Apple II+ Bad Memory/ROM?

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Hello all. I am a newcomer to the board. I recently purchased an Apple II Plus from eBay. Aside from a 16K expansion card, it is a bare system. No monitor, no disk drive or controller, no other expansion cards. Just the computer itself (I've separately purchased a disk drive and controller, still waiting for them to arrive). However, I know that the computer will still boot into the BASIC prompt even if no disk drive is attached, so I decided to play around with it anyway.

However, while doing so, I noticed some odd glitches that I'm fairly sure shouldn't be happening. Keep in mind that 95% of what I know about the Apple II Plus is based off 20 year old childhood memories, so my troubleshooting expertise when it comes to this old system is fairly nonexistent. However, I did try a few different things that I was readily able to recall from memory, and came up with the following symptoms:

1. Attempting to use the LIST command almost always kicks it into the program monitor at address E851, but sometimes instead it returns a divide by zero error, then freezes. The only exception to this problem is if no program code exists in memory, in which case LIST just displays a blank line and returns to the BASIC prompt, as it is supposed to do.

2. Attempting to assign a variable (For example, setting X to equal 10) kicks it into the program monitor at address E916.

3. Attempting to run the following invalid one-line program:
10 GOTO 20
Returns "UNDEF'D STATEMENT ERROR IN" with no line number given for the error, then immediately after kicks it into the program monitor at address E851

4. Attempting any math function (1+1, 9*64, 3/0, etc.) kicks it into the program monitor at address E916.

On a whim, I did a CALL-151 to enter the program monitor, dropped it down to address 0000, then did a sort of "poor man's" memory read test by holding Rept+Return, letting it read and scroll all the way through to FFFF. Whenever it would glitch, I manually went back through and stepped it one address at a time until locating the exact address that caused the glitch. These are the results I got, the addresses that caused problems and what they did:

C050 Random patterns/text/colors on screen
C080 Hard freeze
C083 Hard freeze
C084 Hard freeze
C087 Hard freeze
C088 Hard freeze

The glitch caused at C050 could be cleared by doing Ctrl+Reset. The rest were hard freezes that required the power to be turned off and back on.

Admittedly, these may be normal, and my lack of in-depth knowledge of the Apple II may make me think it's a problem. However, there is undeniably something wrong with this computer, and this is all I was able to come up with using my limited knowledge. Until I receive the disk drive and controller card, the diagnostics and tests I am able to run are quite limited.

As previously mentioned, the computer did come with a 16K expansion card. However, the problems persist even with the card removed.

So, I felt it necessary to turn to the experts here for assistance. Childhood memories that consist almost entirely of just using the system to play games really isn't enough for me to solve this problem on my own. I appreciate any assistance.

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Dog Cow's picture
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Re: Apple II+ Bad Memory/ROM?

Quote:

C050 Random patterns/text/colors on screen
C080 Hard freeze
C083 Hard freeze
C084 Hard freeze
C087 Hard freeze
C088 Hard freeze

The glitch caused at C050 could be cleared by doing Ctrl+Reset. The rest were hard freezes that required the power to be turned off and back on.

This is expected behavior. The $C0 page is all I/O locations, not RAM, so you're accessing soft-switches and things.

Here's a little memory map for you:
$0000 - $00ff : zero page
$0100 - $01ff : stack
$0200 - $02ff : input buffer
$0300 - $03ff : free RAM, but DOS usually uses the high end
$0400 - $07ff : text page 1 (or graphics)
$0800 - $0bff : text page 2 (or graphics)
$0c00 - $1fff : free RAM
$2000 - $3fff : hi-res gfx page 1
$4000 - $5fff : hi-res gfx page 2
$6000 - $bfff : free RAM
$c000 - $cfff : I/O
$d000 - $ffff : ROM

So in other words, anything above $c000 is not RAM, unless you're using the Language Card, and you have the ROM address space switched out.

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Re: Apple II+ Bad Memory/ROM?

I relayed your message to comp.sys.apple2, and I received the following response from Michael J. Mahon:

You're right--something is amiss.

High on the hit parade is memory. You might also try reseating all the
chips to clear oxide from contacts.

The 16K card provides spare DRAMs to substitute on the main board, which
can help in troubleshooting. A RAM test would be a good start, but if
page zero is bad, it probably won't run--and unless you have a cassette
version, a lot of the machine needs to work for DOS to run.

I'm sure that you replaced the DRAM chip when you removed the 16K card's
"flying lead"...

Also reseat the ROM chips and verify that they are in the correct
sockets.

You can remove the upper two banks of DRAM, creating a 16KB system
which should pass all your tests. DRAM chips can be swapped in the
low bank, and if symptoms don't change, that DRAM is probably eliminated
as a source of the problem.

Good luck in isolating the problem.

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Re: Apple II+ Bad Memory/ROM?

Well, I tried swapping the RAM chips one at a time with a chip from the 16K expansion, no luck. I also removed and reseated the ROM chips, again with no luck. As for whether they're in the correct sockets or not, I'll need to research that, I'm not familiar with that info right off the top of my head.

I now have a disk drive and controller card I can use with the system, so that should at least provide me a means of doing a more thorough diagnosis...provided I can locate or create a diagnostic disk, that is. As it is right now, the only disk I have is a DOS 3.3 System Master, and it won't even boot from it. It gets as far as showing the DOS 3.3 title screen, then immediately either crashes into the program monitor at address BBB8, or displays a bunch of random error messages, and freezes. For example, here is exactly what it's showing on the screen right now:

DOS VERSION 3.3 08/25/80
APPLE II PLUS OR ROMCARD SYSTEM MASTER

?SYNTAX ERROR IN
?DIVISION BY ZERO ERROR IN 000tu0tvs
?DIVISION BY ZERO ERROR IN

Then hard freeze. Yes, it's showing lower-case letters, which I didn't think was possible on the II Plus. So, something is definitely screwy here.

FYI, I currently have the 16K card removed, but the same thing still happens even with it installed. The white socket where the expansion card plugs in has been filled with a chip from it, so all 24 sockets on the board are filled.

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Re: Apple II+ Bad Memory/ROM?

If it behaves ok executing monitor instructions as it seems , might be AppleSoft roms?. Does it modify memory locations uniquely ? - addressing problem ?

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Re: Apple II+ Bad Memory/ROM?

(Updated after some more tinkering, see bottom)

Apologies for letting this thread lie idle for so long, got busy with the holidays and stuff.

Anyway, I've done a little bit more troubleshooting. I removed all except for the lowest 16K of memory and repeated my tests (Except for the stuff in the monitor, I understand now that was normal behavior for reading the C050 range). The problems persisted.

I then swapped out the remaining bank with one of the removed banks, so the system still had 16K but with different memory chips. Still, the problems persisted.

With the full 48K installed, I'm able to intermittently get the DOS 3.3 disk to somewhat boot. Most of the time it crashes into the monitor, but every now and then it will instead crash to the Applesoft prompt. From this point, all disk-related commands mostly work (LOAD, SAVE, CATALOG, etc. They execute, but sometimes crash to the monitor after completing), but attempting to RUN or LIST any programs loaded from the disk causes random error messages similar to my earlier testing. Until I am able to make or acquire a proper diagnostic disk, the only disk I have for testing is the DOS 3.3 System Master

Again, the problems persist regardless of whether the language card is installed or not. Same with the Disk II controller, inserted or removed doesn't affect the problem.

Admittedly, my extremely limited knowledge of the Apple II line is still limiting my troubleshooting skills, so I can't think of anything else software-wise to attempt. I'm thinking my next step should be to try replacing the ROMs. The question is...which ones should I replace? Or, should I just replace them all? I've seen full Applesoft ROM sets periodically pop up on eBay for around $60, but there's always uncertainty with how well used pulls work, and for all I know I could end up with a set in worse condition than the ones I have now.

I did find a place that sells them burned on new EPROMs with pin adapters (ReactiveMicro.com), but at $15 each, it would be pretty pricey to replace them all (I don't have the equipment or knowledge to burn my own EPROMs). However, this would give me an opportunity to purchase and replace only the specific ROM chips that are faulty, which could help limit the necessary expense to repair the system. But again, the question remains of figuring out specifically which chips are bad (I don't have access to another Apple II Plus to try swapping parts with).

Any other thoughts?

====================

UPDATE: It appears these problems are limited only to non-binary programs. I was able to successfully BRUN the "MASTER CREATE" and "FID" programs on the DOS 3.3 disk with no errors.

====================

UPDATE 2: The more I play with it, the more I learn. Since the DOS 3.3 disk crashes during boot, it never manages to make it to the point where it loads Integer BASIC onto the language card. However, I found out how to manually do this myself. Once it is loaded, Integer BASIC programs run perfectly fine with no errors.

