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Tandy 1400 Lo-Tech XT-CF Help

ross.dykes

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Feb 25, 2020
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Location
San Francisco, CA
Hi all, I tripped across this thread while trying to find information on configuring the XT-IDE BIOS for the 1400LT. I bought the TexElec card and it does boot just fine in my system, except that the 1400 bios appears to start the drive letters for fixed disks at D which causes some confusion. I have one original floppy drive installed as A and a gotek as B at the moment. I have to select the D drive manually whenever I turn the system on which is annoying, but likely can be fixed by configuring the default boot drive in the rom image. I'm going to try that today to see what happens.
 

ross.dykes

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Joined
Feb 25, 2020
Messages
23
Location
San Francisco, CA
It's been working great for a few days now! Drive letter issue turned out to be the Gotek somehow showing up as 2 drives, so there were a total of 3 attached from a BIOS perspective. Since these systems could only have 2 attached when a hard disk is installed it shouldn't be an issue, so the XT-IDE and a single 720K disk with possibly one attached at the external connector should be fine. This system has ROM version 2.51.70 for reference.
 

zombienerd

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Mar 31, 2017
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557
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New Hampshire
I just purchased one of these (fully assembled, ready to go) from TexElec for my 1400LT.

I have the card installed now, and it's not functioning quite how I would expect.

I'm hoping some of you may have seen this issue before and can point me in the right direction:

Precursor: I have tried 32mb, 64mb, 256mb, and 512mb industrial CF cards from Delkin and Sandisk. These are cards that have always worked in my regular XT-IDE machines.

When powering on the 1400, the XT-IDE bios does not usually list the CF Device name properly. 90% of the time it garbles the text of the name, truncates the text of the name, or doesn't display a name at all. On the 10% of the time it does display the proper device name, I can usually manage to fdisk the card. Sometimes I can get it to work 2x in a row, and format the card as well. However, I have not gotten it to reliably boot twice in a row a single time, using any of the cards I own.

I have tried prepping a card in another XT-IDE machine, then inserted it, and it gives the same problem of a Garbled name, and when doing a DIR listing, the contents can/will be garbled as well. The computer works flawlessly in floppy-drive only modes. The system passes a ram test in Checkit, so I don't believe the issue is with the Tandy (but with tech this old, you can never really know) - I have also used deoxit on the expansion bus connector, and reseated the card several times without improvement. I have no idea where to start looking next.
 

pearce_jj

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May 14, 2010
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I'd suggest looking at the 5V line - voltage and stability. CompactFlash is a dual-voltage specification, 3V3 and 5V, and the Tandy I think is CMOS? So, there could be some marginal signal levels causing problems.
 

zombienerd

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Mar 31, 2017
Messages
557
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New Hampshire
I'd suggest looking at the 5V line - voltage and stability. CompactFlash is a dual-voltage specification, 3V3 and 5V, and the Tandy I think is CMOS? So, there could be some marginal signal levels causing problems.
I rebuilt the power supply when I got the machine (had some leaky caps), but I guess it doesn't hurt to check it again. I'll add it to the list for the first thing to do before plugging the replacement board in.
 

ross.dykes

Member
Joined
Feb 25, 2020
Messages
23
Location
San Francisco, CA
All my XT-IDE cards have been very picky about the CF card they use. I've had good luck with Verbatim 2GB cards on the 1400LT, and of course the ubiquitous Cisco 64MB cards. I have not had very good luck with Sandisk for some reason.

I also had to replace a bunch of caps on my 1400LT PSU, it was a little flaky until I got that done. If you don't have the original power supply it also gets cranky if you have less than 15V on the input, and if the battery is dead and the supply voltage is low the 5v line gets unstable. Good way to check is to give it the sniff test, if it smells at all like fish, then one of the caps is still leaking!
 
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