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Tiny 'XT-class' machine

Defiant1Dave

Member
Joined
Sep 27, 2011
Messages
48
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gone, baby
That has got to be the coolest project I've seen in a long time! I can think of a LOT of things to do with that baby! As soon as they are available, I want one.
 

basman74

Experienced Member
Joined
Feb 16, 2010
Messages
124
The end of the road..

The end of the road..

Dear all,

Due to the non-availability of the chip used in Flea86, I am formally announcing the end of this project.

I would like to thank those who helped me with this project, as well as those few who literally twisted my arm to obtain a tested/working Flea86 board. This in spite of my reluctance to continue due to the arrival of solutions like raspberry pi etc. Many thanks :)

Regards Valentin
 
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basman74

Experienced Member
Joined
Feb 16, 2010
Messages
124
RE: x86 emulation on an 8052

RE: x86 emulation on an 8052

Hi Valentin!

You did an amazing job with that 8052--far more than I would have thought was possible. Thank you for your hard work.

Well it's all academic now I guess, but I learned quite a few things though it along the way. Not least of which was due to your expert input, thanks Chuck. :)

If I were to be involved in another indie x86-based project again, I would possibly look into porting the Zet x86 project source to a new homebrew board I'm tinkering with:

Flea2v40_small.jpgIts_alive_screen.jpg

Regards Valentin
 

mbbrutman

Associate Cat Herder
Staff member
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May 3, 2003
Messages
6,386
I have been terribly preoccupied with real life the past two years but the Flea86 was one of the pleasant distractions. My small contribution is that some of my code was used to flush out bugs in the emulation.

If you think about it most of us get excited when somebody does a cool demo, a small hardware project, or some useful software. Valentin created an entire computer system on a small board. And he designed it to use an emulation layer such that the very architecture of the machine which you emulated could be changed within a few seconds. Don't like the Tandy 1000 emulation? Load the EGA code instead. Or even emulate an Apple ][. The design, implementation and software all came from Valentin - very few people can do all of that.

Some of the neat things:

  • PS/2 and VGA ports which most of us have hardware for. No CGA or EGA monitors required.
  • FLASH based storage; tiny and no moving parts
  • System flexibility: the emulator left a lot of room for configuration or even architecture changes
  • Amazingly good emulation; enough to run games, Windows, etc.

And there were some warts:

  • It is an emulator, not a perfect simulation the actual hardware. Some things were different. Some things were missing outright.
  • Valentin ... he needed to clone himself a few more times to have the bandwidth to realize the potential.
  • The AX-2005. It was just a little too cramped. Lack of addressability was forcing some compromises.

I have an early prototype and one of the uber-rare ISA bridge boards which allows some of the simpler ISA cards to run. I used the bridge board to enable networking on the Flea86. It was not a great FTP server, but it was a riot to show people. I need to update my review of the Flea86 to show the board; it is obsolete now but it is still verycool.

I think Valentin is onto something better with his later designs. The RaspPi is a very good small embedded Linux system but by the time you are calling a system that runs Linux embedded you are quite far away from the hardware. A simpler design that can change instruction sets with minimal fuss can be a really cool tool for learning computer science at a very low level.
 

basman74

Experienced Member
Joined
Feb 16, 2010
Messages
124
My small contribution is that some of my code was used to flush out bugs in the emulation.

MTCP is among the best software I've seen run on legacy x86 hardware of late - so I was really pleased to see that running on Flea86. Thanks for your help!

The AX-2005. It was just a little too cramped. Lack of addressability was forcing some compromises.

Writing a firmware update package for that chip was one of the many tough problems I had to sort out with this project (not entirely the chip's fault btw - I used a multiplexed external data bus design which also gave trouble). By the time I'd solved the vast majority of problems, the world had moved on..
 
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Mike Chambers

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Sep 2, 2006
Messages
2,621
My small contribution is that some of my code was used to flush out bugs in the emulation.

Same, I also was able to help him fix a bug. I came across a bug in my emu Fake86 almost 2 years ago where it would hang on certain x87 FPU escape codes, and found Valentin had the same problem on the Flea86. I realized both of us were not parsing the addressing mode byte after the escape codes, and it sometimes caused the program counter to get misaligned. :)



If you think about it most of us get excited when somebody does a cool demo, a small hardware project, or some useful software. Valentin created an entire computer system on a small board. And he designed it to use an emulation layer such that the very architecture of the machine which you emulated could be changed within a few seconds. Don't like the Tandy 1000 emulation? Load the EGA code instead. Or even emulate an Apple ][. The design, implementation and software all came from Valentin - very few people can do all of that.

Yeah, what he did is extremely impressive no doubt.
 

basman74

Experienced Member
Joined
Feb 16, 2010
Messages
124
Same, I also was able to help him fix a bug. I came across a bug in my emu Fake86 almost 2 years ago where it would hang on certain x87 FPU escape codes, and found Valentin had the same problem on the Flea86. I realized both of us were not parsing the addressing mode byte after the escape codes, and it sometimes caused the program counter to get misaligned. :)

Heh, I'd forgotten about that. But I do recall you also giving me a leg-up with unchained Mode-13h VGA. Thanks!

By the way, well done for the effort on your Fake86 emulator - it has come a long, long way.. :D

For Flea86, hardest thing I had to sort out was working out a bit-banged solution for the planar EGA/VGA graphics modes. Those can be very difficult to get working right on modern computing hardware, let alone a souped-up 8042 keyboard controller... :(
 

cr1901

Veteran Member
Joined
Dec 28, 2011
Messages
817
Location
NJ
I can't believe I miss this thread... :(. Well, then again, I suppose there was nothing I could've done about that since the last post prior to announcing the end of the project was months before I joined.

Is it possible to emulate the out-of-production chip using an FPGA?
 

basman74

Experienced Member
Joined
Feb 16, 2010
Messages
124
Is it possible to emulate the out-of-production chip using an FPGA?

Well, given the AX-2005 ran at 150 and 200MHz that's still going to need an expensive FPGA due to the very short routing delays needed alone..

Best solution (if using an FPGA) is to recreate the x86-based processor and system logic instead. An excellent example of this is the Zet project (x86-based SoC).

I started a new project recently called FleaFPGA (http://www.fleasystems.com/fleaFPGA.html) which could implement an x86-based system (among other things). As soon as the forums over at zet.aluzina.org are working again I will make another request for some help..


Regards Valentin
 
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