FPGA Altair Advice

I was working on a Macintosh clone project (a clone of the original

128k), but I'm not willing to invest any more time in something that Apple would probably kill with a C&D order.

I'm now working on a hardware replica of the Altair. I'm scanning the PCB layout and creating historically accurate replicas. I've come to the conclusion that the average person is not going to be able to afford a kit "just for the fun of it". There are literally square feet of PCBs required and a lot of the components will be expensive.

This leads me to the idea of putting the Altair into an FPGA for people who want the blinking light effect but could care less about the guts. This would be similar to the PDP-8 clone that is an inch thick and can be hung on a wall like an interactive picture. I don't have any experience designing logic for FPGAs, but like learning C/Assembler/Visual basic...I can probably use code examples to teach myself.

Basically what I'm looking for is an FPGA development board that would be suited to hold the 8080. I would also like to integrate an "optional" boot ROM, RAM, serial card, cassette card, etc. These devices wouldn't take up too many resources I'd think.

The only possible problem I can think of for an Altair FPGA is that I would want all the bus signals brought out for the front panel and for optional interface cards. Is the T80 core accurate enough to produce the two clock phases and all of the bus signals?

What development board would you suggest I buy for this purpose? I've heard about schematic entry for the logic, and I'd like to have that tool as an option.

Thanks for your time, Grant

Reply to
logjam
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Grant,

A bit off your topic, but building any computing machine for your own use is perfectly legal. Oh so it was the last time I checked.

Xerox PARC tried to buy a DEC 10, but DEC wouldn't sell them one. So, Xerox got the schematics, put everyone to work, and built one. Just one. Used it for research. Even made their own operating system for it.

Nothing DEC could do: Xerox PARC did not derive any profit from it, did not use it to do any product (and they had the losses to prove it!).

I wonder if today Apple would even care if you went into business offering (old) Mac Clones?

As long as you are not using their IP, their patents (and not impacting their present business), they really have no reason to care.

An Altair clone? Why? So that you could use those old S100 interface pcbs? Run CPM?

Austin

Reply to
Austin Lesea

Well, all of the old mac websites were sent C&D letters threating them if they didn't remove system software required to run a mac from 1984.

If you aren't a mac guy already, it would be pretty hard to get one of those old machines running because of Apple's actions.

Altair clone, because, I don't know...its the Altair! :) I want to make a computer "kit" and have it be useful at the same time.

Reply to
logjam

You could write to Steve, and tell him what you are trying to do ?

Ponders: With the new Intel MACs, and Linux FPGA tools, how close are we to being able to do a FPGA build of a MAC, on an Apple PC ? [ Apple's marketing guys could love that.... ]

Mention that more enlightened companies, like Borland

- and even (gasp) Microsoft have Museum policies, where you can either download, or freely use, some of their really old software. Some companies are proud of their heritage..... and the WEB is ideal for this type of repositry.

In some cases is it just a lawyer reflex, or they may be worried about possible support questions, but the commercial impact is going to be Nil.

-jg

Reply to
Jim Granville

No, no two-phase clock. You'd have to add something to generate it. The T80 bus is much closer to the Z80 bus than the 8080 bus.

I like the Spartan-3 Starter Kit, which you can buy from Digilent with an XC3S1000 for $149.

The I/O expansion connectors suck, though.

Personally, I find it much easier to deal with equations in an HDL. I can understand logic symbols on a schematic just fine, but if someone asks me to draw a schematic, it takes me more time to convert my mental concept into a bunch of logic symbols than to just type an equation. However, other people find the opposite to be true.

Anyhow, the Altair logic uses lots of asynchronous crap like one-shots. I suppose you could simulate the oneshots by counters with a really high clock rate, but the design would still be fundametally asynchronous. Async logic in FPGAs is not a good idea; other people here can tell you horror stories about it.

