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Is this an unusual hobby (making useless schematic diagrams)
Posted: Fri Dec 23, 2011 9:38 pm
by psycopathicteen
I don't know how it all started, but I have this weird hobby of designing schematic diagrams and technical documents for systems I am not going to build anyway since I don't have the money to actually build them.
Does it sound like I have way too much free time on my hands, or does it sound like something you guys do in your spare time when your board?
Posted: Sat Dec 24, 2011 7:32 am
by ccovell
It's what I did when I was 13... designing things like the "Debug Booster", a TurboBooster-shaped device for the Turbografx that had switches connected to every pin on the TG expansion board, and it allowed game hacking, modification, etc. All on paper only, of course.
I also remember designing a Turbografx-III, something more powerful than the SuperGrafx and it took a dual-layered HuCard (imagine two Street Fighter II' PCE cards glued one on top of the other) because of its immense power.
It's not a bad hobby. When you're 13.
Posted: Sat Dec 24, 2011 1:09 pm
by kyuusaku
Sounds kinda like me. I mostly reimplement or document existing systems through schematics, but sometimes I have an urge to work stuff like a '70s style display controller using minimal discrete chips just to see what I could have come up with were I alive then. Over time the projects have piled up and some of the more recent ideas are becoming grandiose, plus I do the same with software, so for example lately I've been putting hours into designing a modern operating system which I'm sure is crazy. I guess it's all part of the learning process.
I think if you like designing systems then cool, it's only pointless if you abandon your ideas because of other people. Implement one in a FPGA then keep improving on it. For a while I was thinking about an original arcade system, something like the Cave hardware which is still successful despite being 2D. I gave up on that idea but I took some things away from it.
Posted: Sat Dec 24, 2011 1:23 pm
by Shiru
To implement something in FPGA you first need to get a devboard, and they are rather costly.
I also design random digital schematics sometimes, either modern MCU-based, or something retro, and never implement them in reality, because I don't have money for this. It is not that useless, as it allows to learn something new.
Re: Is this an unusual hobby (making useless schematic diagr
Posted: Sat Dec 24, 2011 3:21 pm
by zzo38
I used to do that kind of things too, actually. Not much today, but sometimes I still might do so, in case eventually later I might be able to build it, or post for anyone else to build if they like to do so
Posted: Sat Dec 24, 2011 3:22 pm
by psycopathicteen
Today I have been writing a document for a video chip that is sort've like a successor to the Genesis's VDP with double the VRAM bandwidth.
Code: Select all
My VDP runs at 13.5 Mhz, with 858 cycles per line, 262 lines per frame. The pixel clock is exactly half that at 6.75 Mhz and 429 pixels per line, with 320 pixels (640 cycles) of them being onscreen, and 109 pixels (218 cycles) during Hblank.
There are four background modes
mode # BG1 BG2 BG3 BG4
00 yes yes yes yes
01 affine yes no yes
10 yes affine yes no
11 affine affine no no
VRAM access pattern:
active display:
cycles 0-639 backgrounds (see below)
H-blank:
cycles 640-839 sprites (see below)
cycles 840-855 backgrounds left-most tiles
cycles 856-857 unused
backgrounds:
bg1 offset-per-tile or bg1 affine pixel
bg2 offset-per-tile or bg2 affine pixel
bg3 offset-per-tile or bg1 affine pixel
bg4 offset-per-tile or bg2 affine pixel
bg1 attributes or bg1 affine pixel
bg2 attributes or bg2 affine pixel
bg3 attributes or bg1 affine pixel
bg4 attributes or bg2 affine pixel
bg1 pixels 0-3 or bg1 affine pixel
bg2 pixels 0-3 or bg2 affine pixel
bg3 pixels 0-3 or bg1 affine pixel
bg4 pixels 0-3 or bg2 affine pixel
bg1 pixels 4-7 or bg1 affine pixel
bg2 pixels 4-7 or bg2 affine pixel
bg3 pixels 4-7 or bg1 affine pixel
bg4 pixels 4-7 or bg2 affine pixel
When it accesses affine pixels, the low 8-bit data bus accesses the tile attributes while the high 8-bit data bus accesses the pixel.
sprites:
normal sprites 4 pixels per access
affine sprites 1 pixel per access (choses 1 of 4 pixels, the other 3 pixels are thrown out)
Posted: Mon Dec 26, 2011 4:54 am
by TmEE
I've been putting a lot of energy into this machine :
http://www.fileden.com/files/2008/4/21/ ... tGlory.png
It is also one of the reasons I no longer do console modifications and why I have not been very active in the MD scene
Posted: Wed Dec 28, 2011 11:02 am
by kevtris
Shiru wrote:To implement something in FPGA you first need to get a devboard, and they are rather costly.
