BitCruncher
Offline
Virginia, US

Hey,

I decided to make a separate thread for this.

So, for those of you who saw the parent thread, you know that I'm into electronics. I'm looking into starting an electronics business and my start-up product was supposed to be this 8-bit video game console that I designed a few summers ago, however, I haven't secured a market for it yet, so, it's just collecting dust on my workbench.

I do plan to get some videos up soon. So far I have written Tetris for it. If you're wondering, the language is assembly.

rvan wrote:
BitCruncher wrote:

You should check out the 8-bit console I built recently.

This looks quite interesting.  I would enjoy reading a detailed write-up if you are planning on making one.  I assume you are storing sprite data on the EEPROM and that this is copied to the Propeller's internal RAM on boot?  If so, is the Z80 involved in this process, or does the Propeller access the EEPROM directly?  Also, does your Cartridge ROM also contain your bootloader, or do you have a separate boot ROM?  I am aware this is off-topic for this thread, so you may wish to start a separate thread about this project.

Well, I was planning on doing a write-up for it when I got a software team together, but that hasn't happened yet, so...

It's just as you say; the sprite data is stored on the EEPROM and it is loaded to the Prop on system start-up. During this process, not only is the Z80 involved in the process, but it's doing all the work; The Prop does nothing as it's just a memory device in the system. The bootloader is on a separate ROM.

rvan
Offline

Thanks for your answers.  I look forward to reading your full write-up.  I have looked at a number of Z80 systems, both commercial kitsets and hobbyist builds, with eventual plans to building one myself.  What sets your design apart is the use of the Propeller as the GPU.  I'm not especially well-versed in Z80 graphics architecture (other than the Game Boy's, which I am passingly familiar with), but I would like to know about the interface between the Z80 and the Propeller.  Does the Z80 see the Propeller purely as a memory-mapped peripheral?

As for selling this as a commercial product (if you are still trying to), I think you are in for a hard task. Projects like this are mostly of interest to hobbyists (like ourselves) who like to build things rather than buy them, although you might have some success selling this as a kitset.  There are a number of kitsets out there for the Z80, but I have not seen many targeted towards video games as opposed to general-purpose microcomputer systems (although I haven't been looking for them specifically).  On the other hand, there are many, many video game console kitsets that are not specifically Z80-based.  This means that you are entering a more-or-less saturated market and will have to come up with a unique selling point.

Jazzmarazz
Offline
Michigan

Same question here. I had a scheme drawn of something similar based on the 68000 rather than a z80, but had to drop it for more pressing things. We should talk.

BitCruncher
Offline
Virginia, US
rvan wrote:

Thanks for your answers.  I look forward to reading your full write-up.  I have looked at a number of Z80 systems, both commercial kitsets and hobbyist builds, with eventual plans to building one myself.  What sets your design apart is the use of the Propeller as the GPU.  I'm not especially well-versed in Z80 graphics architecture (other than the Game Boy's, which I am passingly familiar with), but I would like to know about the interface between the Z80 and the Propeller.  Does the Z80 see the Propeller purely as a memory-mapped peripheral?

As for selling this as a commercial product (if you are still trying to), I think you are in for a hard task. Projects like this are mostly of interest to hobbyists (like ourselves) who like to build things rather than buy them, although you might have some success selling this as a kitset.  There are a number of kitsets out there for the Z80, but I have not seen many targeted towards video games as opposed to general-purpose microcomputer systems (although I haven't been looking for them specifically).  On the other hand, there are many, many video game console kitsets that are not specifically Z80-based.  This means that you are entering a more-or-less saturated market and will have to come up with a unique selling point.

The Propeller from the Z80's point-of-view is nothing more than a memory-mapped video adapter; it sits beside RAM and ROM on the map so accessing it is not a problem. The general architecture of the system is actually more similar to the NES. It's all tile-mapped graphics with a system palette. Writing games for this is surprisingly simple if you're comfortable with assembly and even if you're not, learning the language is not that difficult.

As for selling this...yeah at this stage, I realize that what I'm trying to do is not going to be easy. I coming to grips with the possibility that I may not be as good at coming up with good ideas as I thought. I'm considering going into a partnership electronics venture, and I'll post a thread on that too.

