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Forum Index : Microcontroller and PC projects : Something else
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knivd Regular Member Joined: 07/09/2014 Location: United KingdomPosts: 71 |
Here is a project I've been fiddling with for the past few months. It is inspired by the early MM but runs C :) http://ello.cc |
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Rado Regular Member Joined: 27/11/2020 Location: CroatiaPosts: 59 |
That looks nice. I think that in the documentation, where you put "premium": "While there is an execution speed premium to this, a benefit is the possibility to run sources directly from a read-only memory." you actually meant "penalty"? (also, I can't see PS/2 connector in the picture?) |
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knivd Regular Member Joined: 07/09/2014 Location: United KingdomPosts: 71 |
Yes, a typo, or whatever it is called when you use the wrong word... I will fix that. Here is the PS/2 too |
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matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 8517 |
Very neat Couple of minor issues on the schematic. You are being a bit unkind on any VGA monitor by not clamping the RGB outputs to 0.7V. Also, dual mode USB/PS2 keyboards and mice seem to set their mode based on the presence or absence of pullups on the clock and data lines. Whereas PS2 only devices will work with the schematic as drawn we have found on the CMM2 that 4K7 pullups are essential for dual mode mice to work in PS2 mode and I assume the issue will be the same for dual mode keyboards |
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zeitfest Guru Joined: 31/07/2019 Location: AustraliaPosts: 369 |
includes a tiny C interpreter now thats tricky. Edited 2021-02-26 20:30 by zeitfest |
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knivd Regular Member Joined: 07/09/2014 Location: United KingdomPosts: 71 |
Thanks! Yes, I am aware of those things. My goal was to build the absolute barebone system, making some assumptions on the way, of course. Using the internal pullups. I have tested with a few keyboards and monitors that I have and they all worked. Surely there might be some others that won't be happy, but it is a trade off for simplicity. Support for mouse I think is a bit pointless in a 64K mono machine. PS. I have some leftover boards from the previous revision. For free, I will only want the P&P. Always feeling bad if I need to throw away perfectly good PCBs. The only difference between the previous version and the current release is that it uses MCP1700-3302 which is a lower current LDO than the one in the current board. Edited 2021-02-26 22:38 by knivd |
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MauroXavier Guru Joined: 06/03/2016 Location: BrazilPosts: 303 |
What fantastic work! Someday I will put my "dirty" hands on it to make games... Don't say that... I believe it's possible to develop a Missile Command clone for this wonderful little machine. Mono isn't a problem at all, as you created great native line patterns. Edited 2021-02-26 22:56 by MauroXavier |
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lizby Guru Joined: 17/05/2016 Location: United StatesPosts: 2989 |
Very neat indeed. A better subject line might have given more clues and drawn more attention, something like: ELLO Computer with VGA and Small C Interpreter The C interpreter is, to my mind, a major accomplishment--a fuller implementation than my first C compiler--Ron Cain's Small C from the May 1980 issue of Dr. Dobb's Journal of Computer Calisthenics & Orthodontia. Kudos. Nice web site, too. I would indeed be interested in a board, and have PMed you. PicoMite, Armmite F4, SensorKits, MMBasic Hardware, Games, etc. on fruitoftheshed |
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Swartz Newbie Joined: 15/12/2020 Location: United StatesPosts: 18 |
knivd - This is a really neat project! It will be great fun to track it. When you declare it "ready for general release" I will grab up a couple to play around with. In the past I had written a C-like language interpreter but certainly *nothing that would embeddable* . Congratulations! Swartz |
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Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 5648 |
What a lovely little thing! I know sod all C though. lol Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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mclout999 Guru Joined: 05/07/2020 Location: United StatesPosts: 430 |
It is like a simplified CMM1 mono with C? Is that a good approximation? Not a lot of GPIO available and what kind of Expansion is planned or possible? |
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lizby Guru Joined: 17/05/2016 Location: United StatesPosts: 2989 |
What additional circuitry would be required to achieve the suggested protection? PicoMite, Armmite F4, SensorKits, MMBasic Hardware, Games, etc. on fruitoftheshed |
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matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 8517 |
Inline resistor into a diode - see the CMM1 circuit on Geoff's site |
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knivd Regular Member Joined: 07/09/2014 Location: United KingdomPosts: 71 |
Yes, that is a close approximation. The lack of GPIO really comes from the MCU package. That PIC32 is currently the most powerful through-hole MCU on the market. In terms of expansion, I am yet to complete the <platform.h> library with functions for I/O and comms. Then, the first expansions could be an RTC clock (the expansion header is already compatible with one such popular option on Aliexpress), and maybe a serial RAM expansion. |
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knivd Regular Member Joined: 07/09/2014 Location: United KingdomPosts: 71 |
Yes, that would be the correct one. I even had it in the earliest board, but then discovered that the three monitors I have for testing all have their own internal protection and apparently that is a common thing, so the schematic became two components lighter. It is of course very easy to add them back but it would be mostly to deal with some corner cases. |
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zeitfest Guru Joined: 31/07/2019 Location: AustraliaPosts: 369 |
Is there an ascii serial i/o , ie instead of using the keyboard and vga ? |
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knivd Regular Member Joined: 07/09/2014 Location: United KingdomPosts: 71 |
Not yet implemented. It is quite easy but low on my list of tasks because that invalidates the main point of the board |
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Frank N. Furter Guru Joined: 28/05/2012 Location: GermanyPosts: 813 |
Hi Kon, I just read about your great project - do you have a PCB left? THANKS! Frank |
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knivd Regular Member Joined: 07/09/2014 Location: United KingdomPosts: 71 |
I just read about your great project - do you have a PCB left? THANKS! Frank PM me to discuss. |
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zeitfest Guru Joined: 31/07/2019 Location: AustraliaPosts: 369 |
Not yet implemented. It is quite easy but low on my list of tasks because that invalidates the main point of the board I know it is not your aim, however I would encourage you to make your C interpreter available via a serial i/o...maybe squeeze a mcp2221a on the board, or make it run on the serial i/o-based boards available. I think there is a lot of demand for it, a small embedded C board that did not need compiling would be very useful I think, and using a PC for the writing bypasses editors displays etc and makes it cheaper. |
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