NuXT - MicroATX Turbo XT Motherboard - 9.55MHz, UMBs, XT-CF, SVGA, HD Floppy, Serial

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NuXT - MicroATX Turbo XT Motherboard - 9.55MHz, UMBs, XT-CF, SVGA, HD Floppy, Serial

Postby nztdm » 2019-6-06 @ 13:15

Hello all

I've designed a MicroATX XT motherboard based on Sergey Kiselev's Micro 8088 SBC and ISA cards as seen here: http://www.malinov.com/Home/sergeys-projects

Can be used as a full featured XT without any cards.

Image Image

Image

    Features:
  • 8088 and NEC V20 support
  • 8087 co-processor support
  • 4.77MHz, switchable to 9.55MHz with Ctrl-Alt-+
  • 2x64K ROM, switchable with DIP switch, writable
  • 832K RAM
    - 640K conventional
    - up to 192K UMBs (160K max when using VGA)
    - Configured DOS 6.22 uses only 10K conventional!
  • Onboard TVGA9000i SVGA
  • HD Floppy controller, with FM support
  • Bootable CF Card Interface
  • Option ROM Socket, supporting 8K and 32K ROMs, writable
  • 16550 Serial Port
  • PS/2 Keyboard Port
  • ATX Power Input. Generates own -5V
  • 4 x 8-bit ISA Slots
  • ASUS-style front-panel connector for modern cases

The project is at Revision 1.2, with all known bugs ironed out.

Source files are here on Github if you'd like to make one.

All parts are still in production today, except:
FE2010A XT chipset (hard to find)
TVGA9000i VGA chipset (hard to find, optional)
PC8477BV-1 floppy controller (plentiful on eBay, optional)

I have some parts, and will be offering complete boards and DIY kits here.

Cheers
JD
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Re: NuXT - MicroATX Turbo XT Motherboard - 9.55MHz, UMBs, XT-CF, SVGA, HD Floppy, Serial

Postby twilliamc » 2019-6-06 @ 13:34

I love this. Any hope for a 3D printed I/O shield?
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Re: NuXT - MicroATX Turbo XT Motherboard - 9.55MHz, UMBs, XT-CF, SVGA, HD Floppy, Serial

Postby nztdm » 2019-6-06 @ 13:36

twilliamc wrote:I love this. Any hope for a 3D printed I/O shield?


Glad you like it!
I don't have 3D modelling experience, but could give dimensions to someone that does, or they can look at the gerber files.

You can get blank metal I/O shields on eBay. Would need laser cutting machinery for those.. or d-sub punches..
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Re: NuXT - MicroATX Turbo XT Motherboard - 9.55MHz, UMBs, XT-CF, SVGA, HD Floppy, Serial

Postby BinaryDemon » 2019-6-06 @ 14:12

Very cool, just curious why did you lay the power connector horizontal?
Check out DOSBox Distro:

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a lightweight Linux distro (tinycore) which boots off a usb flash drive and goes straight to DOSBox.

Make your dos retrogaming experience portable!
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Re: NuXT - MicroATX Turbo XT Motherboard - 9.55MHz, UMBs, XT-CF, SVGA, HD Floppy, Serial

Postby nztdm » 2019-6-06 @ 14:17

BinaryDemon wrote:Very cool, just curious why did you lay the power connector horizontal?


Thanks :)

And because I like the look of a side-entering ATX connector more.
This board is not as wide as MicroATX boards can be, so there is plenty of space in a MicroATX case.
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Re: NuXT - MicroATX Turbo XT Motherboard - 9.55MHz, UMBs, XT-CF, SVGA, HD Floppy, Serial

Postby SirNickity » 2019-6-06 @ 18:15

That is the most beautiful thing I have ever seen this morning. LOL

Somebody with significantly better FPGA skills than me needs to get in there and clone those ICs. What's the story on the BIOS? Was it hand-crafted or ported from some existing hardware?
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Re: NuXT - MicroATX Turbo XT Motherboard - 9.55MHz, UMBs, XT-CF, SVGA, HD Floppy, Serial