Reply to
Eric Smith

No. Xerox wouldn't let them, since they'd just purchased Scientific Data Systems (SDS), which they renamed to XDS. The corporate types thought (perhaps correctly) that it would negatively impact XDS sales if customers got wind that XDS machines weren't good enough for Xerox' own internal use.

Of course, the fact that PARC built their own PDP-10 rather than using XDS machines would send the same message to customers.

Xerox may or may not have had the DEC schematics, but they designed their own PDP-10 clone ("MAXC") from the ground up. There was no real similarity to the DEC hardware; MAXC was simply designed to execute the same instruction set.

Two, actually. And the second was a redesign, not a copy of the first.

They wrote their own operating systems for various small computers they developed, but on MAXC they used TENEX, which came from BBN. A few years later DEC used TENEX as the basis for TOPS-20, which ran on the PDP-10 processor of the DECSYSTEM-20.

That wasn't the issue. There weren't any patents on the PDP-10 instruction set. If there were, DEC might have had grounds to sue, even though PARC didn't ship it as a product.

Profit is not the same as economic benefit. Even if Xerox posted a loss every year that they were using MAXC, it's quite possible that they would have had a larger loss without it. MAXC contributed to the development of many successful Xerox products.

If company A sells some patented product P, and company B decides that buying a P would save them lots of money, but builds their own P to save even more, you can bet that company A will sue if they get wind of it.

Unless, of course, company B develops P2, which does not use the patent claims held by A. In which case they still might get sued, but will have a better defense.

I've personally been involved in a case where a company build a clone of something, carefully avoiding the patents, but was threatened with litigation and negotiated a license rather than spend a bunch of money to try to defend it.

They're not going to care unless you include a copy of the Mac ROM, which is the main component of the "secret sauce" of the Macintosh.

But of what use is a Mac clone without a ROM? It's arguably of even less use than a newborn baby.

Reply to
Eric Smith

There are various fpga/retro boards out there. In particular, there is one from a woman in germany, who wanted to replicate the C64/C128 in an fpga board. I forget the exact name. Anyways, they've got things going to the point of having a number of different cores availabe, I believe even some atari/etc ones. I'm sure they'd welcome someone doing an altair "port"...

--
 [100~Plax]sb16i0A2172656B63616820636420726568746F6E61207473754A[dZ1!=b]salax
Reply to
Tobias Weingartner

that woman is Jeri and he is not from Germany but from the US, he designed and VERY UNSUCCESFUL C1- computer, sold some distribution rights to an german guy who paid her in advance, manufactred the boards and got financial loss afterwards as Jeri did not keep her part of the deal (did not deliver anything working ip cores).

there was later a guy Tobias from Germany who did that what Jeri was commited todo, eg write functional IP cores for C1, including several retro engines.

but Tobias also got really pissed on Jeri and the C1, so he is currenty supporting more the TREX C1 board

I do have the old C1 board, its just collecting dust somewhere. do not buy the C1 take eiter TREX C1 or Trenz retro or somethin else

antti

Reply to
Antti Lukats

Grant

If you are looking for a development board with lots of uncommitted I/O to add modules then have a look at our Raggedstone1 and Broaddown2 products. Our MINI-CAN product also has a lot I/O but is slightly harder to use. There should be details of a pile of add-on modules appearing on our website sometime this week for Raggedstone1 and Broaddown2 which may also be of use.

If you don't need the PCI on these boards we have a connection module that allows the use of the interface to create 50 I/O which is 5V tolerant. We also have a I/O connection SODIMM that fits the socket on Broaddown2 giving a large pile of extra I/O on that product.

If those are not enough Broaddown4 (Virtex-4 - various up to LX160) will on sale shortly soon to be followed by Broaddown3 (XC3S4000/5000). Both these product will offer very large I/O counts.

John Adair Enterpoint Ltd. - Home of Broaddown2. The Ultimate Spartan-3 Development Board.