BitCruncher
Offline
Virginia, US
Jazzmarazz wrote:

Same question here. I had a scheme drawn of something similar based on the 68000 rather than a z80, but had to drop it for more pressing things. We should talk.

Sure, definitely. Would it be possible for you to send me your scheme?

cTrix
Offline
Australia
BitCruncher wrote:

Writing games for this is surprisingly simple if you're comfortable with assembly and even if you're not, learning the language is not that difficult.  As for selling this...yeah at this stage, I realize that what I'm trying to do is not going to be easy. I coming to grips with the possibility that I may not be as good at coming up with good ideas as I thought. I'm considering going into a partnership electronics venture, and I'll post a thread on that too.

G'day BitCruncher.   Firstly - congratulations on your development so far!  And for having the vision of tackling something that sits in a pretty daunting target market.  You have my support - as long as there is something unique sound wise, I'd consider buying one (depending on price point and available example code).

I'm looking at the kinds of things I've bought and why - if you peal away the old stuff (C64, Spectravideos, Amigas, Microbee, Vectrex and many Consoles) the "new" 8-bit (ish) devices I have include the C64DTV (for it's extended graphics modes / hack-ability / demoscene support) the MiniMig (for portability and curiosity) and a Familcon clone handheld for it's slightly whacky audio implementation.

At the moment your preview specs the sound as "Sound - Monaural stereo".  ???  (edit: can you expand on this?)

Audio wise it would be great if it had a basic little audio chip.  Something a step up from DMG or C64.... my recommendation would be 6 full-noterange pulse/square/tri/sine/noise channels and 2 x 4 bit PCM channels (all with envelopes) .  Have those split into 2 x LPF / HPF filters so 4 channels are locked to a filter each.  Chip music wise, those specs look like a fun limitation to work with and have more flexibility than something like a Gameboy but keeps the simplicity without hitting the chaos of having to understand something like the SID chip (and it's variants) or the complexity of FM.  Filters would just make it pop out for chip musicians (bit of a buzz word).   

I'm not if you'd be prepared to add something like this to your build...  but it would bring some iconically "expanded 8bit" sound.  I say "Expanded" because a lot of the consoles only had 3 - 5 channels, BUT the arcade machines often had a ton more (as did the NES games with additional chips).  We all secretly like the idea of more channels ;-)

I think the key for drumming up curiosity from chip musician scene is to actually make sure it ships with a usable tracker tool.  Something using a similar system to LSDJ / piggy - even if it's a simple open-source version 1.  Most people will want to buy it and use it "out of the box" as a music tool.  I don't know many chip musicians who would buy a modern 8 bit computer clone if it didn't have audio features that put it ahead of their Gameboy / C64 / NES.  Of course, the final failsafe for chip musicians is to also add (and I think this has been mentioned) a MIDI option - maybe as an additional cable - so you can play the notes directly.  Again, if it was a 6-voice synth with 2 basic PCM channels (maybe write a simple host programm that can load up some sample banks too)... then you'd have something that would look good from a lot of angles.

Certainly a tricky mission to embark on... but that's my take on what would interest me from a modern 8-bit machine.  As an aside, I'd probably never play a game on it... but I'm not a gamer, I'm a musician / demoscener.  That's what I use all my consoles for.

Last edited by cTrix (May 27, 2014 1:48 am)

BitCruncher
Offline
Virginia, US
cTrix wrote:
BitCruncher wrote:

Writing games for this is surprisingly simple if you're comfortable with assembly and even if you're not, learning the language is not that difficult.  As for selling this...yeah at this stage, I realize that what I'm trying to do is not going to be easy. I coming to grips with the possibility that I may not be as good at coming up with good ideas as I thought. I'm considering going into a partnership electronics venture, and I'll post a thread on that too.

G'day BitCruncher.   Firstly - congratulations on your development so far!  And for having the vision of tackling something that sits in a pretty daunting target market.  You have my support - as long as there is something unique sound wise, I'd consider buying one (depending on price point and available example code).

