What would it take to get some of Dennis 6502 + Prop boards made?

potatohead

I flat out want one, and I know others want one. I don't have the skill or the means to build one of my own right now either.

Looks like a through hole design, meaning populating them would be no big deal for those of us with moderate soldering skill, and or gear.

Where does the cost breakdown make sense? 5, 10, 20? I'll chip some $$ in, anyone else?

As an alternative, would that project fit on a breadboard? If so, what size?

I didn't see a layout in the project documentation. Is this something that is too difficult for a side project, or what?

www.parallax.com/tabid/708/Default.aspx

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Post Edited (potatohead) : 11/28/2009 6:11:42 PM GMT

Leon

Where are the details of this project?

Leon

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potatohead

www.parallax.com/tabid/708/Default.aspx

Sorry Leon. Thanks for catching that missing link.

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Forrest

If this gets Potatohead closer to making a portable Atari 2600 (or my dream - a portable Atari 8-bit computer), I would be interested in a board also.

Lots of discussion on a Atari 2600 clone here http://www.atariage.com/forums/topic/151276-a-brand-new-atari-2600-clone-project/

potatohead

Yeah, that thread is exactly what triggered my query. So, I'm hacking at FREEWAY, and other retro things, thinking along those lines, and that project has nagged at me since he finished it.

Looking at the work required for full on emulation, and the work I think programming this board would take, it's kind of a no brainer, and the result would likely be more robust.

Plus, that kind of thing is just fun.

Would it fit on the PPDB breadboard? I'm asking because I know others here could asses that quickly. It would take me hooking it up, wire by wire to sort that out. Would be nice to know it's possible before I gladly go down that road!

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Post Edited (potatohead) : 11/28/2009 6:35:44 PM GMT

Leon

It would be quite easy to design a PCB for it, it only uses five chips plus a couple of regulators.

Leon

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Post Edited (Leon) : 11/28/2009 7:03:42 PM GMT

potatohead

Leon, will that design fit on the PPDB? I just need to know it will fit, and will gladly go and do the work from there. (hints welcome though, make no mistake)

If so, I think I'm going to do it and get it running. A software demo or two shown in the right places will generate some interest.

PM me about board layout. This might make sense in the near future.

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Leon

I don't know, I never use solderless breadboards. I'd much rather design a PCB and make it at home, or get one made.

Leon

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mikediv

I agree I Want one as well if you guys are willing to help me figure out how to do this I would be willing to pay for and order the initial run of boards I just have never done this before so I would need to know how to send the Gerber files? and even get them and what company you guys think would be the best , of course if this is all OK with the(Dennis Ferron) let me know I am in either way

Leon

Mikediv:

I've started designing a board for this project. Here is the schematic so far:

www.leonheller.com/Propeller/Prop-6502/Prop-6502(Page1).pdf

PH wants to build it first on the PPDB, and then get some PCBs made if it works OK. If you want to try it out first, I'll let you have the Gerbers etc. when it's finished, and you can get a prototype board made.

Leon

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Dr_Acula

Re mikediv and gerbers, see this Instructable towards the end www.instructables.com/id/Professional-PCBs-almost-cheaper-than-making-them-/

Personally, I'd be looking at buying a few breadboards first - indeed a couple of breadboards would be cheaper than getting PCBs made. Then you can experiment and test things out first. eg - what are the merits of TV vs VGA, what storage media is best etc?

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potatohead

Yeah, that's where I'm headed too. The design Dennis posted is simple enough that I think I can get it breadboarded without blowing stuff up. Deffo need SD card.

IMHO, TV will be fine, but perhaps with a different resistor set and or code to get 16 grey scales and hues.

I'm going to hack on this, but need to finish FREEWAY and some 80 column text polish ups first. The other thread reference triggered this query. Thought it would take some time to sort out anyway.

One task is to source the other chips. I've got a 6502, but have no idea where to order the others without paying a ton.