Postby Mixeur » 2019-6-06 @ 20:34

Great ! But expensive. As you are using my NEC V20's photo without permission, I think I desserve a discount, don't you ? :cool:
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Re: NuXT - MicroATX Turbo XT Motherboard - 9.55MHz, UMBs, XT-CF, SVGA, HD Floppy, Serial

Postby mothergoose729 » 2019-6-06 @ 21:48

This is awesome. I would very much like to be a customer someday. Do you have a fixed inventory? How long might these be available?
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Re: NuXT - MicroATX Turbo XT Motherboard - 9.55MHz, UMBs, XT-CF, SVGA, HD Floppy, Serial

Postby nztdm » 2019-6-07 @ 00:53

SirNickity wrote:That is the most beautiful thing I have ever seen this morning. LOL

Somebody with significantly better FPGA skills than me needs to get in there and clone those ICs. What's the story on the BIOS? Was it hand-crafted or ported from some existing hardware?


Glad you like!

Go to the first link in the original post. This is based off Sergey Kiselev's Micro 8088 SBC, and uses the BIOS he wrote.

Mixeur wrote:Great ! But expensive. As you are using my NEC V20's photo without permission, I think I desserve a discount, don't you ? :cool:


!!! I am sorry! That was the best photo on Google images after a 5 second search. I will take my own photo.

Tiido wrote:This is very cool ~


Glad you like!

mothergoose729 wrote:This is awesome. I would very much like to be a customer someday. Do you have a fixed inventory? How long might these be available?


I have a few of the rare chips left, and the rest of the parts I can get forever. I can probably supply them for at least a year.
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Re: NuXT - MicroATX Turbo XT Motherboard - 9.55MHz, UMBs, XT-CF, SVGA, HD Floppy, Serial

Postby mwdmeyer » 2019-6-07 @ 05:54

Highly recommended product and seller. I have a white version which is way cooler 8)
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Re: NuXT - MicroATX Turbo XT Motherboard - 9.55MHz, UMBs, XT-CF, SVGA, HD Floppy, Serial

Postby Caluser2000 » 2019-6-07 @ 06:08

Agreed. Welcome to the forum Jacob. I got an XT-IDE card off him. Excellent workmanship.

Mark from down the road :)
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Re: NuXT - MicroATX Turbo XT Motherboard - 9.55MHz, UMBs, XT-CF, SVGA, HD Floppy, Serial

Postby Merovign » 2019-6-07 @ 08:28

To mashup Futurama's Fry and Groucho Marx: "SHUT UP AND TAKE MY MONEY... if I had money."

This might be *perfect* for a project I've been thinking about for a while - which will take a while to start so hopefully I'll have the money by then.

Building this would be *highly* entertaining as long as I didn't break anything.

mwdmeyer wrote:Highly recommended product and seller. I have a white version which is way cooler 8)


OOOOOOOHHH! (selling things intensifies)

Imagine one of these as a 3D printed case with an LCD, Cherry MX keyboard, and this motherboard (and I figure one of those small-form-factor PSUs):

1977-IMSAI-VDP-80.jpg


1980-IntelligentSystemsCorporation-Intecolor8963.jpg


1983-NEC-APC-8086.jpg
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Re: NuXT - MicroATX Turbo XT Motherboard - 9.55MHz, UMBs, XT-CF, SVGA, HD Floppy, Serial

Postby SirNickity » 2019-6-07 @ 19:12

I don't need one, but it's so pretty that I want one anyway. :roll:
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Re: NuXT - MicroATX Turbo XT Motherboard - 9.55MHz, UMBs, XT-CF, SVGA, HD Floppy, Serial

Postby root42 » 2019-6-07 @ 19:49

Yeah, if we now had someone making nice desktop cases, with 3.5“ and 5.25“ drive bays. That would be nice. We could make our own Vogons PCs.
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Re: NuXT - MicroATX Turbo XT Motherboard - 9.55MHz, UMBs, XT-CF, SVGA, HD Floppy, Serial

Postby MrSmiley381 » 2019-6-09 @ 21:54

Throw another vote into the ballot box in favor of 3D-printed I/O shields and options for slim or full-featured cases. If this had a printer port by default adding ethernet would be pretty easy too, right?

