect the jail bars, which I believe is a 40pf ceramic, I don't have any 40pf atm so I'll have to swap out that one when I get ahold of some, plus the vertical bands are more pattern like, they show up in groups and look like the gtia test program, I've noticed turning the color pot changes where onscreen the bands appear, it's only noticeable on the basic screen, I don't see/notice it much when running demos or games This unit is pretty early, low serial #366x1 where x is rubbed off, so it'd probably be good to check the caps, I swapped in the newer antic, and added dual pokey aswell the (original) chips are dated first half of '83 🙃
  6. I've also found if using the stock video from the din, replacing the cd4050 can also help aswell, I use my xl with composite and after swapping it out, the line are much fainter, I'll try swapping out the cap aswell
  7. Interesting makes me curious what if one used a Motorola 68008 cpu 🤔🙃
  8. stereo ay via the cart port thats interesting, that would work though i'd like to have have access to the 64k of ported gpio space, plus i would be able to use more than 4MB of ram using the 2 8910 ports🙃
  9. True, unfortunately I don't have an ST, next computer I'd like to buy would be c128 only cause I had one when i was a kid, also a commodore Colt (I'm 23 btw which is the surprising part😂), price wise I'd get a c64...any way this idea was based around my 6502 2600 project, since the xl pretty much has everything I need minus Tia, atmega, and GI,ay,ym, so I might as well simply connect them via pbi, It'd make debugging and writing code less of a hassle, essentially this would be equivalent nowadays as a prototype devkit I guess
  10. Interesting, I know the ay isn't the most powerful psg, but as mentioned it has features the pokey doesn't, (iirc some basic adsr and envelope control, and wider frequency range, I think ym chips have fm synth) and to me the ay chips can sound kinda like a cross of nes, pokey, Sid mix depending what you're doing and sound demos I've listened to, one question if you eliminate the need for refresh (sram conversation) would it then be feasible to try driving the Tia, I do have some atmega8515, which could sit between the 6502 and Tia (I'd clock it at 21.47727mhz 6x the Tia clock to act as a hardware framebuffer, if using a 644), but mainly atm it's mostly for the 8 channel sound using spare parts
  11. Ok I see, yeah just looked at the pinout connecting it should be easy shouldn't need complex glue logic though I dunno if the Newell board (I believe it's 192k total as the board only has decode logic and replaces the upper 74ls151, and seems the base ram was replaced) will play nicely, I know I'll have to have some decoding logic for the 8910 (I know I need to generate iirc a 4 bit control bus for bdir, my system is ntsc and so is my Tia (full 128 color Palette 😁) so the Tia would need to run at ntsc colorburst 3.579545mhz, which I have some of those tiny smd oscillator which I would use for the clock, tia rdy would be connected to irq for sync, it's data bus directly controlled by the 6502, while it's address space would be ported via 8910 writes. I'm certain 8 channel sound would be possible, video would be interesting, if possible then one can make an XL "2600" compatible , though one would have to remap the code so it know where all the bits need to go, or some sort of "pseudo-emulator" that could translate address PS technically isn't the ay-3-8910 a psg and pia in one...well psg and ported gpio, plus 8910 has more flexible sound compared to pokey, imho it's 1/3 Atari, 1/3 Nintendo, and 1/3 sid🙃
  12. Makes sense, well my 800 has a 256k Newell board (ramdisk switch for original and "Sparta" I assume for Spartados?) So ram isn't really an issue, mainly I was thinking of using the 8910 via pbi to Port the Tia address space, and also it's control signals , and use the pbi databus to communicate to the Tia, pretty my 6502 Atari project in a nutshell, minus a 6532, this would be a "functional prototype", also use irq for Tia rdy for syncing writes, 8 channel sound with 2600 "emulation"
  13. Hi just a quick question, is how easily could one interface a ay-3-8910 via pbi (also is the pbi capable of driving a Tia from a 2600), to add enhanced sound, and an extra port which could also be utilized for bankswitching purposes (ram or more i/o devices [cowbell]),
  14. I'm building mainly out of curiosity, really I have the 6502, 6532, tia, ay38910, 64k sram, and atmega 644, the 644 I would clock at 21.47727 (6x) tia clock and pretty much use it kinda like the Antic chip, there's enough ram to store a full framebuffer, and allows me to use the 6502 to do other things, and i didn't mean that I could get the tia to produce nes like graphics, but produce something that (hopefully) looks and sounds way better than the vcs PS I did at one point think about using the gtia and pokey to be honest.... And it's cheaper using this chipset, and all parts except the tia can be bought new
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