[quote="rich_chandler;923345"]https://www.wikipedia.org/wiki/ZX_Spectrum_Contended_Memory[/quote]

Okay so the ULA stops the z80 clock signal, but can't this be worked around, e.g. by adding a separate clock source?

... the ULA stops the z80 clock signal, but can't this be ... .g. by adding a separate clock source?[/quote]
It is ... external video RAM. The video signal should also be generated in ...

... from low to high.
Clock signal is ok too and reaches ... feed the spectrum a valid clock from another spectrum? It does ... a lot more than just clock right?

... timing, including providing the CPU clock signal
[*]Generate the screen display ... that the Z80 has a clock and is not being held ...

... somewhat mitigated by the buffered clock signal mod which was done at ...

... Spectrum model
Independent of clock signal
Two configurable joystick ports ...

... +2A) boards have the CPU clock driven by the gate array ... to invert the inverted CKEXT clock for the CPU with R45 ... and there (one on the clock signal and one on a data ...

... and there (one on the clock signal and one on a data ... are the C53 on the clock line next to the inverter ...

... factory to buffer (delay?) the clock.[/quote]
Let me get ... is created by routing the clock signal through an additional inverter of ...

... have!).

With the clock signal it's not clear whether ... the signal does suggest they're trying to delay the clock edge ...

[quote="guesser;927803"]With the clock signal it's not clear whether ... the signal does suggest they're trying to delay the clock edge ...

... the AY get it's clock signal from the CPU though? So ...

... the AY get it's clock signal from the CPU though? So ... , so other than the different clock speeds, I don’t see ...

... custom chip is defective. No clock signal is sent to the CPU ...

... I can get a decent clock signal from the z80 with my ...

... joysticks (they got an extra clock signal and will report different state ... depending on that clock). They are supposed to be ...

Curious. The ULA generates the clock signal and it reaches the CPU. ...

... before?
Even without the clock signal reaching the CPU, the ULA ... C42 generate the V. SYNC signal, so you might be right ...

[quote="cj7hawk;975204"]No clock on the z80. Check at the oscillator. 17.27MHz. [/quote]
Hold on. If the CPU is getting no clock, then the problem might be the ULA. Check Pin 36. You should see a steady 3.5 MHz clock signal there.

... 's 3.5MHz clock.

Clock *dividers* are easy ... want to multiply the signal by. If you want ... signal that is kept in sync with the 4MHz master clock ... bottom is the 4MHz reference clock.

[ ... which is the reference clock. (The two capacitors ...

... both the TV signal and the composite signal taken from the monitor ...

... on it via a composite signal. I know you can modify ... 48k and get a composite signal from the RF modulator but ... you can get a composite signal from the edge connector and ... to the fact that the signal from the edge connector isn ...

... . On TV there is no signal of any kind. Almost there ... ). If there is no TV signal from speccy I assumed that ...

... created a theme with swf clock :

[url]http://www ... title screen there appear digital clock with seconds.

... very soon the analogue TV signal will be turned off, next ... still: a very early digital clock, built from relays and uniselectors ...

... to supposedly provide RGB SCART signal - these cables are from ... rgbcgatovgac.html[/url]
Signal Requirements:
RGB: 0.7Vpp ... when SCART devices display composite signal, but not when using ... maybe the final SCART signal levels are different between ...

... IIRC). Basically, if the reset signal from the Spectrum rises at ... as the W5100's 25MHz clock, the chip fails to autonegotiate ... 150 resets if your reset signal rises quickly. However, the ... Spectrum reset signal rises very slowly, so it ...

Anyone tried tuning in their speccies now the analogue signal has gone? Has it improved?