I also design random digital schematics sometimes, either modern MCU-based, or something retro, and never implement them in reality, because I don't have money for this. It is not that useless, as it allows to learn something new.
Not any more. FPGA dev boards are relatively cheap these days. For under 200 bucks you can get a very decent one that has RAM, flash, video, audio, SD card, ethernet (I think) and other doo-dads.
I highly recommend using Altera parts and staying away from Xilinx, simply because Altera's quartus software is so much nicer/better than webpack ise. This is personal pref of course, but I've been using quartus for 7 years or so now.
For a dev board, the DE series by terasic is very nice and cheap.
http://www.terasic.com.tw/cgi-bin/page/ ... o=53&No=83
$150 (or $125 if you get the academic discount, which I hear is easy to get) for a really nice board that is more than enough to do an FPGA NES and then some on.
That board has SRAM, SRAM, flash, VGA, audio and tons of other goodies.
The DE1 level of FPGA'age is good enough to implement all the FPGA consoles I've done so far (8 or 9) and I have yet to run out of resources.
Shameless plug: Since I finished the FPGA NES, I have gone on to implement these ones too:
* SMS/GG
* Colecovision
* Atari 2600
* Intellivision + Intellivoice + ECS
* Odyssey^2 + the voice
* Supervision
* adventure vision
* Mandelbrot renderer (I have code released for that in verilog)
All of those consoles are 100% finished and run every game made.
Currently I am working on SPC700 and hope to start on SNES some time.
Posted: Wed Dec 28, 2011 11:57 am
by infiniteneslives
kevtris wrote:
Shameless plug: Since I finished the FPGA NES, I have gone on to implement these ones too:
* SMS/GG
* Colecovision
* Atari 2600
* Intellivision + Intellivoice + ECS
* Odyssey^2 + the voice
* Supervision
* adventure vision
* Mandelbrot renderer (I have code released for that in verilog)
All of those consoles are 100% finished and run every game made.
Currently I am working on SPC700 and hope to start on SNES some time.
Pure awesomeness...
Any thoughts of when, how, or if you plan on releasing these to the public?
Posted: Wed Mar 07, 2012 6:16 pm
by SkinnyV
Can you elaborate more on what were looking at?
BTW, no hobby that teach you something could be described as stupid even if you never build the thing you were working on. Thing and project end up on shelf/garbage years later, knowledge stay forever (or until you get senile
) When I was 8, me and 2 buddy of mine were working on building a time machine. We were doing sketch of the machine and discussing it a lot. It seem though that I was the only one really intending on building it as I remember salvaging junk electronic in the street (remember a watch I found and was very excited about that I was planning on de-assembling and saving the LCD for a time display in the machine
) and also remember feeling so betrayed when one of my 2 friend got confused about me talking about it all the time and picking up stuff for it and told me he wasn't really thinking of building one now but in the future when we are grown up. Upon hearing that terrible confession, I lost no time in luring him in my tele-transporter and fused that Judas with a fruit fly that was in the pod.
I tought of selling the right for the movie but Jeff Goldblum was unavailable at the time
Posted: Wed Mar 07, 2012 7:56 pm
by Karatorian
Not at all strange, as long as you're comfortable being a geek. Heck, just the other day I designed a couple of block diagrams of a mapper I don't intend to build (and one of which was wrong), just to illustrate a discussion.
Posted: Wed Mar 14, 2012 6:00 am
by TmEE
SkinnyV wrote:Can you elaborate more on what were looking at?
Should answer all the questions :
http://vgm.mdscene.net/forum/viewtopic.php?t=165
