Search found 9 matches

by john
Thu Mar 24, 2022 6:58 pm
Forum: Technical questions
Topic: Oric Atmos not booting - vertical lines
Replies: 15
Views: 5045

Re: Oric Atmos not booting - vertical lines

:lol: :lol: :lol:

You are a legend - that was the exact problem. All working now. :D
by john
Thu Mar 24, 2022 4:29 pm
Forum: Technical questions
Topic: Oric Atmos not booting - vertical lines
Replies: 15
Views: 5045

Re: Oric Atmos not booting - vertical lines

Thanks for all the assistance you guys. It's alive!!!! But now more issues :( Slicebit - you were spot on with the '257s Both faulty - each one had a gate inputs shorted to ground. So now it boots up and screen looks 100%. I thought finally...it's fixed...... I connect the keyboard back and pretty m...
by john
Fri Mar 11, 2022 11:37 pm
Forum: Technical questions
Topic: Oric Atmos not booting - vertical lines
Replies: 15
Views: 5045

Re: Oric Atmos not booting - vertical lines

I've now hooked it up to a RGBtoHDMI board. Thought it might be an issue with the RF side but seeing the same thing. (So I guess that at least rules out the RF section)

I tried flashing the diag rom to a 27C128 and don't see any difference on startup.
20220311_222620.jpg
by john
Fri Mar 11, 2022 8:05 pm
Forum: Technical questions
Topic: Oric Atmos not booting - vertical lines
Replies: 15
Views: 5045

Re: Oric Atmos not booting - vertical lines

Some progress - removed all the RAM and tested. Found 2 faulty and replaced but still the same screen issue. However if I remove all the RAM I get clear vertical bars with no screen 'noise' 20220311_185242.jpg Adding the RAM back and the screen goes back as shown in the first pic. One other test I t...
by john
Fri Mar 11, 2022 3:57 pm
Forum: Technical questions
Topic: Oric Atmos not booting - vertical lines
Replies: 15
Views: 5045

Re: Oric Atmos not booting - vertical lines

The plot thickens. Removed the 6502 and replaced with a known good. No difference. When I notice that D7 on the 6502 was shorted to ground. Turns out a fault with IC12 RAM. Replaced...still no difference. Noooo :evil: Think I'm going to replace/test all the RAM. Failing that will order a spare ULA.
by john
Fri Mar 11, 2022 12:25 pm
Forum: Technical questions
Topic: Oric Atmos not booting - vertical lines
Replies: 15
Views: 5045

Re: Oric Atmos not booting - vertical lines

I've tried the reset trick by pull reset to ground after power on and it fixes the white noise issue. No sound at all after a reset so clearly some reset issue in power up. However this has still not fixed the issue, though the screen does look a little different now but still with vertical lines. 2...
by john
Fri Mar 11, 2022 11:51 am
Forum: Technical questions
Topic: Oric Atmos not booting - vertical lines
Replies: 15
Views: 5045

Re: Oric Atmos not booting - vertical lines

Is there anyway to confirm if its the ULA other than to replace it? I've run through some troubleshooting guides and checked: - 5V is stable - Reset is good - Checked various clock pins - all good. - Installed test rom and not seeing any difference to the screen. Looks the same ever with the rom rem...
by john
Thu Mar 10, 2022 10:56 pm
Forum: Technical questions
Topic: Oric Atmos not booting - vertical lines
Replies: 15
Views: 5045

Oric Atmos not booting - vertical lines

I've got a oric atmos that's been sitting for years. Trying to troubleshoot why its not booting (New to oric's) Found a 7905 that was giving a 4.2V which I've replaced and its now a stable 5V. Also found a badly soldered resistor between the clock and ULA. So now its at least doing something. Was gi...
by john
Mon Oct 05, 2020 9:38 am
Forum: Hardware hacks and extensions
Topic: DRAMARDUINO - Dram tester with Arduino
Replies: 52
Views: 73769

Re: DRAMARDUINO - Dram tester with Arduino

Resurrecting a old thread here but looks like there is a critical bug in this code which causes only memory location 0x0000 to be tested. void setBus(unsigned int a) { int i; for (i = 0; i < BUS_SIZE; i++) { digitalWrite(a_bus[i], a % 1); a /= 2; } } a%1 will always result in 0 so no matter what val...