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Dr_Acula

If you have the chips this ought to only take a few hours to breadboard. Sounds a lot of fun. Re "One task is to source the other chips. I've got a 6502, but have no idea where to order the others without paying a ton."

There are only 5 chips, right? The ram chip would be $4 or so. The logic chips 40c each. Shipping would be the biggest cost unless you have a local supplier.

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VIRAND

Why give up on emulating a 6502?
Z-80 emulation is amazing.
6502 is underwhelming... STRICTLY 8-bit, with the fewest instructions and registers.

You can probably reverse engineer Stella.exe (DOS Atari 2600 emulator). I've got that somewhere on a floppy.

Leon

The 6502 can often run code very fast, because of the zero page addressing. IIRC, the 6502 at 1 MHz was just as fast as the 4 MHz Z80, because the clock was divided by 4 on the Z80.

Leon

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potatohead

Yes, that's it exactly. The number of Propeller instructions that can be executed in the time consumed by the shorter 6502 instructions isn't all that high. My early experiences show 6502 code running at speed is possible, but that's before the memory and state trapping and communication are part of the picture. Some pretty sharp people, who grok that complexity, have come up short on compute time. Not saying it isn't possible, but it's not probable without a ton of work.

A VCS doesn't contain much, but what is there has very high complexity, and lots of cycle exact timing dependencies. The number of man hours on Stella is huge, and the emulation is nothing short of amazing. I've the recent build on my machine, and it's killer. Reversing it might be handy to learn some specific things about TIA, but that's it. How a TIA gets done on Propeller will be considerably different, IMHO.

Eric has contributed a 6502 core, and that's cool and much appreciated. It needs a debug, and that's going to take some time.

Time that I think I would rather spend to see whether or not a TIA can be done on the Prop in real time. That's just as big of an effort as debugging the 6502 is. Perhaps a circuit like this could be used as the basis for a Propeller running as a 6502 sometime in the future using that core or some variation of it, like the other multi-prop projects show is possible. The TIA is necessary no matter what, and this direction gets that on the table in a time frame that makes sense.

I proposed a trade on the AA board, wondering whether or not somebody in that community might like a start on Propeller. (the more the merrier)

If there are no takers, I will extend it here, preferring to get some hardware into eager hands, over paying for shipping and handling.

(for now back on FREEWAY and text)

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Post Edited (potatohead) : 11/29/2009 7:48:22 PM GMT

Forrest

Potatohead wants to emulate an Atari 2600, which depends on instruction cycle accuracy to generate the video and audio. The 2600 used a 6507 at 1.19 MHz and only 128 bytes of RAM with no frame buffer.

potatohead

I think this design could do other things too, like an Apple ][noparse][[/noparse].

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mikediv

Awesome thank you guys. I have always had a fondness for the 6502 it was the very first CPU I used in class ASM of course then we moved the 6800 the 6502 was so much easier for me to learn back then can't wait to get a board working
I was wondering is there a an Apple, Atari emulator in the future?

potatohead

I've placed an order for two sets of all the core components, but for those 64kx8 SRAM chips. Many of the places I tried had either a stiff minimum, didn't have the full compliment of components, or were out of stock... Anyone have any ideas on those SRAMS? I'm not really all that experienced on sourcing things like this...

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Cluso99

potatoehead: You could use a 128Kx8 or 512Kx8 55ns sram if you can get them without volume. BUT they are 32pins.

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Links to other interesting threads:

· Home of the MultiBladeProps: TriBlade,·RamBlade,·SixBlade, website
· Single Board Computer:·3 Propeller ICs·and a·TriBladeProp board (ZiCog Z80 Emulator)
· Prop Tools under Development or Completed (Index)
· Emulators: CPUs Z80 etc; Micros Altair etc;· Terminals·VT100 etc; (Index) ZiCog (Z80) , MoCog (6809)
· Search the Propeller forums·(uses advanced Google search)
My cruising website is: ·www.bluemagic.biz·· MultiBladeProp is: www.bluemagic.biz/cluso.htm

potatohead

I fear that package style won't work out on the PPDB breadboard. Need to do some planning with sockets this weekend. I find it hard to visualize the circuit on those things...

Edit...

Well, one source came up with $18.00, including shipping. I think I'm gonna just do that, and deal. That way it's a 1:1 match with the project documents, keeping things as simple as possible for me.

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Post Edited (potatohead) : 12/5/2009 9:34:00 AM GMT

Dr_Acula

Heater might be able to answer this, but where are we up to with the 6502 emulation? I know the 8080 series off the top of my head (right up to pentiums etc) but I don't know the 65xx series so well.

As a general principle, emulating these old micros really is just a matter of getting some I/O working (trapping I/O calls via spin) and a decent amount of memory - eg 64k. The triblade and dracblade can do all the hardware aspects.

Unless I am mistaken, only one person has managed to actually write the code to emulate all a micro's instructions, and that is heater.

And even when a micro has had all its instructions replicated, there is the operating system to consider - whatever that may be. heater and cluso are the experts on that. I am very familiar with the internal O/S of the 8080 series but know nothing about the 65 series. But what I could contribute is the hardware side - ie a board that has a keyboard, vga, mass storage emulating a hard disk, enough ram with block I/O etc.

If you want a 6502 emulation, I'm pretty sure you don't need the actual 6502 chip. But it would be a very useful stepping stone to that point to be able to do this with a real chip, plus the necessary memory etc.

When you say $18, is that for a ram chip? That seems awful high - 512k ram from future electronics is only $3.18 (Jameco $5.95). 2^16 is 64k and 2^19 is 512k so you can always just use A0-A15 and tie A16-18 to ground. ( the dracblade is only using 64k for the moment, though it can do 512k if you want). The AS6C4008 is a nice chip in that it can run 3V to 5V, it is fast and it has more than enough memory. It is also versatile, I'm using it for the N8VEM with a real Z80, on the triblade and the dracblade. It is 'backwards compatible' if you like.

I suppose you could always just build a board to replicate the original circuit exactly. Looking at it though I bet you would want to add other things on fairly soon. Makes it harder thinking about the 'perfect' board for this, hence it may be still better to breadboard it first.

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Post Edited (Dr_Acula) : 12/5/2009 10:33:53 AM GMT

Cluso99

The 6502 emulation will not be the main issue. The real issue is that these computers (Apple//e, Commodore, etc) used the RAM as the video ram as well. That is an issue for external ram. IIRC the Apple //e used a 6845 for the video chip which interrupted the 6502 when it needed video access.

So our issue will be trapping the video RAM and duplicating it in hub. Next will be the problem that Apple used adjacent pixels to form color.

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Links to other interesting threads:

· Home of the MultiBladeProps: TriBlade,·RamBlade,·SixBlade, website
· Single Board Computer:·3 Propeller ICs·and a·TriBladeProp board (ZiCog Z80 Emulator)
· Prop Tools under Development or Completed (Index)
· Emulators: CPUs Z80 etc; Micros Altair etc;· Terminals·VT100 etc; (Index) ZiCog (Z80) , MoCog (6809)
· Search the Propeller forums·(uses advanced Google search)
My cruising website is: ·www.bluemagic.biz·· MultiBladeProp is: www.bluemagic.biz/cluso.htm

Dr_Acula

Aaargh! Video ram will be tricky. Would the triblade be fast enough? There are quite a number of instructions just to get one byte in and out of ram. What is the minimum screen resolution? Hmm - even 640x480x16 colors is 614 kilobytes. How on earth did they get video working on those early computers? (from memory the text was 'blocky'. Maybe that was the secret?)

