600D Colour RAM. Help!!!! SOLVED!

waltermixxx
Posts: 118
Joined: Sun Feb 03, 2019 10:31 pm

Re: 600D Colour RAM. Help!!!!

Post by waltermixxx » Thu May 09, 2019 1:57 pm

MK14HAK wrote:
Thu May 09, 2019 9:44 am
No problem here folks. Original RevD always reads $D400-D7FF top nibble as $D. Low nibble is whatever you poke it. RUN multiple times same result. (Z=0 on completion) Only no colour :mrgreen:

Address decoding ??? I wonder if the memory test program might give a clue?
Your result's are based on the Original OSI 600 REV. D, not the remake, did I read that correctly?
if so then we need some folks who built the REV. D remake to compare notes. :)

Thank you for running the test.
Turning into quite an OSI Junkie (HTFDTH?) Superboard II REV B-40K, 9600b, HC-05 Bluetooth, Superboard II Rev D, C4P rebuild- 502, 542c, 540B. :)

froso
Posts: 11
Joined: Wed Oct 11, 2017 7:01 am

Re: 600D Colour RAM. Help!!!!

Post by froso » Thu May 09, 2019 1:59 pm

Hi again, I saw the video and, the two suspects are the 8T28 and the 2114. change one of them and repeat the test, and then the other. It can be a break trace or a bad soldered, but I doubt it.

waltermixxx
Posts: 118
Joined: Sun Feb 03, 2019 10:31 pm

Re: 600D Colour RAM. Help!!!!

Post by waltermixxx » Thu May 09, 2019 2:13 pm

I was thinking also swapping out or changing U20 (74LS138) and U79 (74LS86), if there is a significant propagation delay on U79 the write pulse may not be there in time? I will see if I have another 7486 or LS86, currently using a 74LS86. I will swap around my 8T28's as well as it couldnt hurt.
Turning into quite an OSI Junkie (HTFDTH?) Superboard II REV B-40K, 9600b, HC-05 Bluetooth, Superboard II Rev D, C4P rebuild- 502, 542c, 540B. :)

Steve Gray
Posts: 283
Joined: Mon Oct 06, 2008 1:54 pm
Location: Markham, Ontario, Canada
Contact:

Re: 600D Colour RAM. Help!!!!

Post by Steve Gray » Thu May 09, 2019 2:56 pm

MK14HAK wrote:
Thu May 09, 2019 9:44 am
No problem here folks. Original RevD always reads $D400-D7FF top nibble as $D. Low nibble is whatever you poke it. RUN multiple times same result. (Z=0 on completion) Only no colour :mrgreen:

Address decoding ??? I wonder if the memory test program might give a clue?
Thanks for testing! It's good to hear that the original RevD works. Anyone with a clone want to try?

I guess Walter and I have to figure out if there is a bad chip, bad socket, or bad solder joints...

I'm still going to complete the colour circuit and make a board, so hold tight! ;-)

Steve
C4P working, C1P working. 600D Replica working, C4P+D&N floppy not working. 505 board, 610 board, Mittendorf board, TOSIE hacker board need testing, PicoDOS disk untested.

Klyball
Posts: 195
Joined: Tue Dec 09, 2014 12:53 am

Re: 600D Colour RAM. Help!!!!

Post by Klyball » Thu May 09, 2019 11:47 pm

I have had problems mixing up 8t26 and 8t28
Replica 600 Rev D:8K,CEGMON
Replica 610 Rev B: 24k,MPI B-51 with Custom Data separator D-13
510 on the bench/replica 582 backplane/replica 470a /replica 555/original 570B/2 x Shugart 851
Ongoing : 630 ,620 ,510,542c,custom 590,SA1200,592,594,596,598

MK14HAK
Posts: 350
Joined: Wed Mar 16, 2011 1:49 am
Location: New Zealand

Re: 600D Colour RAM. Help!!!!

Post by MK14HAK » Fri May 10, 2019 2:32 am

Hold the phone... This is weird, today I am getting the same problem. Hi nibble is constant $D but lo nibble is now random. I thort it may be the BASIC program and tried a few variations but now still have errors.
Using the Cegmon monitor and tabulating memory repeatedly: TD7A0,D7FF shows random read errors!
Starts to look like a timing issue? Steve are seeing colour changes at random after you have filled all memory with the one colour?
600RevB:16K,2MHz,64x32,470,CEGMON
SuperKit:502,540B,542B,CEGMON, 8" and 5" FDDs
Cards:PE IO,6522 D-A-D, AY3-8910,ProgramGraphics,Color,UK101
WIP:HexDOS,FDD Emulator

waltermixxx
Posts: 118
Joined: Sun Feb 03, 2019 10:31 pm

Re: 600D Colour RAM. Help!!!!

