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Re: ECB-DMA [message #8787 is a reply to message #8786]

Wed, 07 July 2021 03:44

lynchaj
Messages: 1080
Registered: June 2016

Senior Member

Hi Phillip

Another thought I meant to add but forgot was there are other IO peripherals which would benefit from a working DMA system. Somewhere earlier in this thread someone posted a partial ECB-SCSI-1 design with DMA support or something which could be adapted for DMA support. I looked at it a while ago and thought it needed some work but the point is once we have working DMA it will be worthwhile to revive and complete these designs for both PIO and DMA capabilities.

In addition, another project I'd like to see is a revival of the IDE from DiskIO board but this time modified for DMA support. I think that means a single IO port address so its probably a fairly significant modification but if we had IDE CF with DMA I think it would be dramatically better than PPIDE. Don't get me wrong, I think PPIDE is great but I don't think it can ever be anything but PIO only unless I am missing something. Please someone set me straight if I am wrong! However, I think a DMA capable CF-IDE would much better than current solutions.

Not a project we can do right now but something to consider down the road after the proof-of-concept are demonstrated to work successfully.

Thanks, Andrew Lynch

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Re: ECB-DMA [message #8806 is a reply to message #8735]

Thu, 08 July 2021 08:22

etchedpixels
Messages: 333
Registered: October 2015

Senior Member

b1ackmai1er wrote on Fri, 02 July 2021 02:06

not seeing any performance increase as previous posters predicted but it has added another blikenlight to to system

Raw I/O speed or through the CP/M ? If you are going through CP/M you won't see much because CP/M doesn't scale to modern I/O speeds - not that you can blame DRI for that! CP/M 3 is a bit better than 2.2 and at least tries to do direct to user I/O on bigger transfers if the program knows to do big transfers.

Alan

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Re: ECB-DMA [message #8825 is a reply to message #8806]

Fri, 09 July 2021 22:08

b1ackmai1er
Messages: 396
Registered: November 2017

Senior Member

Hi,

I have managed to verify that register reads now work and this has facilitated improving the driver to do hardware detection at initialization and return succcess/fail status on transfers.

Have submitted the driver to ROMWBW development build.

In regard to the circuit, is it ok to do this change? Is there anything special about B_IEI that makes this unwise to do?

/forum/index.php?t=getfile&id=2237&private=0

/forum/index.php?t=getfile&id=2237&private=0

Best Wishes Phil.

Attachment: dmaieibuffer.png
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Re: ECB-DMA [message #8843 is a reply to message #8825]

Tue, 13 July 2021 11:44

lynchaj
Messages: 1080
Registered: June 2016

Senior Member

Hi
I've stared at these circuit and they seem equivalent to me. The top U1A AND gate is essentially just an input buffer which is the same function as the 74ls244. the U1B AND gate is literally unchanged. Possibly the 74ls244 input has schmitt trigger inputs and the 74ls08 does not? I think if any difference the right hand circuit would perform better with a signal from the bus than the left hand circuit.

If they are not equivalent then they're pretty close, AFAIK. I'd like to see some of the other people's thoughts & opinions on the subject. I learn something most every time.

Thanks, Andrew Lynch

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Re: ECB-DMA [message #8916 is a reply to message #8843]

Thu, 29 July 2021 12:15

lynchaj
Messages: 1080
Registered: June 2016

Senior Member

Hi Phillip
OK, so the Z80 FDC seems to be working from my testing so that's good. Also drew up a Z80 DMA board based on the latest ECB-DMA. A few minor modifications for but nothing that should affect operations of the DMA logic. Mostly the "over the top" signal connector from the Z80 FDC and splicing in a few diagnostic LEDs. I'll post the design over on the Z80 MBC thread.

Thanks, Andrew Lynch

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Re: ECB-DMA [message #9816 is a reply to message #6745]

Mon, 14 March 2022 03:48

lynchaj
Messages: 1080
Registered: June 2016

Senior Member

b1ackmai1er wrote on Sun, 10 November 2019 03:16

Hi guys,

I have been working on reimplementing Wolfgang Kabtazke's ECB-DMA board.

https://www.retrobrewcomputers.org/doku.php?id=boards:ecb:dm a:start

I beleive this was prototyped but never finalized.

Kicad files have been regenerated and I have just finished routing the board in 10x10 format.

Would anyone be interested in building and debugging this board if I order some?

Regards Phil.

Hi

Well the good news is Phil realized Wolfgang's vision of an ECB-DMA board and it works. I ported the design over to Z80 MBC and it seems to work there as well. RomWBW supports DMA and even uses it to a limited extent with the Flash memory drive. It is nice to see the DMA board blinking away in my Z80 MBC systems.

However, there are still a lot of mysteries associated with this board and several things certainly would benefit from a more detailed explanation. I have a theory that Wolfgang designed this board based on a magazine article or a book. I don't see any references in the RBC wiki but this looks like something from the old C'T magazine (German) or something like that. Maybe an old hobbyist book?

Does anyone recognize this design from something they've read years ago? Does it look familiar in some way? It is possible that Wolfgang came up with this design entirely on his own so I don't discount that possibility either but I am guessing he was inspired by something. I think it would help if we knew what it was and could explain better how this board works.

Any ideas or thoughts on the topic? Thanks, Andrew Lynch

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Re: ECB-DMA [message #9837 is a reply to message #9816]

Wed, 23 March 2022 10:05

lynchaj
Messages: 1080
Registered: June 2016

Senior Member

Hi
Good news regarding the ECB DMA board. A very close derivative is the Z80 DMA board for Z80 MBC. Recently we found that the Z80 DMA board is able to do IM2 interrupts and coexist peaceably with other IM2 peripherals. This is excellent news because if it works on the Z80 DMA board it will likely work with the ECB DMA board as well. Wolfgang really designed an excellent DMA board. RomWBW supports Z80 MBC including the Z80 DMA board including IM2 interrupt support. The debugging software tool (DMAMON) was updated to include interrupt test function. Big Thanks to Wayne for his excellent work and support for RomWBW with the Z80 MBC

Thanks, Andrew Lynch

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