256K x 1 bit dram ICs are easier to get and problem is 1M x 1bit very hard to find in DIP package and either way, very expensive to obtain.

I have same problem right now and I cannot find any sources to get 1M x 1bit 80ns or 70ns for my compaq Kingston expansion card conversion from 1MB to 4MB.

286 can take either 120ns or 100ns dram ICs due to generic motherboard and loose timing.

Cheers,

Cross reference for 256k X 1

https://ibm.retropc.se/memory/41256/41256_list_1.pdf
https://ibm.retropc.se/memory/41256/41256_list_2.txt
https://ibm.retropc.se/memory/41256/41256_list_3.pdf
https://ibm.retropc.se/memory/41256/41256_list_4.jpg
https://ibm.retropc.se/memory/41256/41256_list_5.jpg
https://ibm.retropc.se/memory/41256/41256_list_6.jpg

And 1024x1

https://ibm.retropc.se/memory/41256/41256_list_6.jpg
https://ibm.retropc.se/memory/41256/41256_list_4.jpg

THE LIST

MB81C1000 , GM71C1000, HM511000, HY531000, MT4C1024, M5M41000, MCM511000, UPD421000, MSM511000, km41C1000, TMS4C1024, TC511000

€ 3,13 is a good price for 9 chip GM71C1000-80 ?

Absolutely! (Even for just a 1MB simm)

pentiumspeed wrote on 2021-04-05, 23:56:

256K x 1 bit dram ICs are easier to get and problem is 1M x 1bit very hard to find in DIP package and either way, very expensive […]
Show full quote

256K x 1 bit dram ICs are easier to get and problem is 1M x 1bit very hard to find in DIP package and either way, very expensive to obtain.

I have same problem right now and I cannot find any sources to get 1M x 1bit 80ns or 70ns for my compaq Kingston expansion card conversion from 1MB to 4MB.

286 can take either 120ns or 100ns dram ICs due to generic motherboard and loose timing.

Cheers,

To partially solve the problem I made myself this adapter, disassembling a 1Mb simm and patiently reassembling the chips on the adapter, as soon as I get the 286 card I will test them

Would love to try and build my own , to test on my Turbo M1011 Acer board

dataino.it wrote on 2021-05-14, 19:32:

pentiumspeed wrote on 2021-04-05, 23:56:

256K x 1 bit dram ICs are easier to get and problem is 1M x 1bit very hard to find in DIP package and either way, very expensive […]
Show full quote

256K x 1 bit dram ICs are easier to get and problem is 1M x 1bit very hard to find in DIP package and either way, very expensive to obtain.

I have same problem right now and I cannot find any sources to get 1M x 1bit 80ns or 70ns for my compaq Kingston expansion card conversion from 1MB to 4MB.

286 can take either 120ns or 100ns dram ICs due to generic motherboard and loose timing.

Cheers,

To partially solve the problem I made myself this adapter, disassembling a 1Mb simm and patiently reassembling the chips on the adapter, as soon as I get the 286 card I will test them

Here are the KICAD files

ryanfox81 wrote on 2022-07-14, 13:46:

Would love to try and build my own , to test on my Turbo M1011 Acer board

dataino.it wrote on 2021-05-14, 19:32:

pentiumspeed wrote on 2021-04-05, 23:56:

256K x 1 bit dram ICs are easier to get and problem is 1M x 1bit very hard to find in DIP package and either way, very expensive […]
Show full quote

256K x 1 bit dram ICs are easier to get and problem is 1M x 1bit very hard to find in DIP package and either way, very expensive to obtain.

I have same problem right now and I cannot find any sources to get 1M x 1bit 80ns or 70ns for my compaq Kingston expansion card conversion from 1MB to 4MB.

286 can take either 120ns or 100ns dram ICs due to generic motherboard and loose timing.

Cheers,

To partially solve the problem I made myself this adapter, disassembling a 1Mb simm and patiently reassembling the chips on the adapter, as soon as I get the 286 card I will test them

The Male-Male connector
https://it.rs-online.com/web/cp/6742523,67425 … 252FT&sra=p&r=t

the result

test

You decided to go for DIPs and adapters rather than SIPPs? Was it somehow easier to get the SIMMs, remove the chips and adapt them to DIP sockets?

timw4mail wrote on 2022-07-14, 17:47:

You decided to go for DIPs and adapters rather than SIPPs? Was it somehow easier to get the SIMMs, remove the chips and adapt them to DIP sockets?

No that was only the card on which to do the functional tests I used them on other cards where there were no alternatives. o 36 original ram chips for 40-50 euros, or adapters with 0.5 € per chip (since I have removed the rams from faulty SIMMs)

dataino.it wrote on 2022-07-14, 19:16:

timw4mail wrote on 2022-07-14, 17:47:

You decided to go for DIPs and adapters rather than SIPPs? Was it somehow easier to get the SIMMs, remove the chips and adapt them to DIP sockets?

No that was only the card on which to do the functional tests I used them on other cards where there were no alternatives. o 36 original ram chips for 40-50 euros, or adapters with 0.5 € per chip (since I have removed the rams from faulty SIMMs)

So, you had the SIMMS, and that was easier than getting SIPPs?

timw4mail wrote on 2022-07-15, 13:27:

dataino.it wrote on 2022-07-14, 19:16:

timw4mail wrote on 2022-07-14, 17:47:

You decided to go for DIPs and adapters rather than SIPPs? Was it somehow easier to get the SIMMs, remove the chips and adapt them to DIP sockets?

No that was only the card on which to do the functional tests I used them on other cards where there were no alternatives. o 36 original ram chips for 40-50 euros, or adapters with 0.5 € per chip (since I have removed the rams from faulty SIMMs)

So, you had the SIMMS, and that was easier than getting SIPPs?

He already said he used that board with the sipp & DIP sockets for testing.