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Author Topic: What's the point of the MiniMig?  (Read 12983 times)

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Offline AmiGR

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Re: What's the point of the MiniMig?
« Reply #74 from previous page: November 11, 2007, 03:16:48 PM »
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The 68K processor has already implemented in a FPGA core alongside the Minimig code (see TobiFlex's work), so the biggest barrier to reducing price seems to be the RAM. Would using DRAM rather than SRAM really reduce prices by a significant amount?


Wow, I'll take a look at TobiFlex's work, I was planning on putting a 68k core on the FPGA myself. About the RAM, well, SRAM is generally expensive. If we implement a DRAM controller on the FPGA and getting the timings right, 2MB of EDO DRAM is £2.50-3 in single quantities, at least £2 cheaper than SRAM.

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If you are looking for a seller of the Xilinx XC3S400-4PQG208C within the UK, a quick websearch came up with this result:
http://www.ashlea.co.uk/157.html

At the time of writing this they have thousands in stock:
http://www.ashlea.co.uk/scripts/availability.pl?partID=XC3S400-4PQG208C

I've never used this particular supplier before so I couldn't vouch for their reliability. Why not send them an e-mail for a quote.


Oh, cool. It seems I'll have to go through University to use them, though, they do not appear to be selling to individuals.
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Offline amazing

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Re: What's the point of the MiniMig?
« Reply #75 on: November 11, 2007, 04:24:24 PM »
i dont see the point of beeing expensive
i bough t the a500 in 1987 for around 1400 dmark(yes germany)

if u calculate it it should be around 700 euro

so 300euro for a new (amiga) is rather cheap i think
and it has the nice sdcard in it ..

and i played with wizard66 the game bubble bobble in 2 player mode and it feels like the real thing

a1200 blizzard 68030@50mhz/128mb/slimlinecdrom/os3.9
1x MINIMIG...Arm+mem upgrade---build 3
2x a500 1mb internal+2mb in a supraram kick 1.3
c64_1541 with z80 processor
c64 c aldi model+1541 II
3x vic-20_vic1541
1541 III by j.derogee
 

Offline HenryCase

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Re: What's the point of the MiniMig?
« Reply #76 on: November 11, 2007, 04:26:01 PM »
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AmiGR wrote:
Wow, I'll take a look at TobiFlex's work, I was planning on putting a 68k core on the FPGA myself. About the RAM, well, SRAM is generally expensive. If we implement a DRAM controller on the FPGA and getting the timings right, 2MB of EDO DRAM is £2.50-3 in single quantities, at least £2 cheaper than SRAM.


Well, that's certainly worth doing then (changing to DRAM). Anything we can do to make the Minimig cheaper is worth considering, are there any other areas we could make savings (such as incorporating the PIC functions into the FPGA)?

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AmiGR wrote:
Oh, cool. It seems I'll have to go through University to use them, though, they do not appear to be selling to individuals.


If you do find out what price you can get through your University, can you let us know just in case there are interested parties looking to purchase the chip. I've just e-mailed Ashlea Components to see if they will sell to individuals and if I get a response I'll do the same. I tried to find the specific Xilinx FPGA through RS Components, Maplin and Rapid, no dice. Are there any other UK electronics suppliers we could try?
"OS5 is so fast that only Chuck Norris can use it." AeroMan
 

Offline alexh

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Re: What's the point of the MiniMig?
« Reply #77 on: November 11, 2007, 04:46:18 PM »
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AmiGR wrote:
What are you going on about? There's nothing on the MiniMig that is expensive. The reason they go for $200 is the fact that they're built in single units.

Yes you are correct. That and they are being made by homebrew amateurs and not on mass so there are no discounts on quantities. But that isnt going to change any time soon. So if you were making one in the future (following on from our previous msgs) you'd be doing it in.. *da da* single units.

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You could use a larger FPGA and put most of the peripheral hardware onto that, have it on a BGA package on a tiny PCB and it would cost next to nothing.

