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Thread: Tiny 'XT-class' machine

  1. #1
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    Default Tiny 'XT-class' machine

    Hi All,


    My name is Valentin and this is my first post to this forum, although I've been 'lurking' for quite some time now!

    I have been a long-time addict of PC hardware, ever since my folks shelled out for a PC-XT Turbo clone (8088 4.77/10MHz 640K RAM 2x360K FDD's mono screen printer etc.) back in 1987 that was upgraded over the years with the addition of a 20MB HDD, EGA, High-density drives, bus mouse, adlib card etc..

    I did eventually move on to newer hardware platforms after around 1992 i.e. 386DX-40 / Cyrix-166 / Athlon 700 / Athlon XP 1800 etc. etc. But I never really forgot about that first machine I had all those years ago!

    Around mid-2005, my XT clone powered-up for the last time.

    Then in 2008 when I was asked to build design a custom industrial controller card, I thought: 'could this tiny little board, with the right custom firmware also be made to run just like that old XT I had before?' My boss thought I was crazy! But since I had plenty of spare (after hours) time, I was up for the challenge..

    Here are the results (around 5 months part-time) of probably the most tedious work I'd ever done - enjoy!


    An early image of the hardware running MS QBASIC:
    http://members.optuszoo.com.au/pioneer10/DXDEMO1a.JPG

    A demonstration video showing the prototype running a number of past PC gaming titles:
    http://www.youtube.com/watch?v=E-Kl4uciERM

    Another video of the same prototype running a GUI and related applications (OpenGEM Version 5):
    http://www.youtube.com/watch?v=kS2YdGjhzFg

    Comments (or flames) invited!

    Regards,

    Valentin Angelovski
    Last edited by basman74; February 15th, 2010 at 08:44 PM. Reason: Tidy up

  2. #2
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    Whose chip did you use? VIA, ZF or someone else?

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    Quote Originally Posted by Chuck(G) View Post
    Whose chip did you use? VIA, ZF or someone else?
    Hi Chuck,

    Whilst I am unable to release any details of the main processor (yet), I can reveal some more background of the hardware: Early last year, I commenced design of an industrial controller for a remote site application. Since it was envisaged the system was to be powered by batteries for extended periods, it had to be consume very little power. The external keyboard/mouse circuits were part of the requirement, but the board could run without these connected..

    The early prototype in the photo has a nominal power consumption of around 0.7W @ 5V with all accessories connected as shown. These early prototypes have linear regulators on-board which waste alot of energy! Substituting these with switched-mode brings the power usage down to around 0.25-0.3W.

    The low power requirement pretty much ruled out any x86 hardware solution that I am aware of.


    Regards,

    Valentin
    Last edited by basman74; February 15th, 2010 at 10:52 PM. Reason: revised the power consumption

  4. #4
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    Hi Valentin,

    Is your design limited to 16-bit real-mode execution, or can it perform in 32-bit protected mode also? What is the resolution of your video interface?

    I've been following ZFMicro's announcements for a couple of years; their latest ZF486 claims a power consumption of under 1W with full 486 support. At one time, they offered a version with VGA LCD support, but that seems to have disappeared.

    If I have things right, it seems that your parent firm seems to specialize in automotive applications. Where do you see your product fitting into your firm's offerings. Do you think that ARM-based designs offer serious competition in that area?

    Thanks in advance for satisfying my curiosity!

  5. #5
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    Quote Originally Posted by Chuck(G) View Post
    Hi Valentin,
    Is your design limited to 16-bit real-mode execution, or can it perform in 32-bit protected mode also? What is the resolution of your video interface?
    As it stands, the system emulates 8088/86 real-mode only, with several 80188 instruction opcodes (i.e. PUSHA POPA) added, other 80188 instructions could be also added to enable Windows 3.1 to boot on this board.

    The maximum (native, therefore not accessible to the emulator) resolution of the prototype board (with it's slow display RAM) shown here is 512x400 256-colors maximum. The following link provides an example of this mode.



    Going to higher-speed memory would yield an emulated CPU speed of around 28 MHz (video out enabled), or 60-70MHz (video out disabled), fairly decent VGA 'chunky pixel' graphics along with some sound blaster capability

    Quote Originally Posted by Chuck(G) View Post
    I've been following ZFMicro's announcements for a couple of years; their latest ZF486 claims a power consumption of under 1W with full 486 support. At one time, they offered a version with VGA LCD support, but that seems to have disappeared.
    Yeah, was aware of the ZF offerings, but would still be considered overpowered (and overkill) for our original application..

    Quote Originally Posted by Chuck(G) View Post
    If I have things right, it seems that your parent firm seems to specialize in automotive applications. Where do you see your product fitting into your firm's offerings.
    Actually, there was an Industrial Automation section to the site that has been taken down for updating. My focus is Industrial Automation, not automotive related.

    Quote Originally Posted by Chuck(G) View Post
    Do you think that ARM-based designs offer serious competition in that area?
    ..or in almost any other area (excluding PC desktops, for now), yes!

    Quote Originally Posted by Chuck(G) View Post
    Thanks in advance for satisfying my curiosity!
    No problem!

    Regards,
    Valentin
    Last edited by basman74; February 16th, 2010 at 03:07 PM. Reason: Fix hyperlink

  6. #6
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    Thanks for the info, Valentin!

    Did you use something like Zet as your starting point? It appears to be very similar.

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    Quote Originally Posted by Chuck(G) View Post
    Thanks for the info, Valentin!

    Did you use something like Zet as your starting point? It appears to be very similar.
    Actually, I undertook this project long before I even knew about the existence of Zet, which is basically an FPGA implementation of an XT system (Hmm, I didn't know Dune 2 could even run on an XT? nice one! )

    Perhaps I should clarify what the DX-Demo board is not: This isn't an implementation of Zet, Bochs, PCEmu or DOSBox etc it is a very tiny emulation program written completely written from the ground up (and mostly in assembly), by me.

    DOSBox was really the only thing that inspired me to do this. However, the only way I was going to make it all fit into the tiny memory spaces of the on-board MCU, was to take all the Intel (8088,8237,8259,8253,8255) and Motorola (6845) datasheets and start reading...

    Regards,
    Valentin

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    Thank you for the clarification, Valentin. I was somehow under the impression that you'd churned out a bunch of VHDL and loaded it into a low-power FPGA. I did not realize that this was an emulator program running on a commodity microcontroller. A nice project!

  9. #9

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    Maybe you should make and sell these systems once you can release details and stuff, unless your work agreement says something like "all products created while working with company X become the propert of company X".

  10. #10
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    It would be interesting to take the idea and extend it to host an ISA bus interface, but I suspect that things become quite a bit more complicated electrically speaking, not to mention to code involved.

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