electrotrains Posted April 1, 2016 Share Posted April 1, 2016 (edited) Thanks to the efforts of foft (Mark Watson) and his Atari FPGA project, there is an open source FPGA pokey implementation available. As a little Easter bank holiday project, I thought I'd have a go at using it to make a dual pokey cartridge using a prototype of the Ultimate Cart as the starting point... Two of the fpga pins act as audio left and right, and I've hooked them up to a low pass filter on some perfboard, along with a 3.5mm stereo jack (which leads to my TV's audio input). It was pretty easy to make a firmware for the Ultimate Cart that included two of foft's pokeys, his DAC and a bit of VHDL to hook them up to the cartridge port. Then I modified TMC and RMTPlayer (with a hex editor) to output to the two pokeys at $D50x and $D58x. I guess technically this atari has 3 pokeys now (one inside, and two on the cartridge). The two pokeys use about 10% of the Ultimate Cart's FPGA, so there is plenty room for more. This was just for fun, and perhaps to show a little of what is possible with a FPGA hooked up to the cart port. To make a proper external dual pokey, we'd probably want to use ECI+Cart port, so the pokeys could appear in the correct places in the memory map. MP3 of TMC playing via the dual pokeys attached. SynthyGambol_vhdl_pokey.mp3 Edited April 1, 2016 by electrotrains 11 Quote Link to comment Share on other sites More sharing options...
TheMontezuma Posted April 1, 2016 Share Posted April 1, 2016 What about SIDs? Quote Link to comment Share on other sites More sharing options...
+MrFish Posted April 1, 2016 Share Posted April 1, 2016 Nice choice of tunes btw. Haven't heard that one from X-Ray in a while. Quote Link to comment Share on other sites More sharing options...
Level42 Posted April 1, 2016 Share Posted April 1, 2016 Very cool, I can never get enough of POKEY, especially stereo Quote Link to comment Share on other sites More sharing options...
gozar Posted April 1, 2016 Share Posted April 1, 2016 I'm assuming this can't be added to the current Ultimate cart? :-) 1 Quote Link to comment Share on other sites More sharing options...
electrotrains Posted April 1, 2016 Author Share Posted April 1, 2016 I'm assuming this can't be added to the current Ultimate cart? :-) The need for the low pass filter (2 resistors + 2 caps) and headphone jack would make it a pretty messy addition to the board as it stands, which is why I haven't posted the firmware or source for this. Also, although there are spare pins on the FPGA, they are not brought out to a header. Of course someone could always redesign the PCB a bit, and add an audio jack to the board. Then there could be an option on the boot menu to enable dual pokey mode... or SID mode... or.... But I think that it would be better still to make a PBI/ECI+Cart version of the ultimate cart, then the pokeys could live at their normal location. Plus it could act as a RAM expansion too. SD Multicart + 1 Meg RAM + Dual pokey all one one board - that would be a nice thing! 5 Quote Link to comment Share on other sites More sharing options...
gozar Posted April 1, 2016 Share Posted April 1, 2016 Well, if you're going to add all that, then add alternate OS mode, stackable carts, and SD card access as a hard drive. :-) That would be an amazing device. Oh, and an RTC. (Cart mode wouldn't work on the PBI, right?) Sent from my iPhone using Tapatalk Quote Link to comment Share on other sites More sharing options...
Kyle22 Posted April 1, 2016 Share Posted April 1, 2016 I propose a dual purpose board in 800 card form factor. +5 and ground picked up from the card slot, with an additional power connector for XL/XE users. This would simply plug in the 800 with a short PBI cable to the Incognito, or in XL/XE format, the board could be in a case with a PBI cable to the computer. One board for both 800 Incognito and XL/XE. Would there be enough room in the FPGA for a VBXE along with sound chip cores? Quote Link to comment Share on other sites More sharing options...
foft Posted April 1, 2016 Share Posted April 1, 2016 Cool! The pbi/eci+cart could be the Atari's Chameleon... Perhaps include a hdmi and vga port too:) 1 Quote Link to comment Share on other sites More sharing options...
electrotrains Posted April 1, 2016 Author Share Posted April 1, 2016 (edited) Cool! The pbi/eci+cart could be the Atari's Chameleon... Perhaps include a hdmi and vga port too:) Hey I don't think I actually committed to building such a thing! EDIT - though I am tempted. Edited April 1, 2016 by electrotrains 4 Quote Link to comment Share on other sites More sharing options...
bugs Posted April 2, 2016 Share Posted April 2, 2016 Wow...from a dual pokey to a new Atari in under 24hrs. ....award winning feature creep lol Sent from my SM-G920W8 using Tapatalk 3 Quote Link to comment Share on other sites More sharing options...
Defender II Posted April 2, 2016 Share Posted April 2, 2016 Cool! The pbi/eci+cart could be the Atari's Chameleon... Perhaps include a hdmi and vga port too:) Hey I don't think I actually committed to building such a thing! EDIT - though I am tempted. OK, put me down for one for now, maybe two. 2 Quote Link to comment Share on other sites More sharing options...
pazuzu72 Posted September 27, 2019 Share Posted September 27, 2019 On 4/1/2016 at 5:58 PM, electrotrains said: The need for the low pass filter (2 resistors + 2 caps) and headphone jack would make it a pretty messy addition to the board as it stands, which is why I haven't posted the firmware or source for this. Also, although there are spare pins on the FPGA, they are not brought out to a header. Of course someone could always redesign the PCB a bit, and add an audio jack to the board. Then there could be an option on the boot menu to enable dual pokey mode... or SID mode... or.... But I think that it would be better still to make a PBI/ECI+Cart version of the ultimate cart, then the pokeys could live at their normal location. Plus it could act as a RAM expansion too. SD Multicart + 1 Meg RAM + Dual pokey all one one board - that would be a nice thing! Hi, but is the firmware for this project working? I could redo the pcb with the addition of the low pass filter and the headphone jack if that's ok with you. It would be really cool!!!!!!!! 1 Quote Link to comment Share on other sites More sharing options...
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