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Search found 191 matches

by Pr0f
Wed Jan 31, 2018 11:14 am
Forum: Hardware
Topic: All RAM chips destroyed??
Replies: 56
Views: 2949

Re: All RAM chips destroyed??

I think this is the issue 5 board - so no HAL chip, That does mean that the ZX8302 is on the same bus as the memory - so if that's faulty it may be causing problems... Yes it is exactly an iss5 board. So a faulty ZX8302 may cause RAM problems on an iss5 board and may work on an iss6 instead? I thou...
by Pr0f
Wed Jan 31, 2018 8:59 am
Forum: Hardware
Topic: All RAM chips destroyed??
Replies: 56
Views: 2949

Re: All RAM chips destroyed??

If touching the processor changes the screen output, then it could imply a lose pin in the socket, or it could be a capactive effect altering the oscillations of the crystal adjacent to the ZX8301 chip - the 15MHz crystal. Difficult to see in the picture - but has someone resoldered the resistor nea...
by Pr0f
Wed Jan 31, 2018 7:32 am
Forum: Hardware
Topic: All RAM chips destroyed??
Replies: 56
Views: 2949

Re: All RAM chips destroyed??

I think this is the issue 5 board - so no HAL chip, That does mean that the ZX8302 is on the same bus as the memory - so if that's faulty it may be causing problems...
by Pr0f
Tue Jan 30, 2018 11:29 am
Forum: Hardware
Topic: Naive question about SCART connection on TV
Replies: 21
Views: 970

Re: Naive question about SCART connection on TV

Hi ProF Not quite - the QL definitely provides TTL-level output on the RGB (and V / C-Sync) lines. My preferred reference on building a suitable SCART lead for the QL is here: http://www.fruitcake.plus.com/Sinclair/Spectrum128/SCARTCable/Spectrum128SCARTCableQL.htm I should go look a the circuit di...
by Pr0f
Tue Jan 30, 2018 11:27 am
Forum: Hardware
Topic: Naive question about SCART connection on TV
Replies: 21
Views: 970

Re: Naive question about SCART connection on TV

I believe the RGB outputs are 1V video on the 8 pin connector - as there are resistors on the motherboard between the socket and the video ULA. Actually not - seems the resistors are for the RGB encoder chip for composite / UHF signal output - the circuit board shows these are coming straight from ...
by Pr0f
Tue Jan 30, 2018 11:09 am
Forum: Hardware
Topic: Naive question about SCART connection on TV
Replies: 21
Views: 970

Re: Naive question about SCART connection on TV

I believe the RGB outputs are 1V video on the 8 pin connector - as there are resistors on the motherboard between the socket and the video ULA.
by Pr0f
Mon Jan 29, 2018 10:43 am
Forum: Software & Programming
Topic: Mice and mouse queues...
Replies: 11
Views: 661

Mice and mouse queues...

Firstly, forgive my ignorance, I may well be asking a question that you all know the answer to, but I don't know it. The question(s) relates to how the QL, or more specifically the pointer environment and SMSQ/E and the use of mice. I had some experience of PC mouse drivers and the concept of a mous...
by Pr0f
Fri Jan 26, 2018 2:14 pm
Forum: Software & Programming
Topic: QL Graphics
Replies: 34
Views: 1305

Re: QL Graphics

tofro wrote:.... And a picture that has most of its right-hand side flashing is probably not worth watching anyways...



Yes - agreed :-) - was trying to get my head around how harsh that might look as well. Definitely an edge case...
by Pr0f
Fri Jan 26, 2018 11:55 am
Forum: Software & Programming
Topic: QL Graphics
Replies: 34
Views: 1305

Re: QL Graphics

Flash must be in pairs - is that always true ? What if an entire line was to be set for flash, and somebody made use of the fact that flash would be reset at the end of the scanline - then you'd only have one flash bit set at the start of a line and no corresponding toggle off. In my opinion that co...
by Pr0f
Fri Jan 26, 2018 10:18 am
Forum: Hardware
Topic: Getting My QL working - what to do .....
Replies: 17
Views: 965

Re: Getting My QL working - what to do .....

Fristly - warm welcome to the forum :-) Some answers to your questions.... 1) Keyboard connectors - I take it you mean the two ribbon cable sockets on the motherboard ? If so you can get replacements - but soldering skills are required to remove and replace... Look on sell my retro - I think I saw s...

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