Could we redesign a ram circuit so it read out ram sequentially in a rapid manner suitable for a video driver circuit? Crazy idea here, but maybe just fill all the ram with values and read it out with a counter incrementing the address bytes in discrete logic and feeding a D/A using an 8 bit R/2R circuit. Old school I know, but it would only be a few chips.

Or a more cunning circuit taking the 6502 graphics commands and translating them into existing spin code drivers for video.

Roll on the Prop II...

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Post Edited (Dr_Acula) : 12/5/2009 10:42:10 AM GMT

Cluso99

Yes. Many computers only had 32 or 40 characters x 16 lines. IIRC the Apple //e soon had 80x25. An addin card made by Ozzie Harry Zofarry was sold extensively. Later it had a couple of bits for color. But only the 256 characters were stored and I think a character generator rom was used to lookup the pixels.

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Links to other interesting threads:

· Home of the MultiBladeProps: TriBlade,·RamBlade,·SixBlade, website
· Single Board Computer:·3 Propeller ICs·and a·TriBladeProp board (ZiCog Z80 Emulator)
· Prop Tools under Development or Completed (Index)
· Emulators: CPUs Z80 etc; Micros Altair etc;· Terminals·VT100 etc; (Index) ZiCog (Z80) , MoCog (6809)
· Search the Propeller forums·(uses advanced Google search)
My cruising website is: ·www.bluemagic.biz·· MultiBladeProp is: www.bluemagic.biz/cluso.htm

Dr_Acula

"I think a character generator rom was used to lookup the pixels."

Hmm - if that is the cunning trick they used maybe that is the way to replicate it? We need an expert 6502 person here.

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Sapieha

Dr_Acula


Hi You not need expert on 6502 ... it is relatively simple CPU ...
BUT to that You need expert on 6845 .... It was very clever chip and still simple

Regards
ChJ

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Nothing is impossible, there are only different degrees of difficulty.
For every stupid question there is at least one intelligent answer.
Don't guess - ask instead.
If you don't ask you won't know.
If your gonna construct something, make it·as simple as·possible yet as versatile as posible.


Sapieha

Ale

Dr Acula:

If you mirror the video RAM with what a propeller has in HUB you can read that external SRAM, write to both external SRAM and HUB RAM and you avoid all the complications of interleaved access, or so I think. This is the method I used in the pPropQL and It works ok.

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Visit some of my articles at Propeller Wiki:
MATH on the propeller propeller.wikispaces.com/MATH
pPropQL: propeller.wikispaces.com/pPropQL
pPropQL020: propeller.wikispaces.com/pPropQL020
OMU for the pPropQL/020 propeller.wikispaces.com/OMU

Dr_Acula

Thanks Sapieha and Ale.

6845. Ok.

en.wikipedia.org/wiki/Motorola_6845

14 bits and 5bits. I'm trying to work out what that means. It is 512k which is ball park for what we are building. The 'tricks' section is interesting.

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Sapieha

Hi Dr_Acula


As 6845 used or buffer to text moed ... Standard ASCI that was translated to pixel patern by ROM.
You can entirely use Propellers TV,VGA video TEXT video modes.
Yours only concern will be to share RAM portion taht 6502 will use to buffer it.
And simply read it and display by Propellers VIDEO TEXT modes.
It was not much tcht RAM to share only 2-4 KB for text modes.

Regards
ChJ



Ps Character ROM to TEXT modes was not part of RAM adres area of 6502.

It has dedicated area directly in 6845 Video chip that ROM is Coded for Patern by ROW-Column not sure now ... it was longht time I worked with it.

BUT it was from in range ROW=8-16, Column for pixels = 5=10 ..... but that is not exact ..... Not mind correctly

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Nothing is impossible, there are only different degrees of difficulty.
For every stupid question there is at least one intelligent answer.
Don't guess - ask instead.
If you don't ask you won't know.
If your gonna construct something, make it·as simple as·possible yet as versatile as posible.


Sapieha

Post Edited (Sapieha) : 12/5/2009 1:49:52 PM GMT