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  • Bad RAM

    From Steven Nelson@21:1/5 to All on Mon Nov 28 14:55:22 2022
    Bad RAM (one of) my //e isn't working. System test gives screen mostly of ` characters/ that is '`' or "`" or the back quote char under tilde ~. Amongst this garbage is the string `jRAM````q`q`q`q`p`p`q`q` Are the p good (0) and the q bad (1). or
    is p bad and q good? I am aware the string is reversed from the board layout and corresponds to chip locations 13 12 11 10 9 8 7 6. I pulled two other //e out of storage and they had bad ram also. Also this machine has no beep at startup but the
    speaker does click when.if i can get into monitor and sta c030 sta c030. Help?

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  • From Steven Nelson@21:1/5 to Steven Nelson on Mon Nov 28 15:21:12 2022
    On Monday, November 28, 2022 at 4:55:23 PM UTC-6, Steven Nelson wrote:
    Bad RAM (one of) my //e isn't working. System test gives screen mostly of ` characters/ that is '`' or "`" or the back quote char under tilde ~. Amongst this garbage is the string `jRAM````q`q`q`q`p`p`q`q` Are the p good (0) and the q bad (1). or is p
    bad and q good? I am aware the string is reversed from the board layout and corresponds to chip locations 13 12 11 10 9 8 7 6. I pulled two other //e out of storage and they had bad ram also. Also this machine has no beep at startup but the speaker does
    click when.if i can get into monitor and sta c030 sta c030. Help?

    I swapped RAM chips around. The screen remains the same. same lowercase p and q -s. Is it a MMU problem? Zip chip problem?

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  • From [email protected]@21:1/5 to All on Tue Nov 29 08:01:12 2022
    Have you tried reseating all the socketed chips?

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  • From Steven Nelson@21:1/5 to [email protected] on Tue Nov 29 09:58:59 2022
    On Tuesday, November 29, 2022 at 10:01:15 AM UTC-6, [email protected] wrote:
    Have you tried reseating all the socketed chips?

    Removed all interface boards before doing system test. Reseated the 8 ram chips, the emu, the you, and the zip chip (cpu). No effect. Still trying to determine if or which ram chips are bad. I ordered 16 4164 ram chips from Jameco but none of them
    are helping. I don't know if they are CAS before RAS.

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    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Steven Nelson@21:1/5 to Steven Nelson on Wed Nov 30 10:13:58 2022
    On Tuesday, November 29, 2022 at 11:59:01 AM UTC-6, Steven Nelson wrote:
    On Tuesday, November 29, 2022 at 10:01:15 AM UTC-6, [email protected] wrote:
    Have you tried reseating all the socketed chips?
    Removed all interface boards before doing system test. Reseated the 8 ram chips, the emu, the you, and the zip chip (cpu). No effect. Still trying to determine if or which ram chips are bad. I ordered 16 4164 ram chips from Jameco but none of them are
    helping. I don't know if they are CAS before RAS.

    Still confused on RAM errors. The video screen is displaying correctly now. System check shows "RAM 11000111" which to me shows errors in chip locations 6 7 8 11 12 13. But a 48k ram check shows no errors. In monitor "co50 c053 c054 c057 n 265:
    ff n 266<265.bffem 266<265.bffev 265:0 n 266<265.bffem 266<265.bffev 34:14 " (space after 34:14 then return) The AppleII will go to HGR mode and display white and dark graphic screen along with question marks and inverse @ characters at the bottom of
    the screen. If some RAM chips are bad, faulty addresses will be printed on the bottom of the screen. I get the flashing black/white screen and inverse @ but solid blob instead of ? char. This is a enhanced //e and not a ][+ so that may be the reason
    for ? char difference. Anyway, no faulty ram are indicated. In Applesoft, trying "10 ?6+3" then run gives sysntax error in line 65xxx. So definitely a problem in upper 16k. ROM or RAM?
    If system check shows bad ram why doesn't 48k ram test show bad ram? I changed all the RAM chips but the system check always shows the same RAM pattern. Swapping a 0 chip with a 1 chip doesn't change anything. I am not trusting the system check at
    this point. Next step is to hook up a disk drive and see if I can boot a diagnstic disk. Not sure a system will load though. I think I need to isolate the problem(s) first. Thnx for any help.

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  • From Steven Nelson@21:1/5 to All on Thu Dec 1 08:02:08 2022
    Relax. The machine auto-repaired itself! No more errors. Installed a ext80col card, duo disk drives booted A2e diagnostics v1.2 and all went well. Installed unidisk3.5 and booted a2osx build 2552. All is well. Next is CFFA and uthernet2. Hurrah!
    Moving on to machines 2 & 3. Similar problems but issues with keyboards etc.

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