Convert all the numbers to binary and you should see that in your test, bit 5 seems to be stuck high. Bit 5 in all upper RAM is provided by IC20 (the same one that I found to be faulty in the Spectrum I was repairing last night!).
In the first instance I'd recommend removing just IC20. The Spectrum should then always initialise as a 16K model. You should then run the memory test program I posted. It will, of course, immediately report errors, but it may discover some faults that haven't been revealed by the very simple POKE & PEEK test.
If it turns out you've got just one or two faulty ICs, then they can be directly replaced by 4164s (I believe one or two forum members regularly have some for sale). If you've got a lot of faulty upper RAM ICs, you might consider waiting for a bit as some time next month I should have an upper RAM version of these modules on sale.
ok , i already bought 4164 ram on Ebay to replace IC20 , i will make the test then.
I really apreciate all your help.
I will buy you a module when you have it.
Comments
117
170
In the first instance I'd recommend removing just IC20. The Spectrum should then always initialise as a 16K model. You should then run the memory test program I posted. It will, of course, immediately report errors, but it may discover some faults that haven't been revealed by the very simple POKE & PEEK test.
If it turns out you've got just one or two faulty ICs, then they can be directly replaced by 4164s (I believe one or two forum members regularly have some for sale). If you've got a lot of faulty upper RAM ICs, you might consider waiting for a bit as some time next month I should have an upper RAM version of these modules on sale.
In case of putting a upper ram module, do you send to Portugal?
Yes. Prices will probably be the same or very similar to those for the lower RAM module.
I really apreciate all your help.
I will buy you a module when you have it.
Thanks