Creating ROM chips

[ralcool]

Nice Atari Ralcool. Is that ram on the mainboard or on the edge of the exrea pcb on top?

Well both. The original 16 are disabled holding ras and cas high.

The simm takes the data lines from the pcb from the video shifter chip, and the address lines are hard wired back to the resisters from the mmu.
memory management unit wot is a black square under the cpu mounted address decoder for the OS roms and the ide interface.

awesome. Also has HD 1.44Mb floppy drive.

[psyolent]

noice.
thanks joe re: Actually, NiMH are 1.2/1.25V per cell (pretty much like NiCd), not 1.5V, so you still need 3 cells like the original.
also thanks re : verdigris. i'd have never googled the shit out that but ; makes sense.
i'm actually going to remove the battery of death and put a button cell battery with diode to stop the thing from charging upstream of it. be gone battery of death.

check this shit out on the main IDC header

alas things are not well with the old bird ; i replaced the fan in the PSU today as that was toast. so thats come back to life ; but ; i get a black screen of death which normally means the CPU is not seated. i've re-seated it but still to no avail. the battery of death is near the end of the 68K so not sure whether i'll resocket it/buzz it out.

[antus]

Have you got a scope (usb)?

[psyolent]

antus................no. too many out there never made up my mind on which one to get. my mate just got a pico 2204 which he loves.

[psyolent]

that and the fact i got no idea on how to use one. sure youtube can fix that

[antus]

Ive got an old hantek one, its pretty good. What it is good for is that you can see the quality and amount of electrical noise on the power lines. Since you've had PSU problems its possible that the psu is providing poor quality power and thats hard to test with a regular multimeter.

Having said that, theres a thousand other things it could also be, of course including tarnished connectors on any of the chips that are socketed or damaged chips if they've been over voltaged. Is any chip emitting a suspiciously large amount of heat?

[psyolent]

yes, very true..............nup i've done the feely feely test. nothing overly warm on there.
i have a sneaking suspicion the 68k chip is dead. i have an empty mainboard to test it in which is known good so not an issue.

[ralcool]

http://www.atari-forum.com/viewtopic.php?f=15&t=30280

http://www.chzsoft.de/asic-web/

One of the members of our forum unlocked a bag of secrets recently of the Atari.

Basically a rare glimpse into the internal workings of custom chips.

[vlad01]

Lol some obscure format?

Dwg is just native autocad format. It will be a vector based drawing.

[ralcool]

Ahh, no it wasn't apparently. Was mentioned footnote #2.