It's almost certain to me now that one or more of the Applesoft ROMs are FUBAR'd. The question still remains though...which ones should I replace, if not all of them?

====================

UPDATE 3: I've done a little more reviewing of my troubleshooting notes, and a little more research online. A majority of the time it crashes into the monitor, it lands at an address in the E8XX-E9XX range. So, on a hunch, I am going to try replacing the E8 ROM (Ordering it from Reactive).

In the meantime, while I wait for the replacement to arrive, any other thoughts on stuff I should check or try to see if any of the other ROM chips need replacing? Apologies if I'm asking questions that should be common knowledge on here, as I've said many times over, a majority of my Apple II knowledge is based off of 20+ year old childhood memories that involved mainly using it to play games 95% of the time. I greatly appreciate your patience and assistance with this though.

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Make a RAM test first !

Hello,

First, I suggest you try this simple 48K RAM test (thanks to Jim Sather and his precious book "Understanding the Apple II") :
1. Go to the monitor (CALL -151)
2. Type in the following code (don't forget the space between 34:14 and Return).

C050 C053 C054 C057 N 265:FF N 266<265.BFFEM 266<265.BFFEV 265:0 N 266<265.BFFEM 266<265.BFFEV 34:14 (Return)

The Apple II 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.

Just tell me what does this produce.

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Posts: 48
Re: Make a RAM test first !

When executing the code you provided, the screen slowly alternates back and forth between the following two screens about once every five seconds. Apologies for the bad image quality, these pictures were taken with my cell phone:


Solid white in the upper portion, with four rows of white squares below. No other characters/text/etc. is displayed on this screen.


Solid black in the upper portion, with four rows of inverse @ characters below. No other text is displayed on this screen.

I am assuming this means the test has passed, correct?

BTW, thank you for this code! It may come in handy in the future.

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Re: Make a RAM test first !

It quits back to the monitor asterisk prompt after one pass of white+squares, one pass of black+inverse '@' signs, right? It shouldn't continuously cycle.

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Posts: 48
Re: Make a RAM test first !

No, it doesn't quit back to the monitor, it just keeps going until I do Ctrl+Reset to restart the computer. It never displays any memory addresses or other text while doing this though. No question marks appear whatsoever during the test. I also tried it again with the language card removed, same results.

For what it's worth, it does the same thing when I try this on my Apple IIc, continuously cycles back and forth between those two screens until I do Ctrl+Reset. I know for a fact that there's nothing wrong with RAM or ROM on the IIc, but also admit that the test could be "failing" on the IIc because it has more than the 48K the test was designed for.

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Re: Make a RAM test first !

I only tried it on emulators, but both KEGS and AppleWin only go through one cycle each then end.

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Re: Make a RAM test first !

david__schmidt wrote:

I only tried it on emulators, but both KEGS and AppleWin only go through one cycle each then end.

David, you forget the space after 34:14. This test only ends when RESET is pressed. It's an infinite loop.

Well, now we now for sure that the RAM chips are good.
To test the ROM chips, you can transfer the II+ diagnostic disk by using ADT.
Then, boot the disk and choose the Motherboard ROM TEST option.

See ya.

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Apple II forever

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Re: Make a RAM test first !

amauget wrote:

David, you forget the space after 34:14. This test only ends when RESET is pressed. It's an infinite loop.

Yep, you're right. I wasn't sure what you meant by that when you first wrote it, or why it would be significant.

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Re: Apple II+ Bad Memory/ROM?

Well, another update.

I was able to create a diagnostic disk using ADTPro, and ran it on the system. As suspected, it reported that the E8 ROM is bad.

Now, here's the kicker...I ordered a replacement E8 ROM from Reactive on a hunch before I even had the disk made. So, I put it in and re-ran the test.

HOWEVER...same result. With the replacement from Reactive installed, the test is still saying the E8 ROM is bad.

Now, obviously I cannot rule out the possibility of the motherboard itself being bad...and I honestly mean no ill will towards Reactive, but it needs to be said that the replacement E8 ROM I received from them was quite scratched up and appeared to have been used. So, unfortunately I cannot rule out the possibility that the ROM I received from Reactive is also faulty.

So...anyone know of another source of Applesoft E8s other than Reactive or eBay? Also, in the meantime while I search for another replacement ROM, is there anything else I can check on the motherboard itself that may be bad?

Thank you all for your patience while I continue trying to figure this out.

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Addressing issue ?

