SCSI to IDE, z-80 conv:Prototype, looking for a project lead

[uniserver]

There was a thread on 68KMLA that originally talked about this board,

it was the board that used age appropriate parts.

Board is not ready yet, They are $20 bucks a piece, he has 4 PCB's left.

Here is his email to me:

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Sorry for the late reply.

Yes, there are four of the SCSI to IDE PCBs left. Are you interested in building a prototype? I know the board works well enough to run a basic debug monitor but needs a project lead with enough skills and experience to complete build and test and also work on the firmware.

The PCBs are normally $20 each plus shipping but if there is a project lead volunteer or someone who can bring this to completion, I will send them a PCB for free.

Thanks and have a nice day!

Andrew Lynch - LYNCHAJ@YAHOO.COM

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I wouldn't be much help on this project,

i bet some of you might be, if you are interested?

 

[techknight]

Let me know. Since my SCSI adapter I tried to make FAILED. lol. Can you get the schematics/Code from him? That would be extremely helpful on my end.

 

[uniserver]

just email the guy, he knows of this post.

 

[Trash80toHP_Mini]

I was hoping you'd jump in and take the lead!

Let me know. Since my SCSI adapter I tried to make FAILED. lol.

No failure, you gained valuable knowledge in the attempt and that will be directly applicable to picking up the ball where it was positioned on this other project. Cross pollination of the two strains may lead to a hybrid that works, even in that case that this variant of the project should fail as well.

The National Treasure[/i] Ben Gates"] [paraphrasing Thomas Edison, about invention of light bulb] I didn't fail, I found 2,000 ways how not to make a light bulb; I only need to find one way to make it work.

HEH! :approve:

 

[Byrd]

Perhaps the designer could be invited on here to spread the word. Obviously if the adapters worked well, he'd have a captive market as I'm sure many of us would buy several @ $20 each, along with the Amiga market too.

JB

 

[uniserver]

that price might just be for the bare PCB, parts might be up to you and extra...

 

[Trash80toHP_Mini]

IIRC, that price was for the bare development boards, Production boards would be less, I'm sure Byrd knows that.

Current price of parts calculation for determining an estimated kit price would be an interesting exercise. |)

Original discovery of project by krye: I've been looking into SCSI hard drive alternatives...



p.s. BTW, krye, that topic should have been posted in Peripherals, not in the lounge.

< mod mode >

Any project or subject that's "on topic" for the 68kMLA should be posted anywhere other than the Lounge and Trading Post.

Reasons:

The Lounge, by definition, is meant for OT discussion.

The Trading Post is obviously not the place for such posts, but the other reasons below apply to it as well.

These two forums are Bot Free and invisible to outsiders, therefore:

__It makes it easier for members to internally search for such posts within the barracks for starters, more importantly:

__it makes it possible for the troops to dredge up info in older topics while doing general searches on Google, etc.

__It makes it possible for lurkers to see such posts, so they can enlist in order to join into the discussion if interested or have good info to add.

__It makes it possible, and much more likely, for others who haven't discovered the barracks yet to find us when searching from the outside . . .

. . . yadda, yadda, yadda . . . just do it! :beige:

< /mod mode >

 

[uniserver]

Hi

Thanks for the link as I am able to see the discussion. I am active on vintage-computer.com forums related projects (XT-IDE, AT2XTKBD, etc) and home brew computing projects. However, I am not a "Mac Person" and would not be a suitable fit on a Mac related forum.

There are a vintage-computer.com forum threads to give background on the SCSI to IDE/SD project. It was supposed to be general in nature to support not just Mac but Amiga, Sun, DEC, various synthesizers, sewing machines, photocopiers, test equipment, and a variety of other equipment that are dependent on scarce and rapidly diminishing SCSI-1 drives.

http://www.vintage-computer.com/vcforum/showthread.php?22906-SCSI-1-to-from-IDE-drive-converter/page3&highlight=scsi2ide

http://www.vintage-computer.com/vcforum/showthread.php?24021-Scsi-to-IDE-converter&highlight=scsi2ide

The schematics, PCB layout, debug/monitor software, photos, build instructions, parts lists, etc are found on the N8VEM wiki in the Board Information -> Other -> SCSI to IDE/SD folder. Also the complete KiCAD EDA file set is in the same directory under Other- KiCAD. All information is free (beer & speech) and publicly available.

The SCSI to IDE/SD board is PCB only. The builders would have to assemble the board themselves using commonly available parts from Jameco, Digikey, etc. It is designed to be simple to assemble and reliable. At least the one board that I know to have been built and tested seems to confirm it. However it is still in the prototype phase and would still likely have changes before a final board went to manufacturing.

Please note this is an amateur, volunteer, non-profit, hobbyist project so please be careful to set expectations appropriately at 68kmla. I am not interested in any commercial aspects nor willing to build and test, supply components, partially or fully assembled units, etc. Basically all there is available are the PCBs with design information and any other fellow builders to complete the project.

Thanks and have a nice day!

Andrew Lynch

 

[Trash80toHP_Mini]

Heh! Looks like I posted the reasons for keeping discussion out in the open just in time.

Thanks for the link as I am able to see the discussion.

