QFP Cx586 and Am5x86 transplants are up next in my pipeline. Hope my 1 year old solder paste is up to the task. I kept it in the fridge.
Plan your life wisely, you'll be dead before you know it.
feipoa wrote on 2025-09-24, 08:23:QFP Cx586 and Am5x86 transplants are up next in my pipeline. Hope my 1 year old solder paste is up to the task. I kept it in the fridge.
Ugh, I wish. Despite my efforts I have been able to locate exactly zero of any suitable interposers, seems like any supply from China has dried up. Tearing apart a working one with an AMD is just not in the budget. It makes me wonder if a motherboard with pads for a qfp 486dx would be a suitable candidate. At one point I owned an ATC-1415 that has these - It was pretty decent board, the only issue I remember it had was also having a hole in the cacheable range 56-64mb like some others with similar bioses do. I wonder if I obtained another if I could make that qfp cyrix work on it. Unfortunately, I have never seen a photo of one of these with a qfp actually in place to compare - I imagine that the boards sporting a socket 3 (all of them?) may be missing a few parts necessary for the qfp to work which may make things more complicated
bertrammatrix wrote on 2025-09-30, 17:13:feipoa wrote on 2025-09-24, 08:23:QFP Cx586 and Am5x86 transplants are up next in my pipeline. Hope my 1 year old solder paste is up to the task. I kept it in the fridge.
Ugh, I wish. Despite my efforts I have been able to locate exactly zero of any suitable interposers, seems like any supply from China has dried up. Tearing apart a working one with an AMD is just not in the budget. It makes me wonder if a motherboard with pads for a qfp 486dx would be a suitable candidate. At one point I owned an ATC-1415 that has these - It was pretty decent board, the only issue I remember it had was also having a hole in the cacheable range 56-64mb like some others with similar bioses do. I wonder if I obtained another if I could make that qfp cyrix work on it. Unfortunately, I have never seen a photo of one of these with a qfp actually in place to compare - I imagine that the boards sporting a socket 3 (all of them?) may be missing a few parts necessary for the qfp to work which may make things more complicated
I have had several 486sx chips on qfp to pga adapters that came in OEM branded systems.
If your motherboard allows voltage adjustment they “should “ work
rmay635703 wrote on Yesterday, 03:33:bertrammatrix wrote on 2025-09-30, 17:13:feipoa wrote on 2025-09-24, 08:23:QFP Cx586 and Am5x86 transplants are up next in my pipeline. Hope my 1 year old solder paste is up to the task. I kept it in the fridge.
Ugh, I wish. Despite my efforts I have been able to locate exactly zero of any suitable interposers, seems like any supply from China has dried up. Tearing apart a working one with an AMD is just not in the budget. It makes me wonder if a motherboard with pads for a qfp 486dx would be a suitable candidate. At one point I owned an ATC-1415 that has these - It was pretty decent board, the only issue I remember it had was also having a hole in the cacheable range 56-64mb like some others with similar bioses do. I wonder if I obtained another if I could make that qfp cyrix work on it. Unfortunately, I have never seen a photo of one of these with a qfp actually in place to compare - I imagine that the boards sporting a socket 3 (all of them?) may be missing a few parts necessary for the qfp to work which may make things more complicated
I have had several 486sx chips on qfp to pga adapters that came in OEM branded systems.
If your motherboard allows voltage adjustment they “should “ work
I initially thought this as well, however unfortunately 486sx comes in a qfp with less leads then a qfp 486dx2/4/5x86 has, making the interposers unusable for those CPU
486SX has a different pin out and pin count.
I sent a follow-up about the interposers, but don't get your hopes up.
Maybe you can assemble one of RayeR's interposers?
Plan your life wisely, you'll be dead before you know it.
feipoa wrote on Yesterday, 08:58:486SX has a different pin out and pin count.
I sent a follow-up about the interposers, but don't get your hopes up.
Maybe you can assemble one of RayeR's interposers?
Are these the interposers?
https://rayer.g6.cz/hardware/retropc2.htm#486DX5_INTERPOSER
https://rayer.g6.cz/hardware/retropc2.htm#486 … 5_INTERPOSER_V2
Ya, that's it. There's a post about this interposer somewhere on VOGONS but I'm having trouble locating it. I think it has 6 A VRM.
The Chinese sourced interposers you see in the above photo are on the noisier side with respect to Vcc.
120 mV noise without any caps
60 mv noise with 2x10 uF tantalum and 4x100 nF ceramic
whereas with the IBM Thinkpad interposer you see in the photo, 16 mV. I'm going to try increasing the tantalums from 10 uF to 100 uF to see if it helps any.
Plan your life wisely, you'll be dead before you know it.
