Search found 25 matches

by Tiger
Fri Apr 02, 2021 8:41 pm
Forum: Hardware
Topic: Fault ZX Spectrum 48k
Replies: 5
Views: 392

Re: Fault ZX Spectrum 48k

I also think it is a faulty upper-RAM. ;)
by Tiger
Sun Feb 14, 2021 4:35 pm
Forum: Hardware
Topic: Spectrum 48K Upper Ram Fault
Replies: 22
Views: 1502

Re: Spectrum 48K Upper Ram Fault

Thank you Mark - that's what I meant
by Tiger
Sat Feb 13, 2021 3:30 pm
Forum: Hardware
Topic: Spectrum 48K Upper Ram Fault
Replies: 22
Views: 1502

Re: Spectrum 48K Upper Ram Fault

@hatman72 I think the answer is in the second sentence of point 5 in Table 1: "Provided there is only one faulty ic at the address". I think there is more than one of the IC's out of order so the PEEK's and POKE's are not very helpful. A other problem I've found on some Speccy's are "perfect" solder...
by Tiger
Sat Feb 13, 2021 12:06 pm
Forum: Hardware
Topic: Spectrum 48K Upper Ram Fault
Replies: 22
Views: 1502

Re: Spectrum 48K Upper Ram Fault

@gozzo - you can also use 256-RAM's. I'd fixed some Speccys with NEC D41256C, OKI M41256A (always the same refresh cycle) without any problems. ;)
by Tiger
Sat Feb 13, 2021 1:18 am
Forum: Hardware
Topic: Spectrum 48K Upper Ram Fault
Replies: 22
Views: 1502

Re: Spectrum 48K Upper Ram Fault

Perfect - you really got an probably faulty Speccy 👍 For the upper RAM fault it is possible that one or more of the IC15-IC22 are damaged. The best solution is to replace all with new RAM's which must all be of the same type. The other way is to swap them one by one and look if the value of the "PRI...
by Tiger
Sat Jan 30, 2021 11:14 am
Forum: Hardware
Topic: Spectrum+ 128K ToastracK RAM faults?
Replies: 5
Views: 902

Re: Spectrum+ 128K ToastracK RAM faults?

It is also possible, that there is a problem with the contact between expansion bus and smartcard, so the test on an other Speccy doesn't help very much...
by Tiger
Sat Jan 30, 2021 10:48 am
Forum: Hardware
Topic: Spectrum+ 128K ToastracK RAM faults?
Replies: 5
Views: 902

Re: Spectrum+ 128K ToastracK RAM faults?

IC 29 (a PAL-IC which must be programed) controls memory accesses in conjunction with Z80 and ULA. In the case you didn't swap any RAM's between the tests, there could be a mistake in this area. RAM-test should also be possible without the adapter at the expansion bus. Do you have the same result wi...
by Tiger
Mon Jan 18, 2021 8:16 pm
Forum: Spectrum BASIC
Topic: Decimal Value
Replies: 8
Views: 3111

Re: Decimal Value

I tried it with an Harlequin 128. With 128k-Basic and also 48K Basic it seems to work, but with "PRINT test" I receive "299793". Is this "round-function" the problem?
With "PRINT test - 1.099" I receive "299791.9" so it seems the variable "test" is correctly stored.
by Tiger
Sat Jan 02, 2021 6:59 pm
Forum: Hardware
Topic: 2 red lines on the screen
Replies: 9
Views: 589

Re: 2 red lines on the screen

looks very mysterious - is it possible to try it with an other monitor or tv? The red lines are looking so perfect - much clearer than the "NEW" prompt :ugeek:
by Tiger
Sun Nov 22, 2020 12:02 am
Forum: ZX Spectrum Lounge
Topic: 128k +2 Mysterious Videos issue.
Replies: 36
Views: 9388

Re: 128k +2 Mysterious Videos issue.

:( - random pattern - looks like (Upper-)RAM damage :shock: