STE: What are these jumpers?

[flashjazzcat]

I just got hold of a very nice 520STE for £6.49 which has cleaned up up like new:

PCB.jpg

However, I'm wondering what these jumpers and the piggy-backed IC are for?

The only fly in the ointment is the buggy DMA chip, so I'll need a revised one otherwise Ultra Satan is a no go...

[Nyh]

However, I'm wondering what these jumpers and the piggy-backed IC are for?

It looks like the timer A interrupt port is clocked with a new clock speed. I don't know exactly which because I don't know what the chip the 74LS16 is piggy backed on is supposed to do. I expect it be an counter so the 2MHz clock is divided to xxx kHz.

Hans Wessels

[simbo]

this is a missprint to the pcb

and is a factory addition
to a screwed up pcb /schematic error

simply ignore this ic its supposed er not supposed to be there

i have one to as does every ste .... pre rev d pcb

its a late addin to correct a sound chip problem if i remember on boot....

if you have above 1mb ram...

[flashjazzcat]

Thanks for the info guys. Next job is to find a replacement DMA chip. I've put the feelers out but nothing yet...

[simbo]

have you tested the dma chip first!!!

the same number dia exactly can perform perfectly
its all down to where it was manufactured ive found
if its a PH on it anywhere its ok ph with a ring round it is usualy on the underside
if its a malay in a ring or MA on it maybe its one of the dia set ... thats got a small flaw
but check the number on the top first for the type that has the problem... numbers...
youll find this in other posts... even ive made

dont just change it check it first when you have a satandisk
atleast youll know to change it if you encounter a problem anyway
without trying to find one first
best in the u/s have a good stock of the later ic im sure...!!!!
ive found them quite helpfull... but tight with there prices { i dont blame them}

if i remember this flaw only appears with the cubase low level scsi driver

and doesnt apply to hddriver v8 and above as he wrote his own to work around this and other errors

cmiiw

[insanity]

Hey flashjazzcat,

Any chance of a full picture of your motherboard for our Wiki whilst the ST is open?

Post here: http://www.atari-forum.com/viewtopic.ph ... 6&start=20

or direct to the wiki here: http://www.atari-forum.com/wiki/index.p ... _revisions

Thanks

baz

[Chandler]

this is a missprint to the pcb

and is a factory addition
to a screwed up pcb /schematic error

simply ignore this ic its supposed er not supposed to be there

i have one to as does every ste .... pre rev d pcb

its a late addin to correct a sound chip problem if i remember on boot....

if you have above 1mb ram...

interesting you say about the sound chip error on boot Simbo

would this apply to my STE mobo in my thread?

[simbo]

dow know
look for the piggy back ic

look above to the picture this is a factory add in

it was one of the first posts i made way back in 2003
i didnt know what it was the ste i picked up had
i had never seen it and im sure someone said it was something to do with sound chip init
elfacto reverso something to do with sound on boot or and reset....

[flashjazzcat]

Hey flashjazzcat,
Any chance of a full picture of your motherboard for our Wiki whilst the ST is open?

No problerm; I'll pop the top off again over the weekend and upload some images.

Interesting to note there's some debate over whether or not the earlier DMA chip will cause problems. All my information is based on this article:

http://www.notator.org/html/notator_faq.html#DMA_STe

There's very little other information on the web - even in the forums - about the DMA problem.

Edit... Simbo I've just perused some of your older posts on this topic. It seems one may or may not have problems when the time comes, as you say.

[MRAtari]

you may get problems with that DMA , you may not

i had an STE with a dodgy DMA and it corrupted an SH205 Atari branded hard drive

depends if you wanna take the risk and wait till it happens to yours

the fact is Atari thought it a problem enough to change the chip