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Just Another... XT IDE, now with RTC.

RafaelBR

RafaelBR

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Joined
Feb 7, 2026
Messages
9
People of the Good Earth,

I'm nearing the final version of my variation of the amazing XT IDE project.

I decided to add an RTC... bringing more joy to circuit board design, which is a lot of fun for me.

I need to know what you think, anything I can do or improve? I just saw a small conflict that the user might have with the address selection between IDE and RTC.

The schematics used were:
XT IDE Rev 4 2018 - GlitchWorks
RTC8088 3.0 - Sergey Kiselev

Design inspiration from the Monotech team.

Several mechanical adjustments were made, such as custom pads, with more space in the areas where the user needs to solder. Where it's not needed, there's less space.

I also tried to distribute the components in the best way possible; the downside is the excessive number of vias.

Tracks were smoothed at turns whenever possible, avoiding 90-degree turns.

Minimalist silkscreen.

I don't plan on selling it commercially, as everything is extremely difficult in my country, but if I'm successful, I should make the ingredients and gerbers available on my git.

Thank you for your time...
 

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I'm personally fond of the DS1215/1315 phantom clocks instead of a full RTC (it just leeches off the decoding you added for the XT ROM anyway), but the chips are getting harder to find than they used to be. Places like Mouser *do* stock the 1315, but they want a positively absurd amount of money for one.
 
I've sort of asked myself "what a SixPack style card looks like in 202x".

I could see putting an XT-IDE, a CH375/6, a clock, and a bunch of SRAM to fill out 640k/UMBs or potentially XMS, but what else? While serial and parallel were vital in the original era, do they still make sense, or would it be better to do something like a wifi-modem?
 
Hak Foo said:
I've sort of asked myself "what a SixPack style card looks like in 202x".
Click to expand...

I’ve called the expansion board I built for my plus-bus Tandy 1000’s a “six pack”, enumerated like this:

  1. Conventional RAM + UMB
  2. EMS (1MB)
  3. XT-CF
  4. Clock
  5. Serial port 1
  6. Serial port 2 (used a 16552 dual UART)
This is with all through-hole on a card that (barely) fits inside the Tandy Plus-Bus form factor limits, with surface mount on an ISA card you could easily add a parallel port (there’s a reasonably easy to get ASIC that’s like a 16552 but also has a parallel port), a CH375, an AS8019 Ethernet chip, up to 4MB EMS… etc. Or you could just do what all the cool kids seem to want to do these days and slap a Pi Pico on it.
 
I was going to add that most people seem to want audio and networking on their XT nowadays so the pico cards that do most of this seems to be the cheapest and most straightforward way to go.
 
I think there are three of these MCU based ISA community projects out there, PicoGUS and two RAM expansion cards based on Teensy and RPi, who both also have disk, networking and some audio amongst probably another things.

Cheap and everything you need out of swiss army knife card - I guess even if you need extra serial or parallel communications the code can be added and USB can be used as physical layer.
 
As long as parallel SRAMs are available and relatively cheap I would personally rather keep RAM “real”, but yes, the whole virtual peripheral thing is becoming the path of least resistance for things like networking, sound card emulation, etc.
 
RafaelBR said:
People of the Good Earth,

I'm nearing the final version of my variation of the amazing XT IDE project.

I decided to add an RTC... bringing more joy to circuit board design, which is a lot of fun for me.

I need to know what you think, anything I can do or improve? I just saw a small conflict that the user might have with the address selection between IDE and RTC.

The schematics used were:
XT IDE Rev 4 2018 - GlitchWorks
RTC8088 3.0 - Sergey Kiselev
Click to expand...
Looks cool!

Question... how large of an EEPROM were you planning to include on it? Reason I ask, I have an option ROM project called GLaTICK that implements the RTC BIOS calls included in ATs and beyond used by DOS so that you don't need any drivers or clock utilities on an XT. It is only 2K so if you had at least 16 KB of ROM on the card both XUB (the 12k version) could be fit and you'd have the benefit of both!

640KB
 
Another thing to cram in to the EPROM would be something that allows using HD floppies.
 
Hak Foo said:
I've sort of asked myself "what a SixPack style card looks like in 202x".

I could see putting an XT-IDE, a CH375/6, a clock, and a bunch of SRAM to fill out 640k/UMBs or potentially XMS, but what else? While serial and parallel were vital in the original era, do they still make sense, or would it be better to do something like a wifi-modem?
Click to expand...
Looks like you describe the PicoMEM 2 ... and forgot lot of other things it can do :)
 
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