I've purchased some stuff from NZTDM's eBay store and it's all been top notch stuff. I'd love to see you implement a PS/2 to serial mouse converter next. I've heard of some efforts doing that before but I don't know how successful it was.

Also, is the turbo circuit based on the one Sergey mentions here? Another aftermarket drop-in mod I'd like to see is a PC-Sprint clone. A base 8088 can hardly handle Number Munchers, but I've had it run well at 8088 10 MHz speed. Not sure how stable a typical XT would be at that speed even with the extra circuitry to slow down for floppy access, but I'm curious in the name of science and highly adaptable ancient computers.
I spend my days fighting with clunky software so I can afford to spend my evenings fighting with clunky hardware.
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Re: NuXT - MicroATX Turbo XT Motherboard - 9.55MHz, UMBs, XT-CF, SVGA, HD Floppy, Serial

Postby Jo22 » 2019-6-09 @ 23:15

These pictures do remind me of the VT100 terminals from the 1970s. Before computer equipment got degraded to consumer products.
Some versions or clones had CPU boards installed, making them able to run CP/M (VT180 model) and other microcomputer OSes of the time.

PS: I wished orange plasma screens were still available. Or hi-res monochrome LCDs with electroluminescent backlight.
Or OLED displays, at least. Modern LCDs are so sterile and boring by comparison.

Edit: Sorry for being off-topic. The mainboard looks well made, indeed, ^_^
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Re: NuXT - MicroATX Turbo XT Motherboard - 9.55MHz, UMBs, XT-CF, SVGA, HD Floppy, Serial

Postby SirNickity » 2019-6-10 @ 22:48

MrSmiley381 wrote:I'd love to see you implement a PS/2 to serial mouse converter next. I've heard of some efforts doing that before but I don't know how successful it was.


Working on that one myself. I've been writing PS/2 host/device code since Friday. Almost done with the hardware layer, then just need to implement the mouse and KB protocols on top. I'm actually doing this to build a PS/2 to XT converter, since I, uh, apparently needed a Tandy 1000 for .. reasons. But, I also have a 386 and 486 w/o PS/2 that need conversion to serial so I can use them on my KVM.
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Re: NuXT - MicroATX Turbo XT Motherboard - 9.55MHz, UMBs, XT-CF, SVGA, HD Floppy, Serial

Postby nztdm » 2019-6-10 @ 22:58

SirNickity wrote:
MrSmiley381 wrote:I'd love to see you implement a PS/2 to serial mouse converter next. I've heard of some efforts doing that before but I don't know how successful it was.


Working on that one myself. I've been writing PS/2 host/device code since Friday. Almost done with the hardware layer, then just need to implement the mouse and KB protocols on top. I'm actually doing this to build a PS/2 to XT converter, since I, uh, apparently needed a Tandy 1000 for .. reasons. But, I also have a 386 and 486 w/o PS/2 that need conversion to serial so I can use them on my KVM.


There is this PS/2 to XT Keyboard Converter that I build.
https://monotech.fwscart.com/PS2_to_XT_ ... 14002.aspx
Out of stock until I get around to drilling the enclosures for the next batch.

I do plan on a PS/2 to Serial Mouse converter box at some stage, that can optionally be mounted inside a PC.
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Re: NuXT - MicroATX Turbo XT Motherboard - 9.55MHz, UMBs, XT-CF, SVGA, HD Floppy, Serial

Postby SirNickity » 2019-6-11 @ 18:19

Looks really nice, but you know how it is. I can, so I will. Well, that and I acquired a Tandy 1000 RL -- so I need XT on a PS/2 port. I could use another adapter for that, but I also need to deal with that TTL RGB port. Since I'll have +5V from the PS/2 port anyway, I decided to make a project out of it and build an inline adapter box that would accept a real PS/2 keyboard and output analog... not quite VGA, but RGB @ 15kHz that the OSSC should be able to cope with. For my trouble, I'll end up with a code library for PS/2 and XT protocols, and a lookup table for AT and XT scan codes -- which ought to be handy to have around.
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