A phrase rhyming with "duck cough" comes to mind.

You dont know anything about BOM prices, availability or PCB design, so using phrases like "next to nothing" is just insulting to those who have been trying so hard to bring MiniMig to the masses. If what you said was true, everyone would be doing it, they are not, so you are WRONG!

The main reason no-one has used a BGA chip is because they are impossible to solder without expensive BGA IR flow equipment that no "homebrew" team will ever have.

Before you start cost reducing something that doesnt need cost reducing and redesigning a PCB (something almost certainly beyond your capability) lets try to get some of the MiniMig v1.1 boards made en mass and price savings that way!

If we could find a company/individual ready to stump up the time to talk to the manufacturer and the £2000 deposit required to get a batch of 200+ units made we could reduce the costs to the end customer. The profits from this could be invested to make more boards and future cost downs.

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Offline AmiGR

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Re: What's the point of the MiniMig?
« Reply #78 on: November 11, 2007, 05:24:53 PM »
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You dont know anything about BOM prices or PCB design, so using phrases like "next to nothing" is just insulting to those who have been trying so hard to bring MiniMig to the masses.


Lets see, I have sourced, ordered and paid for all the components on the MiniMig and am well aware of the unit costs. I was not for one second trying to say that everybody else is doing anything wrong, I was and am talking about a mass produced simplified design, as a reason for which the MiniMig is not a waste of time.

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If what you said was true, everyone would be doing it, they are not, so you are WRONG!


This is a young project and people are heading towards the direction of reducing the component count of the board, as another person has already mentioned, someone has already put the 68k into the FPGA as an IP core. The thing is, you probably know as well as I do that what would cost "next to nothing" in mass production would cost the earth or be practically impossible for the numbers we're talking about or, even worse, hand-soldered single units. So, I am not exactly disagreeing with you here, I just do not believe that the fact that the MiniMig is currently made in single units and is expensive means that it's useless or that repairing A500 boards is a better idea.

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The main reason no-one has used a BGA chip is because they are impossible to solder without expensive BGA IR flow equipment that no "homebrew" team will ever have.


Yes, but I was talking about a cheaper, smaller and simpler version. You aren't exactly going to order 200 boards and parts and hand solder them, are you? Obviously, you wouldn't wanna use BGA even for 200, but my point was, there is nothing on the MiniMig that is prohibitively expensive and the design has potential for significant cost saving for, say, an Amiga-in-a-Joystick.

Anyway, the reason I mentioned BGA was not because I had a brainfart and wanted to throw a buzzword. I'm well aware that it would require a more complex PCB. The reason I mentioned BGA was that all 1M-gate Spartan 3 chips are BGA. The thing is, as more hardware would be integrated on the FPGA, the larger number of I/O pins wouldn't really be needed. The ideal candidate for something like that in the Spartan series would be a 3E, which is biased towards more logic on package versus I/O pins but the largest 3E is 500K gates, which I think is not enough for a 68k IP core plus the MiniMig chipset. Depending on the number of pins available versus the number of pins used if the 68k and perhaps the controller gets moved onto the FPGA, you may not have to use a very significant number of BGA IO pins and get away with using a 2 layer board but I may well be very very wrong, I have not checked the Spartan 3 BGA pin-out to see what fan-outs could be used.

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Before you start cost reducing something that doesnt need cost reducing and redesigning a PCB (something almost certainly beyond your capability)


And what makes you think that that's almost certainly beyond my capability? I have designed PCBs and the MiniMig PCB is not exactly the most complex design in the world. I probably would not be the right person to spearhead such an effort, I'm not that experienced with PCB design but again, I'm talking about possibilities, not how "I'd do it better".

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lets try to get some of the MiniMig v1.1 boards made en mass and price savings that way!


I fail to see your point here. You were complaining about the fact that it's expensive and saying that you could fix A500s for less, right? I basically gave you reasons for which working on the MiniMig *is* a good idea and have been talking about the possibilities.

