Problem with H4 not booting (zChris's board)
Re: Problem with H4 not booting (zChris's board)
Just to be sure you're not using a DIP CPU *AND* a PLCC CPU ?
Re: Problem with H4 not booting (zChris's board)
Yeah, only have 1 CPU and thats PLCC.
/zChris
/zChris
Re: Problem with H4 not booting (zChris's board)
The image shows DIP CPU ?
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rubber_jonnie
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Re: Problem with H4 not booting (zChris's board)
I'm in agreement, the photo shows a DIP CPU present.
Collector of many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
Re: Problem with H4 not booting (zChris's board)
Ah alright, then its DIP.
/zChris
/zChris
Re: Problem with H4 not booting (zChris's board)
Alright, have done some measuring of frequency today. All the chips had signals present except MMU where i could not read a signal on Pin5 (16Mhz) and on Pin 19 and 20 it fluctuated between 2 and 4 Mhz. The measuring was done with the reset button NOT pressed in if that matters.
/zChris
/zChris
Re: Problem with H4 not booting (zChris's board)
After looking at https://www.exxosforum.co.uk/forum/viewt ... f=31&t=149 i saw that it was different pins on the SMD version of MCU (MMU) so after measuring again it i have found 4Mhz , 8Mhz and 16Mhz on that one aswell.
/zChris
/zChris
Re: Problem with H4 not booting (zChris's board)
You need to check ROM0,1,2 on the GLUE after reset .. But you need to put your scope in a one shot mode. I don't remember of hand where the setting is but without it you might miss the signals as they are very fast.
Re: Problem with H4 not booting (zChris's board)
Alright, what am i looking for on those lines ?
/zChris
/zChris
Re: Problem with H4 not booting (zChris's board)
They should be pulsing low. IIRC ROM should pulse first after reset.