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Reply to
John Adair

I'm interested in these kits Eric. What else other than the board would you recomend I get? Does this board come with things like a VGA core? I read on some dev board descriptions that they came with a few modules ready to use. Are the WebPack tools good enough?

I love the 96 uncomitted I/O on the dev-board. This will allow the Altair's switches and LEDs to be connected without a bunch of logic other than buffers. :) I've got some crazy ideas for a "serial port" inside the FPGA that emulates a terminal with the VGA and PS2 port, but I'm not sure how practical that is yet. ;)

Also on a completely different project, I need some advice. I'm building a 176wX110h pixel display using LEDs. I'm almost half way through soldering! ;) I plan on it being a memory mapped display for the Altair. I bought a bunch of LEDs surplus a while back and have to use them. Plus, the Altair is all about blinking lights...but I don't know of an Altair with 17,000+ blinking LEDs. :)

The project requires 110 shift registers to be loaded every 14ms. I'm going to use some dual port SRAM from cypress, which will basically take care of ALL the Altair's RAM needs! ;) Would a good beginning project be an FPGA which reads from the dual port SRAM and sends the correct byte to the correct shift register? Basically a compicated parallel to serial converter? An evolution of the project will be character generation ability (I organized the display as 22x10 characters of 8x11 pixels)

This looks like a good board for the project:

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Any suggestions on either crazy project would be great to have. :)

Reply to
logjam

If you're willinng to try an HDL instead of schematic entry, you should get a good book on the one you choose. I don't have any recommendations for Verilog, but for VHDL you would want "Designer's Guide to VHDL" by Ashenden.

There are some demos. I think there was one that did VGA video.

"VGA core" is somewhat ambiguous. I haven't seen any free core that actually implements VGA (i.e., the register-level programming interface of the IBM VGA display adapter). But there are many cores that can drive a VGA monitor.

Yes.

Yes. Shouldn't be too difficult.

Reply to
Eric Smith

Hello Grant, I really must get back on line at home - the whole world has come back with good answers already.

I would use a HDL entry method, much easier and flexible in the long run, despite the steeper learning curve.

The T80 core (at least the maintained version on the fpgaarcade site) is getting very close to the exact behaviour of a real Z80. However, the bus timing has been simplified slightly for synchronous FPGA work. You will need to generate a two phase clock yourself, but look at some of the other code (for example the Z80 based Bally) which uses a small counter to clock enable the cpu core and generate phase signals for the chipset. Try and convert the logic to synchronous operation otherwise you may have trouble. There is another top level wrapper for the T80 core (T80a) which should work with your peripherals - it is the one I used when I tested the core with a real Z80, although it has not been tested in a while.

I would personally go with a Spartan3 based dev board (3E if you can get one). There are many good ones around. Good luck,

Cheers, Mike

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logjam wrote:

Reply to
fpgaarcade

What's the pricepoint/eta on these? :-)

--Toby.

Reply to
Tobias Weingartner

Hey guys. I believe Grant wants to make an EXACT clone of the Mac. I agree about the "Firmware" issue. As software is has an unlimited, or at least very long life span. Of course being sewed for an exact clone is possible, I don't think Apple would care unless you somehow manage to become some major market player by doing so, which is even more unlikely then being sued in the first place.

I'm currently cloning an old SCSI controller from Apple, ROM included, if they do try and send a "nasty-gram" I will promptly remove the ROM from the card and anyone who purchases the card could just download the ROM from a number of other sites and burn their own. The fact that Apple isn't going after these "other" sites is probably a good indication that they just don't give a crap one way or another about it. Need I mention the expense and bad publicity if they were to do so, and for what? They couldn't stop me selling the hardware, just their Firmware.

I say screw em' Grant, and do it anyway. I can only hope they try and sew me. I'd love to go on CNN and be interviewed. Free advertising!

Henry S. Courbis

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Reply to
Henry

Wow! Late night. Funny... I meant sued. ;) Geeze!

Henry S. Courbis

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Reply to
Henry

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