Dumb SCSI question...

[Charlie]

The nice thing about asking stupid questions on the EAB is that I keep getting intelligent rather than 'smart' answers.

I'm fortunate enough to have a Blizzard SCSI but nowhere to put the external port now the rear trapdoor has my Indivision poking out - isn't life hard?

It's given me the impetus to acutally use my SCSI for something & as Toni mentioned the subject of ACards...
...SCSI -> ACard -> IDE/CF Adapter. Lots of speed, low CPU overhead.

So on to today's dumb question:
Space is getting tight in my A1200 so rather than trying to fit an external 25pin ->50 pin adapter, then having a load of 50pin cable to deal with before I've even got to the adapters. (all squashed inside my A1200)
I was wondering if anyone knew of a straight Blizzard header to internal 50pin cable..? (long enough to feed under the floppy drive from which I can then bring the IDE - possibly)

If no such thing exists I'd make up my own cable but would need pointing in the direction of pinouts, etc.

My thanks.

[alewis]

No, its not a dumb question.

Without a schematic of the blizzard detailing the pin outs, do no accept this as authorative..

In general. The 25pin interface was a non-standard SCSI interface (ie 'hack') that appeared on some Macs. Amiga manufacturers followed it, as it shaved a few pennies off the cost.

What did they do away with? Just about all the ground wires. Very loosely speaking, with the exception of a couple of lines, all odd lines in a 50pin SCSI cable are ground.

I'd imagine the Blizzard followed the same convention, simply to ensure that using a "standard" 25-50 cable didn't fry something. But, if you have a manual page detailing the pins and could fwd/pm/post details, it would help. In the meantime, I'll have a dig on BBOAH etc, and dig out the schems/details of a 25-50pin adaptor, from which you can roll your own.

Hvae a gander at the SCSI Faq here http://www.scsifaq.org/ its a bit long in the tooth but accurate.

___________________
| SCSI DB-25S |
| SIGNAL pin(s) |
+------------------+ DB-25S (female)
| -DB(0) | 8 | _____________________________
| -DB(1) | 21 | 13\ o o o o o o o o o o o o o /1
| -DB(2) | 22 | 25\ o o o o o o o o o o o o /14
| -DB(3) | 10 | ------------------------
| -DB(4) | 23 | View from rear of computer.
| -DB(5) | 11 |
| -DB(6) | 12 |
| -DB(7) | 13 |
| -DB(P) | 20 |
| GND | 7,9,14 |
| GND |16,18,24 |
| -ATN | 17 |
| BSY | 6 |
| -ACK | 5 |
| -RST | 4 |
| -MSG | 2 |
| -SEL | 19 |
| -C/D | 15 |
| -REQ | 1 |
| -I/O | 3 |
+--

[Charlie]

Thank's very much for this.

I very much appreciate the schematic you've posted - your comments will likely save me a great deal of head-scratching when I get round to doing this.
I wholly agree with your logic & appreciate further checking would only be sensible before taking the plunge.

Thanks again.

[Toni Wilen]

I was wondering if anyone knew of a straight Blizzard header to internal 50pin cable..?

I am also planning to do this "soon".

[Charlie]

Originally Posted by Toni Wilen

I am also planning to do this "soon".

Good! I look forward to being able to plagurise your efforts.

[Photon]

Originally Posted by alewis

Hvae a gander at the SCSI Faq here http://www.scsifaq.org/ its a bit long in the tooth but accurate.

Yes, someone thinks he is a deity for getting a book published and flaunting it with (I almost said, THE) one of the worst web pages that have marred my eyes. I bet he used the html export in his congregation's license of Word.

I guess he thought he deserved some compensation for working with buses and cables all day long for decades. Another case of ludicrous on the verge of scary.

[alewis]

???

And your point is? You have a problem with the people who maintain the FAQ? Have you looked at the dates on the page... its been in that format since year dot... before then even. Of course, if form is more important than function to you...

Is your post in any way relevant or helpful to the OP comment? No.

[andy]

Originally Posted by Charlie

The nice thing about asking stupid questions on the EAB is that I keep getting intelligent rather than 'smart' answers.

...

It's given me the impetus to acutally use my SCSI for something & as Toni mentioned the subject of ACards...
...SCSI -> ACard -> IDE/CF Adapter. Lots of speed, low CPU overhead.

