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Icky - Progress
Posted: Tue Sep 18, 2018 3:07 pm
by Icky
- IMG_3057.png (445.75 KiB) Viewed 7864 times
Here is the current status of my board so we can track progress of where each of us are:
- Board built without blitter and using Exxos Ram Board with a 4MB SIMM installed.
- Modifications installed so far https://www.exxosforum.co.uk/forum/viewtopic.php?f=19:
- Jumper Pads - SJ1 - 5 all linked (soldered)
- Reset Fix - R920 leg moved to be soldered to diode, tracks cut and patch wire in place
- Hsync Fix - Pin 8 leg removed from U51 socket and Pin 8 and 9 on underside of board soldered together
- Using the scope on the GLUE the board is producing 15.6kHz and 50Hz out. For the 50Hz it is initially 60Hz then immediately goes to 50Hz
- On every switch on or reset I get a full white screen that turns to black screen with white border. Sometimes it stays solid but more than often it starts scrolling horizontally.
This evening I am hoping to do a lot of scoping to see what else is going on
Re: Icky - Progress
Posted: Tue Sep 18, 2018 3:21 pm
by exxos
I would first double check continuity on the ROM socket first of all.. socket problems are pretty common
Sounds like your getting some TOS init at least, it must be setting the palette to get a full white screen.. but never seen it go black after that..
Also please check BERR on the CPU...
Re: Icky - Progress
Posted: Tue Sep 18, 2018 5:22 pm
by Icky
exxos wrote: ↑Tue Sep 18, 2018 3:21 pm
I would first double check continuity on the ROM socket first of all.. socket problems are pretty common
Sounds like your getting some TOS init at least, it must be setting the palette to get a full white screen.. but never seen it go black after that..
Also please check BERR on the CPU...
Checked continuity and socket is ok.
BERR on CPU goes high 5v at start and stays there
Re: Icky - Progress
Posted: Tue Sep 18, 2018 5:33 pm
by exxos
Icky wrote: ↑Tue Sep 18, 2018 5:22 pm
BERR on CPU goes high 5v at start and stays there
What about BG, BGACK, BR ? All those should stay high all the time...
Re: Icky - Progress
Posted: Tue Sep 18, 2018 6:00 pm
by Icky
exxos wrote: ↑Tue Sep 18, 2018 5:33 pm
What about BG, BGACK, BR ? All those should stay high all the time...
BG and BGACK are high all the time but BR is low all the time
Re: Icky - Progress
Posted: Tue Sep 18, 2018 6:02 pm
by exxos
Icky wrote: ↑Tue Sep 18, 2018 6:00 pm
BG and BGACK are high all the time but BR is low all the time
hmmm, AFAIK nothing should be requesting the bus during startup (other than DMA stuff, blitter, ) Even so, CPU isn't granting the bus to anything either.. so that is odd...
Re: Icky - Progress
Posted: Tue Sep 18, 2018 6:05 pm
by exxos
hmmm.. I can't see a pull up on BR anywhere... so checking to see whats happened there...
Re: Icky - Progress
Posted: Tue Sep 18, 2018 6:12 pm
by exxos
OK.. "bodge wire 1" time...
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Re: Icky - Progress
Posted: Tue Sep 18, 2018 6:13 pm
by Icky
exxos wrote: ↑Tue Sep 18, 2018 6:12 pm
OK.. "bodge wire 1" time...
OK - Lets give it a go
Re: Icky - Progress
Posted: Tue Sep 18, 2018 6:18 pm
by exxos
Icky wrote: ↑Tue Sep 18, 2018 6:13 pm
OK - Lets give it a go
Looks like BGACK hasn't a pull up either
out of room on the RP's, so bodge resistor time...