I'm looking at the kinds of things I've bought and why - if you peal away the old stuff (C64, Spectravideos, Amigas, Microbee, Vectrex and many Consoles) the "new" 8-bit (ish) devices I have include the C64DTV (for it's extended graphics modes / hack-ability / demoscene support) the MiniMig (for portability and curiosity) and a Familcon clone handheld for it's slightly whacky audio implementation.

At the moment your preview specs the sound as "Sound - Monaural stereo".  ???  (edit: can you expand on this?)

Audio wise it would be great if it had a basic little audio chip.  Something a step up from DMG or C64.... my recommendation would be 6 full-noterange pulse/square/tri/sine/noise channels and 2 x 4 bit PCM channels (all with envelopes) .  Have those split into 2 x LPF / HPF filters so 4 channels are locked to a filter each.  Chip music wise, those specs look like a fun limitation to work with and have more flexibility than something like a Gameboy but keeps the simplicity without hitting the chaos of having to understand something like the SID chip (and it's variants) or the complexity of FM.  Filters would just make it pop out for chip musicians (bit of a buzz word).   

I'm not if you'd be prepared to add something like this to your build...  but it would bring some iconically "expanded 8bit" sound.  I say "Expanded" because a lot of the consoles only had 3 - 5 channels, BUT the arcade machines often had a ton more (as did the NES games with additional chips).  We all secretly like the idea of more channels ;-)

I think the key for drumming up curiosity from chip musician scene is to actually make sure it ships with a usable tracker tool.  Something using a similar system to LSDJ / piggy - even if it's a simple open-source version 1.  Most people will want to buy it and use it "out of the box" as a music tool.  I don't know many chip musicians who would buy a modern 8 bit computer clone if it didn't have audio features that put it ahead of their Gameboy / C64 / NES.  Of course, the final failsafe for chip musicians is to also add (and I think this has been mentioned) a MIDI option - maybe as an additional cable - so you can play the notes directly.  Again, if it was a 6-voice synth with 2 basic PCM channels (maybe write a simple host programm that can load up some sample banks too)... then you'd have something that would look good from a lot of angles.

Certainly a tricky mission to embark on... but that's my take on what would interest me from a modern 8-bit machine.  As an aside, I'd probably never play a game on it... but I'm not a gamer, I'm a musician / demoscener.  That's what I use all my consoles for.

Thank you for your interest and I really appreciate the input and the suggestions; it helps when people in the target market give feedback for me to go on.

Addressing the sound. As you are most likely well aware, true stereo is accomplished by establishing two independent audio channels and so, a tone can be played on the left channel without being heard on the right. My system produces a single channel of audio which can be heard by both ears (hence "stereo"), however, there is no right or left channel (therefore "monaural").

As far as producing professional chiptune on the system goes, I think the biggest problem is that the sound chip is also the graphics chip. Ultimately what I would have to do is gut out all of the modules that don't pertain to sound production. This is why I thought to design a dedicated chiptune instrument. Check out the thread link in first post to see the idea.

Thank you again for your support. I'll definitely keep you guys posted on how development goes.

PROTODOME
Offline
UK

I know you're using the chip for gfx as well, but couldn't you spare a few pins for outputting PWM audio? It'd be stupid easy to have a bunch of preprogrammed waveforms (including a random noise generator) and the ability to switch between those and samples at runtime. That way you'd have a couple of GB-wav-like (yes I know it's PCM) channels, which would be really fun to write for.

Failing that, you could always add a dedicated PSG chip, keep everyone happy.

Last edited by PROTODOME (May 27, 2014 5:31 pm)

BitCruncher
Offline
Virginia, US
PROTODOME wrote:

I know you're using the chip for gfx as well, but couldn't you spare a few pins for outputting PWM audio? It'd be stupid easy to have a bunch of preprogrammed waveforms (including a random noise generator) and the ability to switch between those and samples at runtime. That way you'd have a couple of GB-wav-like (yes I know it's PCM) channels, which would be really fun to write for.

Failing that, you could always add a dedicated PSG chip, keep everyone happy.

I wish I could; unfortunately, I have absolutely no room left for anything else. I already have the CPU taking up 92% and the rest is video output and memory control logic. If I see more interest in the system, maybe I'll do a complete redesign. Plus, as stated in the previous post, If you guys want a musical instrument, it would probably make more sense to just make a dedicated instrument and not a video game console.