Tandy 1400 HD with Lo-Tech XT-CF won't load bios rom

[arlaneenalra]

Seems that no matter what I do with this thing, I can't get it to load the bios rom at boot. I've been able to get it to boot from an XUBDisk and then subsequently boot from the XT-CF but I can't seem to get it to load the ROM from the XT-CF itself. The ROM is present at C800 when I look with Checkit or Debug, it just won't load it. I did accidentally plug it into the hdd controller slot ( though when I double checked the pinouts, I didn't see anything there that should have been damaging ...) I've tried with both the 1.04 and 1.08 BIOS chips ( I have and FD and an HD board). I've also tried updating the flash rom with Lo-Tech's flash utility and a stand alone programmer. I can see the changes in the ROM with debug, it just won't load it.

Kind of at a loss as to what to check next.

 

[modem7]

Tandy 1400 HD with Lo-Tech XT-CF won't load bios rom

I presume that this the 'Lo-tech Tandy 1400 XT-CF' card shown at [here].

( I have and FD and an HD board)

I see at [here], the text of, "For 1400HD machines, the MFM controller must be removed since both cards have their BIOS at C800h".
Your "I did accidentally plug it into the hdd controller slot" suggests that the MFM controller is not present.

I can see the changes in the ROM with debug, it just won't load it.

A visual using DEBUG provides confidence only. Does the [RAYXTIDE tool] find the XUB at C8000, and report no problems?

 

[Malc]

What revision of the XUB was in ROM when you originally got it ?, I don't own any Tandy's but doesn't that model require ' Module_Very_Late_Init ' ? Have you tried the Pre-configured BIOS based on XTIDE Universal BIOS r567, on the Lo-Tech site https://www.lo-tech.co.uk/wiki/CompactFlash_Adapter_for_Tandy_1400_Laptops , It's old now but worth a try if you haven't done so.

 

[arlaneenalra]

I presume that this the 'Lo-tech Tandy 1400 XT-CF' card shown at [here].


I see at [here], the text of, "For 1400HD machines, the MFM controller must be removed since both cards have their BIOS at C800h".
Your "I did accidentally plug it into the hdd controller slot" suggests that the MFM controller is not present.


A visual using DEBUG provides confidence only. Does the [RAYXTIDE tool] find the XUB at C8000, and report no problems?

The mfm controller is removed, I didn't know about the RAYXTIDE tool, I'll give that a shot. My board came for Texelec and is red with pre-shorted solder pads instead of a pin jumper, but I believe it's supposed to be equivalent to the one pictured.

What revision of the XUB was in ROM when you originally got it ?, I don't own any Tandy's but doesn't that model require ' Module_Very_Late_Init ' ? Have you tried the Pre-configured BIOS based on XTIDE Universal BIOS r567, on the Lo-Tech site https://www.lo-tech.co.uk/wiki/CompactFlash_Adapter_for_Tandy_1400_Laptops , It's old now but worth a try if you haven't done so.

The board came with an r625 version on the chip, I don't know what build options were set. I've tried that and the r629 pre-built version. If itndoes need a special build, that could be the issue, I'll try out the linked build there if RAYXTIDE doesn't report an issue and I should be able to rebuild the r629 later if that works.

Thanks for the insight! I'll post an update when I get try these ideas out.

 

[arlaneenalra]

The RAYXTIDE tool was very helpful, though it is unaware of the bios for this machine. What finally got it working for me is the r567 build that @Malc mentioned. I wonder if that's something that could be added to the tool? I have both the 1.08 and 1.04 bioses handy, is there a github or equivalent project for RAYXTIDE?

Also, r567 does not play nice with warm boots. It seems to work fine on a full power cycle thought.

 

[arlaneenalra]

And to confirm MODULE_VERY_LATE_INIT was definitely the gotcha for that model. I built a version of r629 with that enabled and it appears to work fine. The one caveat is that it has to be a cold boot for the XT-IDE bios to work. Any Ctrl-Alt-Del and the XT-IDE bios can't read the flash card correctly. Power cycle the machine and it's fine again. I think this was also mentioned in one of the wiki pages so it's not unexpected. Something to toy around with later.