Re: Connector P2 on 2040/4040 mainboard?

From: André Fachat <afachat_at_gmx.de>
Date: Tue, 18 Jun 2019 19:21:49 +0200
Message-ID: <16b6b9bebc8.27ff.b4d1f2b66006003a6acd9b1a7b71c3b1_at_gmx.de>
I did some worl on these drives recently.

As I'm onbthe road just a quick note.

I THINK you can just use the 8250 board as reference. It is a universal
digital board and is supposed to be jumperable to 4040 mode.

As for the analog board you could cross compare the 2031 and 4040 and 8250
analog boards, or even the apple ii disk ii board as they use the shugart
sa390 as well.

André

Am 18. Juni 2019 19:11:35 schrieb Ethan Dicks <ethan.dicks_at_gmail.com>:

> Hi, All,
>
> Some recent postings on one of the CBM groups on Facebook has turned
> my attention back to a bit of hardware I bought more than 30 years
> ago, a bare 2040/4040 mainboard.  I've been looking over the
> schematics on zimmers.net in pub/cbm/schematics/drives/old/4040 and
> there's a scan glitch on one of the pin assignments for P2, the 20-pin
> connector that goes to the analog board.
>
> Here's the pinout as I've collected from the three digital board
> schematic sheets:
>
> P2
> 1 ?
> 2 HD SEL 1
> 3 -MTR0
> 4 WP0
> 5 ACT LED 0
> 6 WP1
> 7 -MTR1
> 8 ACT LED 1
> 9 S1B
> 10 ?
> 11 ?
> 12 ?
> 13 ?
> 14 DATA OUT
> 15 DATA IN
> 16 ?
> 17 S0A
> 18 S0B
> 19 S1A
> 20 ?
>
> and a loose tag at the lower left corner of 320806-3.gif
> ? READ INHIBIT
>
> The scan glitch is I can't clearly read what pin is READ INHIBIT.  It
> could be pin 16 if the 1 is totally missing and the 6 has a void
> through it.
>
> The reason for going over this in detail is to figure out if it's
> feasible to cobble up a way to have the digital (main) board talk
> directly to an SA390/SA400 without the CBM analog board.  This is
> something I tried to do long, long ago but it was beyond my skills
> when I was a teenager.  I bought the bare digital board cheap and
> picked up a real SA400 and really should have just bought a CBM analog
> board (tossing off the Shugart analog board) but I think the local
> Commodore Dealer wanted way too much for it as a loose item, so I
> never got that drive connected up.
>
> I can always keep this digital board around as a spare for maintaining
> the 2040/4040 drives I already have but I'd kinda like to push this
> old project to completion.  I think it's possible to hack the Shugart
> analog board on the SA400 to take the signals from P2 (stepper lines
> and motor controls and LED/switch lines) because I think it's a _real_
> challenge to try to hack up a circuit to turn P2 into something
> resembling a Shugart 34-pin floppy interface.  Not impossible, but
> probably more work than hacking the drive itself.  I'm not concerned
> with trying to hack _two_ drives this way.  One is enough and was my
> original goal back in the day anyway.
>
> Yes, I have a 2031 now and an upgraded 2040 (2040 badge with 4040 DOS
> v2 firmware) so this isn't about having _a_ drive on a PET, it's about
> getting an old project across the finish line for the sense of
> accomplishment.
>
> Anyone here do any low-level work on these drives?  Any comments or
> suggestions?
>
> Thanks,
>
> -ethan
Received on 2020-05-29 21:58:11

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