DMA ISSUE ON H4

[exxos]

I've been looking at the ACSI integration guides....

So CS is for command and data...

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and...

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BUT then...

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CS suddenly vanishes and no mention of it

I've not looked into this much, but seems to be some somewhat conflicting and incomplete information about all this

[czietz]

From the same document. Quite unambiguous.

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[Smonson]

The way I interpreted the document, _CS causes the peripheral to accept the command byte, which contains the ACSI device number, and only the device with that device number becomes selected. It then remains selected until the next command byte. All other peripherals that don't match the device number leave the bus alone.

[TimNaber]

After doing auto configure in the Tools menu it now sees the devices and partitions.

I read this and was going to mention: I found through trial and error that HDDriver.prg is a bit finicky when using a copy of the program after it has been set up for another machine. When doing so, you HAVE to AUTO-CONFIG, exit the program (so it can save your changes) and reboot. Then you get to see everything.

[Tomswork]

Just an ides on the 74ls245 74ls244 these are low power chips and produce a slow rise time vs current you could try 74hc244 and 74hc245 in there place and retest see if the profile improves

Tom

[exxos]

I will dump this fix PCB here so people can try it out.

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DMA_H4_FIX.zip

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[Icky]

I can confirm using an inverter on what was the HDCS line Pin 19 of IC6 and connection the other side of the inverter to FDCS it works. To test I copied a file from FDD to HDD and did the reverse and all was fine.

To get this to work I did a little hack by gluing a 74LS04 upside down on top of the 74LS245

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[exxos]

I can confirm using an inverter on what was the HDCS line Pin 19 of IC6 and connection the other side of the inverter to FDCS it works. To test I copied a file from FDD to HDD and did the reverse and all was fine.

Will add that fix onto the REV F

[btl]

I'm sorry, i don't understand the problem & solution here.

I bridged out the IC6 and it just works, but what purpose did IC6 have in theory? Keep signals strong?
If so, should i do the fix with the upside down 74LS04 or just keep it bridged?

Have a nice christmas all!
Greets,
btl

[Icky]

@btl - The H4 circuit is designed to have a buffer on the DMA to the ACSI bus which the STE has but not the ST. By jumpering over this basically is the ST circuit with no protection on the ACSI bus. The circuit was introduced on the STE and into the H4 to improve protection and against transfer collisions creating possible corruption on drives.