View Full Version : Amstrad 1640 boot up error

November 27th, 2017, 04:05 PM
I was using my Amstrad 1640 for about an hour, i turned the machine off and went outside for about 10 minutes. When i came back I turned the machine back on but when it started to boot from the dos disk, it crashed and kept scrolling " rity error)" down the screen. Not sure what could have caused this.

November 27th, 2017, 05:37 PM
Probably a truncated message that should say 'Parity Error' - my guess is bad RAM.

RAM on those is soldered in, so if you're going to bother changing it, change it all.

November 27th, 2017, 06:37 PM
I have another 1640 that had bad ram as well. I guess my luck with these isn't the best. On another note, how do you propose I check for the culprit or get some replacement chips?

November 27th, 2017, 06:41 PM
My 1640 had bad RAM too, and I couldn't be bothered fixing it so I eBayed it.

I'd just replace all the RAM. I can't remember the RAM type but it should be available on eBay.

November 27th, 2017, 06:49 PM
I'm probably the one who bought it. If it had the monitor, mouse, keyboard and a missing floppy drive.

November 27th, 2017, 07:30 PM
That does describe mine actually, are you in Melbourne? When I sold it it wouldn't even boot, just said 'Faulty System RAM'.

November 27th, 2017, 07:59 PM
I am indeed in Melbourne and it did say "Faulty System Ram." I also ordered a few chips, but they were quite pricey. Eventually i got it to display the "Please Wait" message but it would not continue to boot. Update on the current 1640 - I have been messing around with it for a while and now it will boot from the dos disk but if i try to do a command or look at the directory of another floppy it crashes and displays the message. Either the ram was still bad or the roms may have died.

Here is the Amstrad trying to boot (The old one)

November 28th, 2017, 01:56 AM
Ok, so i found the ram chips they are "km41256ap-12" chips. They are a little expensive so i'm wondering if you know of any substitutes?

November 28th, 2017, 02:54 AM
What do you mean by 'a little expensive'? That's really vague.

How many do you need?

November 28th, 2017, 12:09 PM
I have a second unit that i'm going to use for parts anyway but I was looking last night and I did manage to find 18 chips for about $56 total. Last time i bought some it was about $20 just for three.

November 28th, 2017, 12:54 PM
If you need some more let me know how many and I'll see if I have enough.

November 28th, 2017, 11:37 PM
I've found some very similar chips on ebay, they are "KM41256-15." The Amstrad had "KM41256-12" chips in it. These should work shouldn't they?

Here is the listing:
http://www.ebay.com.au/itm/5PCS-KM41256AP-15-256K-X-1-Bit-Dynamic-RAM-with-Page-Nibble-Mode-DIP16/321732623682?hash=item4ae8c23d42:g:q40AAOSwjVVVqLK 1

November 29th, 2017, 02:22 AM
the -12 and -15 are indicating the speed of the DRAM chip, a -15 is 150ns and the -12 is 120ns
So the 41256-15 might be too slow for you application.

On eBay there are plenty of of 41256-12 to be found if you enter that as search criteria.
The brand is of less importance as most of these chips were used in similar applications and fabricated to similar specs. But maybe others can chime in and prove otherwise.

November 29th, 2017, 02:35 AM
Just for clarification, Is the "KM41256-12" the same as the "KM41256ap-12"?

November 29th, 2017, 09:40 AM
Normally "P" denotes a plastic package, but I think in this case the "AP" denotes "page mode" available, so not the same, but should work...

November 29th, 2017, 01:59 PM
Ok, cool i'll order some later today. It probably will take a couple weeks as it's from France and i'm in Australia so this thread might be dead for a while.

November 29th, 2017, 02:08 PM
Good luck :)