Again, my point is, mass production brings costs down but when mass producing, simplifying the design can bring some quite major savings.

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If we could find a company/individual ready to stump up the time to talk to the manufacturer and the £2000 or so required to get a batch of 200+ units made we could reduce the costs to the end customer. The profits from this could be invested to make more boards and future cost downs.


That I agree on 100%.

Apologies if I sounded like a smart-ass.

Edit: Added a few things as I went along.
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Offline HenryCase

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Re: What's the point of the MiniMig?
« Reply #79 on: November 11, 2007, 06:08:17 PM »
Message for alexh and AmiGR.

Please both stop this willy measuring type of argument, is getting us nowhere.

Reducing the cost of the v1.1 Minimig is clearly worthwhile, I'll go into ways we could feasibily do this in a minute. However, take a look at the comments made on the subject of the Minimig you'll see that a lot of people are waiting for a more powerful and expandable Minimig. Therefore, considering the size of the Amiga market, v1.1 is not going to be hugely mass produced.

Now onto the ways we can reduce Minimig costs. These are:
1. Find the cheapest sources for components and buy in bulk with other Minimig builders.
2. Look at ways the design can be simplified so it requires less money to purchase the components (this would require a PCB redesign too).
3. Look into companies able to do runs of PCBs and supply parts in one kit, buy in bulk.

You may even be able to find companies willing to assemble short runs of Minimigs, which wouldn't necessarily reduce the cost but would open the Minimig market up to Amiga fans not ready to solder units themselves. I appreciate the work of people like wizard who are doing something about this.

How about those of us who go to University, does your University have electronics assembly equipment?
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Offline alexh

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Re: What's the point of the MiniMig?
« Reply #80 on: November 11, 2007, 06:18:56 PM »
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AmiGR wrote:
Quote
alexh wrote:
lets try to get some of the MiniMig v1.1 boards made en mass and price savings that way!

I fail to see your point here. You were complaining about the fact that it's expensive and saying that you could fix A500s for less, right?

If MiniMig's got mass produced at a price competitive with old A500's, then my argument goes away dont you think?

The C64 joystick for example can be picked up everywhere for about £5 or less. I myself have several. The mods can be done to play games from flash very easy. I wouldnt recommend getting a old C64 (or getting one repaired) over a homebrew mod of a C64 joystick in this situation would I?

It is a shame that no-one has organised a "mass buy" on components and sold them on. Everyone is buying them in singles from digikey which isnt helping :(
 

Offline AmiGR

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Re: What's the point of the MiniMig?
« Reply #81 on: November 11, 2007, 06:19:29 PM »
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Message for alexh and AmiGR.

Please both stop this willy measuring type of argument, is getting us nowhere.


Yep, sorry, I fear that I started it by snapping at Alex. Sorry about that.

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How about those of us who go to University, does your University have electronics assembly equipment?


Not much that would really be useful for this.
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Offline AmiGR

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Re: What's the point of the MiniMig?
« Reply #82 on: November 11, 2007, 06:23:06 PM »
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If MiniMig's got mass produced at a price competitive with old A500's, then my argument goes away dont you think?

The C64 joystick for example can be picked up everywhere for about £5 or less. I myself have several. The mods can be done to play games from flash very easy. I wouldnt recommend getting a old C64 (or getting one repaired) over a homebrew mod of a C64 joystick in this situation would I?


Well, the thing is, it has the potential to become rather cheap, even though it currently isn't, that's my whole point. Really sorry I snapped at you, earlier, starting an argument. 100% my fault.

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It is a shame that no-one has organised a "mass buy" on components and sold them on. Everyone is buying them in singles which isnt helping.


Yeah.
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Offline alexh

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Re: What's the point of the MiniMig?
« Reply #83 on: November 11, 2007, 06:37:06 PM »
One of the "points" of MiniMig doesnt seem to be getting exploited.