Welcome aboard as a lurker, Andrew. Thank you very much for your efforts and for being so helpful in this project turnover.

 

[olePigeon]

If everything is kept through-hole and socketable as it appears to be in that picture, I'd buy 2! Soldering so easy a caveman could do it. )

After skimming the thread, $50 for a bi-directional bridge adapter? That is awesome! WAY cheaper than the Acard, and a lot more possibilities.

 

[James1095]

While I would be happy to see *any* workable solution that could be built for a reasonable price, I still think this just screams to be done with an FPGA. A single chip could implement the entire converter, and the design could be changed on the fly by updating the code. Prices are reasonable now and dropping all the time.

 

[Gorgonops]

this just screams to be done with an FPGA

As a counterpoint, pre-assembled FPGA dev boards with enough free cells to implement a SCSI host controller + simple microcontroller start at around $50, you'll have to find one that can drive 5v logic (or you'll need to graft on some external circuitry), and it also might be hard to find a cheap one that has enough free I/O pins for the job. (SCSI to SDcard in serial mode... probably not a problem, SCSI to parallel IDE? Problem.) Once you have the design down and can churn out a finished board then the limitations of the dev boards become less important, but realistically you'll probably have to find a mail-order sweatshop that'll do the soldering for you instead of just selling bare boards. I know some people can solder fine-pitch QFPs by hand but I doubt it's *anyone's* idea of a good time.

 

[Trash80toHP_Mini]

I'm all for consolidating the unit into something small enough to fit into PowerBooks/Duos some day, but let's get something/anything up and running before worrying about the "best way" do do it in the long run.

techknight an the rest of the tech/dev support troops have a ways to go before we talk about anything "better" than a homebrew kit that is actually working.

 

[olePigeon]

If you start with a Z80 based board and work out the code, can it later be moved to an FPGA? Or are these two completely different and incompatible approaches?

 

[Gorgonops]

Or are these two completely different and incompatible approaches?

There is free source code available to embed most 8 bit CPUs into a decent size FPGA. (Z-80 cores in particular seem to be a dime a dozen.) So no, there's no technical barrier to developing the board using discrete components, perfecting the firmware, and then synthesizing the whole mess into an FPGA. The difficult part would probably be finding/developing the FPGA code to emulate the SCSI controller chip, not the CPU. There is *one* SCSI chip project listed on opencores.org and it's unfinished/defunct.

 

[trag]

I know some people can solder fine-pitch QFPs by hand but I doubt it's *anyone's* idea of a good time.

 

[Gorgonops]

Heh, Weirdo.

(Of course, that's just jealousy talking. I'm at the end of the spectrum where I have to take a Valium and breathe into a paper bag for five minutes before I touch a soldering iron to anything I care about, even if it's just pasting in a through-hole DIP socket. Of course, the *really* tense moments came earlier, whilst desoldering snipped pins to make room for the socket in the first place.)

 

[James1095]

Soldering fine-pitch SMT stuff by hand is a piece of cake, I do it on a regular basis and personally would rather do that than spend the time soldering a gazillion separate pins with a soldering iron. I can understand why many fear it though, it took me a while to take the plunge but once I did I didn't look back.

Search youtube for reflow soldering, there are lots of videos. Dab on the solder paste, plop the parts in place with tweezers and fire up the hotplate (or modified toaster oven). When the paste melts into liquid solder and flows, shut it off and let it cool. Inspect closely for bridges and clean up any that formed with some wick and presto, it's done. If you get a solder template made it's even easier but so far I've only done it by hand. Temperature controlled hotplate cost me about 40 bucks to build but I've seen it done with an electric griddle. Even small scale production runs are possible since depending on the size of the hotplate, numerous boards can be reflowed at once. Different, yes, hard, no.

As I said earlier though, I would love to see *any* dependable, working, open source SCSI-to-whatever converter come onto the scene. Once the basics are done, others can build upon it.

 

[Gorgonops]

I tell you, every time I see those videos of people deftly dropping an SMT chip on glistening solder pads and instantly forming a perfect bond it reminds me of tasks like juggling or making a pizza crust by spinning and tossing it in the air. Someone who's good at it can make it look so easy, but when you try it yourself... balls flying everywhere, pizza dough on the ceiling, dogs and cats living together, mass hysteria, etc, etc. One of these days I suppose I need to man up and try it.

As to the practicalities of the project itself, if the goal were limited to plain old 5mb/sec "slow SCSI" it's probably *just possible* that you might be able to pull off a converter entirely in software using, say, one of the faster AVR or PIC variants. They can bitbang "pretty fast"... and, look, in fact, someone has actually implemented a SCSI device using them. It's a fairly high parts-count device because he's using discrete 74LS-series parts to buffer the SCSI connector, but other than that it looks pretty simple. It does split out the functions between *two* CPUs, basically one handling the SCSI port and the other acting as "the drive"... it might be worth looking at the source code, as I wouldn't rule out *possibly* being able to compress it down to one if you were using media that natively is "semi-intelligent" and supports LBA, like an SD card.

(Edit: The designer of the RAM disk I linked to has already expanded it into a device which takes a PC card. So basically the work is already done. Converting from PC card to IDE is trivial.)