DMA

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Msg : 270 of 326
From : Vitaly Kovalev 2:5020/400 Mon 22 Nov 99 17:06
To : All Thu 25 Nov 99 23:28
Subj : Re: DMA US H E L P !!!!!
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From: "Vitaly Kovalev" <el...@sura.com.ru>

Vitaly Kovalev writes in a message ...
>
>Hi All !!!
>We collected DMA the other day, and as they wrote in ADVENTURER 9 magazine
>the samples are cut off. There is a suspicion that the formation of the
>INT signal is happening somehow wrong. those. If you plug into the INT gap the circuit
>forming INT DMA, then the machine hangs dead. Some kind of rubbish rushes to the bus, and if you use the native INT, the samples are cut off.
>And for some reason the 36th leg (EOP) of the VT37 is hanging in the air. This signal should come from it to the INT formation circuit. but he doesn’t come.
>if instead of him 1 leg of D19 is pulled up to +5V, then the muse begins to play.
>and it’s quiet and quiet.
>And the developers for some reason clamped down on the INT debugging procedure, like wait in
>the next issue. :-(
>I don’t think the whole problem was that DMA is connected to Scorp with 1 meter
>of brains.512 kilos in it are built according to the Pentagon and up to 1 meter according to Profi.
>People, help whoever you can, otherwise it’s such a bummer.
>
>With respect, Vitaly.

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What can I say about this, is that the scheme by which the map was assembled is technically outdated - this can be seen immediately. The bug described in the letter may occur. because of the /EOP signal, a 10 kOhm resistor is attached to the 36th leg of the VT37 at +5, then /EOP goes to the INT formation circuit, to 1DD19. As for INT, the track is cut on the computer to the 6th leg of the Z80 (INT), with DMA the INT signal is fed to Z80, and the one that went there earlier - to DMA signal of the same name. The most reliable diagram + description of debugging
in the ECHO newspaper (the diagram has undergone some non-global changes). If any further questions arise, write or call.

85280 Mikhalchenkova D.A.
Yunosti st. 16\48
Kirovo village
Dzerzhinsk, Donetsk region
UKRAINE
TEL: 8+ (CODE OF DZERZHINSK DONETSKAYA OBL)+3-12-06, ask Andrey.

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Bye!
Pawel_...@mail.ru [ZX] [Real Software]