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Anyone Selling XT-IDE Cards?

tempest

tempest

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Sep 16, 2014
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SE Michigan
Is anyone making and selling XT-IDE cards? Making one myself is beyond my skills, and the tiny 20MB hard drive in my 5150 isn't nearly big enough. I see a lot of people discussing the card and I've found parts lists, but I don't see anyone actually selling them (perhaps there's a reason for this?).
 
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I've got a few left on hand, I'll PM you about it.

Posted this publicly so that future searchers for XT-IDE will find it! I have bare rev 2 boards on hand, and can assemble + test as well.
 
I'd love one, either bag of parts or fully assembled.

glitch said:
I've got a few left on hand, I'll PM you about it.

Posted this publicly so that future searchers for XT-IDE will find it! I have bare rev 2 boards on hand, and can assemble + test as well.
Click to expand...
 
OK, so I don't have enough for everyone who wants one, which means it's time to do another XT-IDE run! Now, as someone who's personally assembled probably 20-25 XT-IDE boards, including some from the original run, I have a few things I'd like to change and come up with a Rev 3 board. Some of them are minor technical details (resizing pin header holes to better accommodate the detent headers I use, for example), but some are function changes:

- Return to DIP switches, much nicer than jumpers in my opinion
- Removal of UART circuit (not one board I've assembled was requested to have it)
- Removal of 4-pin Molex power connector, everyone is using CF or industrial Flash modules
- Permanent "Chuck mod"
- Switch to 74xx373 latches (more common in hobbyist parts bins, IMO)

Does anyone see a problem with any of these mods? Obviously the Rev 2 design could still be run, and I can run it as well if people really want the Rev 2 unmodified.

Additionally, I'll be optimizing the board for size, which should get the cost down a little per-board. I should still be able to do hard gold plating on the edge connectors. I'll try and put as much documentation on the silkscreen as possible. I'd like to stick with the "All TTL" design to make it easier for future builders to get an XT-IDE up and going without having to worry about programming GALs and such. I see no reason to switch to surface mount parts since the ISA card edge and 40-pin connector constrain the size of the board anyway.

Moderators, does someone want to rename this thread "XT-IDE Version 3"?
 
What's the Chuck Mod?

EDIT: Looks like I can't change the thread title after all.
 
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tempest said:
What's the Chuck Mod?
Click to expand...

ChuckG figured out that two of the ports could be put on consecutive I/O addresses and accessed with a single 16-bit instruction rather than two 8-bit instructions. This makes it much faster.
 
Huh, didn't know about that list. I'm still going to go ahead with XT-IDE rev 3 -- in looking through the schematic, I found what I think are some pretty good improvements to make. It'll be much easier to configure!

I noticed the upper six I/O address bits aren't decoded. From what I understand, this is "sort of" OK on old ISA systems, but has the potential to cause address conflicts due to the card repeating through address space. Seems like the card really should decode them for maximum compatibility and minimum headache. Probably end up doing it with diode-OR since I'm trying to stay away from a GAL. I'll start a separate thread about it.
 
Half-Saint said:
Yes, he is. However, the board is using a standard IDE connector so any ATA hard drive should work.
Click to expand...

It looks like he's selling the Lo-Tech XT-CF V3, So it's suitable for CF but not 'Any ATA hard drive', Only ATA-2 compliant hard drives.
 
Yeah, no latches for the upper byte. I suppose 8-bit IDE drives would also work, but don't expect usual 16-bit IDE drives to work unless, as Malc said, it specifically supports it. I didn't know it was in the ATA-2 spec.
 
Does anyone know why D7 (pin 3) on the IDE bus is pulled down via 10K resistor to ground? None of the other data bus lines are pulled down, I can't find a requirement for it in the IDE spec...doesn't make sense to me. It's also pulled down on the XT-CF Lite board, according to its schematic.
 
iam also intrested in these XT-IDE controllers. Iam not intrested in the XT-CF versions.
 
I am also interested in 1 or 2 of them. Isn't it possible to utilize a CF card with an IDE adapter if you went with just the XT-IDE adapter?
 
smyke said:
Isn't it possible to utilize a CF card with an IDE adapter if you went with just the XT-IDE adapter?
Click to expand...

Yes, I'd guess this or industrial Flash modules (DOMs) are the most popular uses for XT-IDEs.

Quick update, I've almost finished with the new layout. Probably order a prototype run this week.
 
I think the prototype layout is finished:

aPvmPxP.png


Changes:

- No UART
- Removed some extraneous pullup/pulldown resistors
- Sense is now ON == 1 for the config switches
- ROM and I/O port options all switch configured
- Decoding an extra bit on the I/O port, gives more possible port options
- Single LED/connector option
- Switch/Jumper descriptions added to silkscreen
- Jumper header hole size adjusted for detent pin headers
- Simplified settings for 28C64B/28C256 EEPROM selection
- Swapped status/control latch for buffer (latch was always enabled, it was being used as a buffer)
- Removed silkscreen around ISA connector and screw holes
- All component values placed inside part legends, values placed outside
- Capacitors optimized for axial bead type capacitors

I ended up leaving the jumpers for the Chuck Mod option rather than permanent Chuck Mod, since the V1 BIOS doesn't seem to support Chuck Mod. I also left the 74LS537 latches as apparently I ordered a quantity of them a while back, so I've got plenty for kits. The board is somewhat smaller than the rev 2 boards. I also left the I/O decoder alone w.r.t the upper 6 I/O address bits.
 
As per RetroHacker_'s request on #vc IRC, J1 has been moved so it's not possible to accidentally put the IDE connector in its position during assembly!
 
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