Post by waltermixxx » Fri May 10, 2019 3:44 am

Klyball wrote:
Thu May 09, 2019 11:47 pm
I have had problems mixing up 8t26 and 8t28
we are only using 8T28's on the 600 REV. D. :)
Turning into quite an OSI Junkie (HTFDTH?) Superboard II REV B-40K, 9600b, HC-05 Bluetooth, Superboard II Rev D, C4P rebuild- 502, 542c, 540B. :)

waltermixxx
Posts: 118
Joined: Sun Feb 03, 2019 10:31 pm

Re: 600D Colour RAM. Help!!!!

Post by waltermixxx » Fri May 10, 2019 3:47 am

MK14HAK wrote:
Fri May 10, 2019 2:32 am
Hold the phone... This is weird, today I am getting the same problem. Hi nibble is constant $D but lo nibble is now random. I thort it may be the BASIC program and tried a few variations but now still have errors.
Using the Cegmon monitor and tabulating memory repeatedly: TD7A0,D7FF shows random read errors!
Starts to look like a timing issue? Steve are seeing colour changes at random after you have filled all memory with the one colour?
once written (as far as I remember), they dont change, for instance, if Steve is writing 15 to all the memory locations then instead of the colour associated with 15 being set, it will be some random colour (like the random number the program generates). Once written it does not randomly change. it's the value when written that gets messed up. :) Steve can confirm, but pretty darn sure that is the case. :)
Turning into quite an OSI Junkie (HTFDTH?) Superboard II REV B-40K, 9600b, HC-05 Bluetooth, Superboard II Rev D, C4P rebuild- 502, 542c, 540B. :)

MK14HAK
Posts: 350
Joined: Wed Mar 16, 2011 1:49 am
Location: New Zealand

Re: 600D Colour RAM. Help!!!!

Post by MK14HAK » Fri May 10, 2019 9:13 am

Agreed U79 LS86 looks a possibility here. I only had one other amongst my spares and swapped it but no improvement. Its involved with a few timing signals and I note it is one of the few socketed TTLs on my original RevD.Could have been a select on test component. I wonder if a few pFs cap might help ? ( I also tried 550ns RAM and 4 different manufacturers 8T28s )

10 C=208
20 FOR X=54272TO55295
30 POKEX,C
40 NEXT
50 FOR X=54272TO55295
60 B=PEEK(X)
70 IF B<>C THEN Z=Z+1:PRINTC;"PEEK ";X;"=";B
80 NEXT
90 PRINTZ;"ERRORS";:PRINT" C=";:PRINTC
95L=C
100Z=0:INPUT" C";C
110IFC=0THEN STOP
115IFC=1THEN C=L:GOTO50:rem read test
120GOTO20

Entering values 223 and 208 at input prompt.($D0,$DF) Entering 1 loops on a read test. I get what appears to be both write and read errors. With not so may read errors.These appear at different locations each time you loop the read test which is understandable if this is a timing issue.
600RevB:16K,2MHz,64x32,470,CEGMON
SuperKit:502,540B,542B,CEGMON, 8" and 5" FDDs
Cards:PE IO,6522 D-A-D, AY3-8910,ProgramGraphics,Color,UK101
WIP:HexDOS,FDD Emulator

Steve Gray
Posts: 283
Joined: Mon Oct 06, 2008 1:54 pm
Location: Markham, Ontario, Canada
Contact:

Re: 600D Colour RAM. Help!!!!

Post by Steve Gray » Fri May 10, 2019 12:15 pm

waltermixxx wrote:
Fri May 10, 2019 3:47 am
MK14HAK wrote:
Fri May 10, 2019 2:32 am
Hold the phone... This is weird, today I am getting the same problem. Hi nibble is constant $D but lo nibble is now random. I thort it may be the BASIC program and tried a few variations but now still have errors.
Using the Cegmon monitor and tabulating memory repeatedly: TD7A0,D7FF shows random read errors!
Starts to look like a timing issue? Steve are seeing colour changes at random after you have filled all memory with the one colour?
once written (as far as I remember), they dont change, for instance, if Steve is writing 15 to all the memory locations then instead of the colour associated with 15 being set, it will be some random colour (like the random number the program generates). Once written it does not randomly change. it's the value when written that gets messed up. :) Steve can confirm, but pretty darn sure that is the case. :)
Correct. Some bytes are written with the wrong value and to the wrong location, but they do not change when no longer writing to colour memory.

Steve
C4P working, C1P working. 600D Replica working, C4P+D&N floppy not working. 505 board, 610 board, Mittendorf board, TOSIE hacker board need testing, PicoDOS disk untested.

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