DMA ISSUE ON H4

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exxos
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Re: DMA ISSUE ON H4

Post by exxos »

HDCS was used on the H4... The PCB breaks that line and from FDCS goes via the inverter to the 245 instead.. Its pretty simple.
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viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
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rubber_jonnie
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Re: DMA ISSUE ON H4

Post by rubber_jonnie »

@Icky Awesome, thanks. Inverter is on order so I'll hopefully be able to get this done soon, though I am away for a few days from Sunday, so I may have to wait until the following weekend.
Collector of many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
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rubber_jonnie
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Re: DMA ISSUE ON H4

Post by rubber_jonnie »

exxos wrote: Wed Mar 11, 2020 11:43 pm HDCS was used on the H4... The PCB breaks that line and from FDCS goes via the inverter to the 245 instead.. Its pretty simple.
@exxos Cool thanks, looks like I understood it correctly 😁
Collector of many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
Tomswork
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Re: DMA ISSUE ON H4

Post by Tomswork »

Got an email from osh saying the dma fix boards they shipped me are defective and new ones will be shipped soon err.

Tom
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rubber_jonnie
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Re: DMA ISSUE ON H4

Post by rubber_jonnie »

Hoping my inverters will be there when I get home later today. I decided not to order pcbs for the DMA fix in the end, as apart from the inverters I have enough proto board around to make them. I guess we'll see later.
Collector of many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
troed
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Re: DMA ISSUE ON H4

Post by troed »

:/

Got the patch board from exxos of course, but the 74LVC1G04 isn't in the BOM and I don't have one at hand.

I should've read up on all the threads before ordering the components.

/Troed
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PhilC
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Re: DMA ISSUE ON H4

Post by PhilC »

@troed yeah I did the same but it gave me an excuse to order more goodies at the same time as the 04.
If it ain't broke, test it to Destruction.
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JezC
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Re: DMA ISSUE ON H4

Post by JezC »

troed wrote: Thu Jun 11, 2020 9:57 pm Got the patch board from exxos of course, but the 74LVC1G04 isn't in the BOM and I don't have one at hand.

I should've read up on all the threads before ordering the components.

/Troed
Good job you mentioned it...need to add 2x of those to my next order as well...
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Robson
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Re: DMA ISSUE ON H4

Post by Robson »

Does anybody have a spare fix board by any chance? DoG was able to help me out for the first board but since I'm about to finish another one, I'd like to have a clean install and tought somebody might have an extra. I'll cover the costs (i'm in the UK) but rather not wait for a new batch of pcbs just for 1.
Let me know, thanks.
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Icky
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Re: DMA ISSUE ON H4

Post by Icky »

@Robson - I have one with the SMT chip already installed. PM me :)
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