dont know if i can ask stuff about tandy if not remove it please
A friend has a tandy 1000 that Just died hé is looking for this chip ,buZing sound via speaker floppy drive les stays on no video via external card ,added a buffer buZing stops keyboard works but stil no life
any one in europe or outside knows where to buy this chip
That could be tricky, looks like it's a ~35 year old custom IC. Tandy 1000 SL service manual gives U41 as a 'Tandy Buffer Blue Custom IC Part #8079024' and it handles DMA, DRAM control, Data and Address bus buffering. I guess the 8079035 in your photo is an updated version, but I can't immediately find any old stock supplies for either part number.
All those functions can be handled discretely (unless it does more)
If you are an EE and can find data sheets and invest big time and $$$$ you could eventually build a board to replace that single chip.
Since you have a scope you could do some rudimentary tests, I’ve never seen it but sometimes only one function dies which would make emulation of a failed portion of the chip less difficult , although if one IC is dead others connected to it may also be failed.
Do you enjoy design and repair more than using the machine?
If not, time for a new machine , that ic could only be removed from another identical scrap system
Personally, I'd be aiming to get a known working motherboard to swap, unless scrap motherboard or mostly whole scrap machine was available very cheap. Do not do what I saw one guy on a Reddit group do with retro laptops the other year. He had one machine with a problem that looked good, one trashed looking machine that was cosmetically/mechanically falling apart but electrically running perfect... and instead of doing a complete motherboard swap in the first place, he transplanted component after component likely getting them all damaged by the suspected but ultimately unknown fault until he had two electronically broken machines.
Unicorn herding operations are proceeding, but all the totes of hens teeth and barrels of rocking horse poop give them plenty of hiding spots.
Looks like stuck reset circuit and is buzzing too?
Can you make sure this reset circuit is working correctly? Or power supply buzzing. Don't overthink over this. Start with basics.
Cheers,
Great Northern aka Canada.
You guys have to explain the things carefully and slowly so he can address this properly. I along with weedeewee had this situation with him when dealing the CONFIG.SYS and AUTOEXEC.BAT.
scroeffie wrote on 2021-09-23, 07:17:dont know if i can ask stuff about tandy if not remove it please
You are in the right place to ask this. 😉
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the tandy is not mine,iam asking for a friend 😀 but he wil add more info in the weekend
