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Ibm pc 5150a..... Possibly a pre-release build???

I have not followed every post in this thread, but are you saying that you can't ID the bad RAM? That should not be very difficult. If you set the jumpers to minimum RAM setting and test one page / block at a time you'll gather a good set of RAM. Max the system out with the good RAM you have, even if that's only 16K. At least you can boot into BASIC then. BASIC uses separate RAM from the free/open RAM.
BIll
 
billdeg said:
I have not followed every post in this thread, but are you saying that you can't ID the bad RAM? That should not be very difficult. If you set the jumpers to minimum RAM setting and test one page / block at a time you'll gather a good set of RAM. Max the system out with the good RAM you have, even if that's only 16K. At least you can boot into BASIC then. BASIC uses separate RAM from the free/open RAM.
BIll
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Thanks Bill... I am not sure if there is bad RAM. It will not power up to the beeps using the minimum diagnostic configuration found here: http://www.minuszerodegrees.net/5150_5160/MDC/minimum_diag_config.htm

In my other 5150, it was bad RAM chip identified by piggy backing each chip in bank 0 until I found a bad chip at U42. On this one, I cannot find a bad RAM chip in bank 0 using the piggy back technique. i have piggy backed them all in Bank 0 simultaneously with many different chips with no luck. I have confirmed a good power supply and U33 BIOS chip. Power supply voltages are perfect with motherboard plugged in so it is not a shorted cap. If there is anything else I can look for before putting $50 or so in a diagnostic ROM, I would appreciate any help that you can provide.
 
This is still related to the 1981 5150:

If I have an Olivetti M24 with a 2764 chip, can I use that to make a diagnostic ROM? It would save me from buying the adapter and eprom (about $18 ).... unless of course the programmer would not accept this chip.

I have 2 of these old M24s (actually Xerox 6060's made in Italy). Lots of usable chips. If they have any value, perhaps I should not cannibalize them??

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PCFreek said:
Thanks Bill... I am not sure if there is bad RAM. It will not power up to the beeps using the minimum diagnostic configuration found here: http://www.minuszerodegrees.net/5150_5160/MDC/minimum_diag_config.htm

In my other 5150, it was bad RAM chip identified by piggy backing each chip in bank 0 until I found a bad chip at U42. On this one, I cannot find a bad RAM chip in bank 0 using the piggy back technique. i have piggy backed them all in Bank 0 simultaneously with many different chips with no luck. I have confirmed a good power supply and U33 BIOS chip. Power supply voltages are perfect with motherboard plugged in so it is not a shorted cap. If there is anything else I can look for before putting $50 or so in a diagnostic ROM, I would appreciate any help that you can provide.
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You should be looking at the switch settings for the older 16-64K motherboard, right? THey're not the same as the later 5150/60 MB, are they?
 
billdeg said:
You should be looking at the switch settings for the older 16-64K motherboard, right? THey're not the same as the later 5150/60 MB, are they?
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I have tried it with the settings as they were originally and have tried it with all switches set to off. Yes it is a 16k to 64k motherboard and is different, but I have been told that when running it with the minimum diagnostic configuration, only #5 and #6 on switch 1 matter. With both off, I still do not boot to a beep regardless of my multiple piggy backed RAM configurations as stated earlier.
 
PCFreek said:
I have tried it with the settings as they were originally and have tried it with all switches set to off. Yes it is a 16k to 64k motherboard and is different, but I have been told that when running it with the minimum diagnostic configuration, only #5 and #6 on switch 1 matter. With both off, I still do not boot to a beep regardless of my multiple piggy backed RAM configurations as stated earlier.
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Get an IBM manual that matches your motherboard, otherwise you're never going to get anywhere. You do not need a diagnostic ROM. Just the correct settings and at least one good row of RAM. Keep this simple.

What's equally important is that you have correct switches for the disk drive(s) installed, monitor type, and whether you have a co-processor installed. You need to get this right.

bd
 
billdeg said:
Get an IBM manual that matches your motherboard, otherwise you're never going to get anywhere. You do not need a diagnostic ROM. Just the correct settings and at least one good row of RAM. Keep this simple.