There's no such thing as a daft question if you don't know the answer! Besides, when it comes to cables and pinouts, double-, triple-... heck, maybe even quadruple-checking has to be a good thing! It's refreshing that EAB generally has such an environment that people are willing to help, isn't it? Look elsewhere and... Well, it ain't pretty!

Though I'm always interested in any topics and developments, Toni certainly grabbed my attention with that mention of the Acards. I have my old and noisy A590 (has anyone seen my modulator!? ) and until a few weeks ago, had the eventual purchase of a 600 or 1200 in mind (given that easier IDE-CF solution). For the foreseeable future, any of these are in all likelihood way beyond my budget - but I'd sure like to hear all that I can about the possibilities and try to learn what's out there and what I should consider.

I'll try to remember that I now have another thread to keep an eye on! Roll on the direct neural link!

Speaking of which, I wonder if Zetr0 has drawn-up some plans yet...?

[alewis]

@Charlie

Am I rightin saying that what you want to acheive, is to attach the [current?] internal IDE drive to the Blizzard SCSI, using a cable that runs from the B-SCSI to the drive internally. Is that correct?

[Toni Wilen]

Originally Posted by Toni Wilen

I am also planning to do this "soon".

Status report image attached

(it was originally old pc floppy drive cable)

[alewis]

Keep an eye on those ground pins :-)

[Toni Wilen]

Originally Posted by alewis

Keep an eye on those ground pins :-)

I don't bother with that. ACard has all grounds connected together anyway, one ground is more than enough!

[Charlie]

Originally Posted by alewis

@Charlie

Am I rightin saying that what you want to acheive, is to attach the [current?] internal IDE drive to the Blizzard SCSI, using a cable that runs from the B-SCSI to the drive internally. Is that correct?

Exactly!

Blizzard SCSI -> Internal 50pin connector -> ACard SCSI-IDE -> IDE-CF Adapter -> CF Card...
...all internal.

It's the first stage that's the tricky bit...
...my thanks for all your help, looks like Toni is well ahead of me on this one so I'll only need to apply the minimum of brain cells.

Thanks Toni (in advance)

[Photon]

Originally Posted by alewis

???

And your point is? You have a problem with the people who maintain the FAQ? Have you looked at the dates on the page... its been in that format since year dot... before then even. Of course, if form is more important than function to you...

Is your post in any way relevant or helpful to the OP comment? No.

I guess the site just came across as promoting him and his book, while appointing itself to be the official FAQ yet made with a minimum of effort. Wikipedia curiously links to another SCSI faq site, which might or might not be the REAL "super ultimate official SCSI faq site not updated in 10 years".

OK, let's get back on topic. Wouldn't mind a compact Fast SCSI-II controller with a card slot, or comparable solution. Possible?

[Toni Wilen]

Previous plan scrapped, it felt too unreliable.

Revision 2 image attached, floppy wire directly soldered to ACard (not yet 100% finished or tested)

[Photon]

Hmm, maybe combining cards into an FPGA and put it on a sidecar vertical card, with edge connector adapters for the misc Amiga models´ expansion ports? I'll ask Rave if he's up to it

If someone could scan or send a TrumpCard Pro 500 boot rom, I could have a look at its code, not to mention get my own controller booting again. I forgot how much I offered in my Marketplace thread but ... let me know if one of you has one!

[Charlie]

Originally Posted by Toni Wilen

Previous plan scrapped, it felt too unreliable.

Revision 2 image attached, floppy wire directly soldered to ACard (not yet 100% finished or tested)

Now that's my kind of hardware butchery!

Just as a matter of clarification, it's >this< ACard you're using..?

Paranoia: Despite many years of fiddling with various computers I've never had any practicable contact with SCSI* & am well aware how lack of familiarity can lead to stupid (expensive) mistakes.

*Well, Acorn SCSI, but that's a whole (much easier) other ball game.

[Toni Wilen]

Originally Posted by Charlie

Now that's my kind of hardware butchery!

Thanks. And it WORKS! Will post images when (if?) I have managed to fit it inside A1200..

Just as a matter of clarification, it's >this< ACard you're using..?

Yes

[Charlie]

Thanks.

[Toni Wilen]

It fits

(blizzard scsi -> 50pin adapter pinout will be posted later if someone needs it)