I am suprised that there has been no ports of other "opensource hardware" to a MiniMig board yet? Tobiflex's Amstrad CPC core or Mike-C's VIC 20 or Sinclair ZX Spectrum
 

Offline HenryCase

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Re: What's the point of the MiniMig?
« Reply #84 on: November 11, 2007, 07:03:42 PM »
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AmiGR wrote:
Yep, sorry, I fear that I started it by snapping at Alex. Sorry about that.


Well I respect anyone who has the cohones to admit when they've done something wrong, so no worries.

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alexh wrote:
I am suprised that there has been no ports of other "opensource hardware" to a MiniMig board yet?


It is a shame. How easy would it be to port one of those examples mentioned? I mean is the h/w they normally run on fairly similar?
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Offline AJCopland

Re: What's the point of the MiniMig?
« Reply #85 on: November 11, 2007, 07:37:57 PM »
Oh they will, indeed doing things like that is one of the cores reasons why I like the idea of the MiniMig.

However thats at the "running" stage and I'm still waiting for parts so that I can get to the "walking" stage. I.e. a complete and functioning MiniMig v1.1

Quote

alexh wrote:
One of the "points" of MiniMig doesnt seem to be getting exploited.

I am suprised that there has been no ports of other "opensource hardware" to a MiniMig board yet? Tobiflex's Amstrad CPC core or Mike-C's VIC 20 or Sinclair ZX Spectrum
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Offline alexh

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Re: What's the point of the MiniMig?
« Reply #86 on: November 11, 2007, 08:16:41 PM »
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HenryCase wrote:
How easy would it be to port one of those examples mentioned?

It depends on what board it was intended for, what additional hardware it has, what clocks the design uses, if there is enough block RAM, how nice the I/O ports like keyboard etc. map to the MiniMig keyboard/floppy HDL.

I would imagine 10-20 mins to get something on screen. A couple of hours to get the keyboard working and "preload" BIOS ROM and snapshot data into the FPGA block RAMS and poking a start address.

Then maybe a couple of days for disk/tape emulation through the PIC, maybe less if you can wire up an old digitiser and pipe the Audio in through spare I/O.

Burrr Beeep. Burrrr, beep beep bur beep beep. (Me trying to phonetically type the sound of a Spectrum loader).

I've never researched Analog Tape but I imagine that there are several optimisations / cheats you can use when digitising that you couldnt get away with normally with normal audio.

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I mean is the h/w they normally run on fairly similar?

Yup. All the standard I/O are there. Just Analog Audio in is missing.
 

Offline AJCopland

Re: What's the point of the MiniMig?
« Reply #87 on: November 11, 2007, 10:19:51 PM »
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alexh wrote:
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HenryCase wrote:
I mean is the h/w they normally run on fairly similar?

Yup. All the standard I/O are there. Just Analog Audio in is missing.

Couldn't you erm.. cheat in the same way that the MiniMig cheaps and simply pretend it was loading from tape just as MiniMig pretends its loading form disk using ADF files on the MMC card? The internals shouldn't care where the stream of binary data was coming from as long as it was getting that data in the format that it expected.
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Offline freqmax

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Re: What's the point of the MiniMig?
« Reply #88 on: November 11, 2007, 10:58:56 PM »
For C64 there is *.tap files that are digitized casette tapes (C2N dassette).

Btw, as the FPGA sits like a gateway between cpu & memory. One should be able to implement MMU in a noncompatible way. And memory protection. Viola modified NetBSD will run :-D
 

Offline alexh

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Re: What's the point of the MiniMig?
« Reply #89 on: November 12, 2007, 12:11:35 AM »
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alexh wrote:
Then maybe a couple of days for disk/tape emulation through the PIC

Sh!t did I say that ;-)

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AJCopland wrote:
The internals shouldn't care where the stream of binary data was coming from as long as it was getting that data in the format that it expected.

At the data rate it was expecting etc. which would be the research bit that takes a couple of days. But you'd implement SNA (memory snapshots) and emulate floppy disks first.