What's equally important is that you have correct switches for the disk drive(s) installed, monitor type, and whether you have a co-processor installed. You need to get this right.

bd
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It will not boot in the minimum diagnostic configuration meaning there is just the power supply and speaker connected to the motherboard (and no co-processor). As I understand it, switches (other than #5 and #6 on SW1) do not matter. I would love to get this going without buying the parts to make a diagnostic ROM. As stated earlier, I have a good later model 5150 and have confirmed that my BIOS and my power supply are good by powering up the later motherboad with the older power supply, speaker, and BIOS chip installed.

So I believe that I can take switches out of the equation and I know I have a good power supply and BIOS, but the machine still will not boot to a beep. Faulty RAM may or may not be the problem. I do not know for sure what the problem is. I piggybacked the RAM (every single chip) in bank 0 simultaneously and in every possible configuration with no luck. Short of a diagnostic ROM (and not worrying about switches), any suggestions on what i should do next?
 
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Believe what you want, you'll do yourself a favor if you look up the switches in the IBM manual for that specific motherboard.
 
billdeg said:
Believe what you want, you'll do yourself a favor if you look up the switches in the IBM manual for that specific motherboard.
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please do not think I am discounting you... it is just a question that I asked before and got it on good authority that the switches did not matter. I will look into the switch settings. I appreciate your help and any help I can get! Thank you very much!!
 
billdeg said:
Here's a link with additional info on switch settings on a similar box.

http://www.vintagecomputer.net/browse_thread.cfm?id=161
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Thanks... the link that you reference is different from my situation... your "initial status" already had the machine booting to 3 beeps. I get no beeps. speaker crackles for a split second and then nothing...

I did go ahead and change the switches to match my machine's current state and I still get no beeps.
SW1: 1 ON (no floppy drives)
SW1: 2 ON (no co-processor)
SW1: 3 and 4 - tried all combinations from only bank 0 populated to all banks populated
SW1: 5 and 6 - both OFF as recommended in the minimum configuration test procedure
SW1: 7 and 8 - tried them both ON and both OFF but it should not matter when switch 1 is ON

SW2: 1-5 - All ON (64k RAM)
SW2: 6,7,and 8 - all OFF
 
Of interest, check out the speaker mount. I haven't seen another one like in a 5150 online. The aluminum T shaped piece is a spacer that either serves to move the speaker an eighth inch deeper into the cabinet, or it keeps the screws from going too far past the speaker mount... or, of course, both.

P4090110.jpg

I still need some beeps and welcome any advice...
 
PCFreek said:
If I have an Olivetti M24 with a 2764 chip, can I use that to make a diagnostic ROM? It would save me from buying the adapter and eprom (about $18 ).... unless of course the programmer would not accept this chip.
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I wouldn't bother...it's likely anyone with a programmer has a pile of 2764s, they're extremely common. I have both a pile of 2764s and an EPROM programmer, so PM me if you can't find anyone local to program one for you.

As to testing/replacing 4116 RAMs, I usually use a modified 4164 RAM. They're more reliable than 4116 RAMs in my experience. I also have a huge pile of 4164s if you need them.
 
glitch said:
As to testing/replacing 4116 RAMs, I usually use a modified 4164 RAM. They're more reliable than 4116 RAMs in my experience. I also have a huge pile of 4164s if you need them.
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the 2 Olivetti's (Xerox PC 6060) that I have are full of 4164 chips... JACKPOT! my old 5150 is actually full of 9016 chips. Only four 4116 chips in it.
 
PCFreek said:
my old 5150 is actually full of 9016 chips. Only four 4116 chips in it.
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They are, for all intents and purposes, the same thing. 9016 is just AMD's number. Incidentally I just tested 64K of bad AMD 9016/4116 RAMs from a S-100 memory board. Not a single good one!
 
I just piggy backed every single chip in bank 0 with my new collection of 4164 chips... nothing :( no beeps :(
 
A comment about wrong motherboard switch settings on a good IBM 5150 motherboard:

If the two video switches are incorrectly set, you may not see video (and you may damage your monitor), but you will at the least hear the POST issue a single beep when it has completed. If switch SW1:1 is OFF, you will then see drive A: being accessed.

If the video switches are set correctly, and some (or all other) switches are not, you will at least see video.

If ALL switches are incorrectly set, you may not see video (and you may damage your monitor), but you will at the least hear the POST issue a single beep when it has completed. If switch SW1:1 is OFF, you will then see drive A: being accessed.


PCFreek has a 5150 motherboard that neither issues a beep at the end of POST, nor displays video. Therefore, cause not related to motherboard switches.
 
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