Bad SD Slot?

[Tom Lake]

I tried to get a list of BAS files but I got this instead:

MITS ALTAIR 680 BASIC VERSION 1.1 REV 3.2
--KCACR--
COPYRIGHT 1976 BY MITS INC.

OK
open /BAS failed (make sure it exists)

I removed the SD card and put it in my PC. It reads and writes just fine.

I tested my solder joints to the SD reader on the 680 and they all test good.

[Chris Davis]

While in BASIC, raise SW0 and toggle DEPOSIT down.  Do you see a list of files?

[Chris Davis]

Oops, I mean make sure all address switches are down, then toggle DEPOSIT down.  That should give a directory of BASIC files.

[Thomas Lake (Tom)]

Attempting to load /BAS/FILE1.TXT ...
File not found or read failed: /BAS/FILE1.TXT

---

From: altair...@googlegroups.com <altair...@googlegroups.com> on behalf of Chris Davis <famousd...@gmail.com>
Sent: Monday, January 19, 2026 1:42 PM
To: Altair-Duino <altair...@googlegroups.com>
Subject: Re: Bad SD Slot?

 

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[Tom Lake]

With all switches down I get:

open /BAS failed (make sure it exists)

[Tom Lake]

With SW0 up, I get

Attempting to load /BAS/FILE1.TXT ...
File not found or read failed: /BAS/FILE1.TXT

[Chris Davis]

I'll send another SD card module and see if that works.  You do have the six-pin female header installed under the Due?

[Tom Lake]

Yes, it's there. I'll check the solder joints on that, too.

[Chris Davis]

Also check the orientation of the card reader:

[Tom Lake]

Yup. Mine looks just like the one in your photo.

[Chris Davis]

Ok I'll send a new module out today.

[Tom Lake]

What Due pins control the SD card slot? I might as well check them while I'm waiting. I tested the solder joints at the SD end and they're OK but I didn't test the Due end.

[Chris Davis]

The schematic is here: https://adwaterandstir.com/instructions-680/

MISO, MOSI, CLK, and CS are connected to the SPI connector in the center of the Due, 3.3v and GND are connected to 3.3v and GND on the Due.

[Tom Lake]

OK, I checked all the SD card pins and they're all connected to the SPI connector and the correct power and GND pins. I'll have to wait for the replacement.

[Tom Lake]

What version of SDFat should I be using? Does it matter? I'm using 1.1.0 since the 8800 AltairDuino uses that.

On Wednesday, January 21, 2026 at 8:46:13 AM UTC-5 famousd...@gmail.com wrote:

[Charley Jones]

I had the same issue and tested all the connections back to the icsp connector, 5v, and gnd.  Replaced the reader and it worked. I think Chris got some bad miro-sd readers 

Sent from my iPhone 15pm!

Charley Jones, PMP

On Jan 23, 2026, at 4:52 PM, Tom Lake <tl...@twcny.rr.com> wrote:

What version of SDFat should I be using? Does it matter? I'm using 1.1.0 since the 8800 AltairDuino uses that.

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[Tom Lake]

OK, I solved this problem. The system didn't like the supplied SD card! When I copied the files over to an 8GB card, it worked.

Two down (1. Bad Due  2. Bad SD card), one problem (No VTL-2) to go (see latest message)