Hello,

You can check that your Apple doesn't have an addressing issue :
1. Go to the monitor : CALL-151
2. At the * prompt, type : E800.E8B7
It will display the starting hexadecimal values at E800. You can check them with the result of an Apple II+ emulator like AppleWin. Here is a starter.

If the values are totally different, this is almost an addressing issue.

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Apple II forever

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Re: Addressing issue ?

Using AppleWin 1.19.3 for comparison, I tried this with both E8 ROMs I have, and got the following results:

Using the E8 the system came with, most of the values are the same, but every couple of lines or so there are some minor differences. For example, line E800 shows "A4" in place of the second "A5", line E810 shows "05" instead of "04", and so on. I'd estimate it's perhaps a 90% match.

Using the E8 I got from Reactive, on the other hand, gives me nothing but a screenfull of "A0", "FF", "C1" and "C6" with a few other random values scattered around. Absolutely none of it matches up with what it shows in the emulator. On a whim, I did E800.EFFF to skim through the whole E8 ROM Reactive sent. Obviously I can't read as quickly as it was scrolling, but the initial appearance of the various values I could briefly make out, along with the last page when it stopped scrolling, suggested the entire ROM is the same way. Then, on another whim, I turned off the system, removed the E8 ROM completely, turned it back on, and did E800.EFFF again...exact same results. So, either the E8 Reactive sent me was never flashed, or it has a problem that simply makes it appear as if it's not even installed. It needs to be said that the ROM they sent didn't come with a 2316 adapter as the site claimed it would. Also, as mentioned earlier, it's quite scratched up, as if it's been inserted/removed several times before.

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Use an EPROM adapter

Hello,

You can not plug an EPROM directly in the Apple without an adaptor.
Take a look here and it should work (thanks to Understanding the Apple II by Jim Sather).

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Apple II forever

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Re: Apple II+ Bad Memory/ROM?

The saga continues with another update. This is more of an FYI for those following the progress of this, since I imagine we've exhausted just about every possible troubleshooting step software-wise.

I contacted Reactive, and they sent me the missing socket adapter they forgot to send the first time around, and it is now installed along with the EEPROM I received from them. Unfortunately, it is still failing the diagnostics, with E8 still indicated as being bad. I tried doing E800.E8B7 again, and most of the values (I'd estimate 95%) match the screenshot provided by Amauget above, but some values are still incorrect. So, even with the adapter, it appears the ROM I got from Reactive is still faulty.

I'm going to contact them again to see what my options are for replacement, but I'm thinking I've passed the deadline for returns/exchanges, since it's been a month since I ordered it (Work and other life events have prevented me from working on this project in a more timely manner unfortunately). Hopefully, eventually, I'll get this up and running again!

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No News ?

Hello torindkflt,

What are the news ?
Have you finally overcome your problem ?

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Apple II forever

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Re: No News ?

Apologies for the lack of an update. I was finally contacted earlier this week by Reactive, and they are going to send a replacement ROM. I should receive it in a few days. Hopefully this will solve my problems.

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Re: Use an EPROM adapter

That solution is not compatible with language cards. See my page on Apple II prom solutions.

http://www.willegal.net/appleii/appleii-integer.htm

Regards,
Mike Willegal

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Re: Use an EPROM adapter

Mike WIllegal wrote:

That solution is not compatible with language cards.

Absolutely ! Here are a text and schema for a language card compatible adaptor.

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Antony
Apple II forever

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Re: Apple II+ Bad Memory/ROM?

Apologies for any confusion. I am not attempting to plug the replacement ROM into the language card. It is being inserted in the E8 socket located on the motherboard. At the moment, I do not even have the language card inserted for troubleshooting purposes.

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Re: Apple II+ Bad Memory/ROM?

Hi torindkflt,
There is no confusion at all : Mike simply points out that if you use a bad adaptor to plug the EPROM on the motherboard, there will a conflict WHEN you will add the Language Card.
By the way, the Language Card already got pads in order to use an EPROM directly.

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Re: Apple II+ Bad Memory/ROM?

So I am troubleshooting yet another Apple II+ but this one has Integer ROMs on the motherboard.

Boots to monitor prompt, and I can get into Integer Basic.

I have it finally able to boot the Apple Confidence disk, which reports only 32 K of RAM present although all 3 banks are populated.

When it runs, it always reports that the first chip in bank 2 is bad. I have replaced/swapped and re-swapped this chip out to no avail. And I've tried 3 different sets of chips in bank 3 and it won't recognize it.

This is a Rev 4 board with the soldered jumpers - wondering if that might be causing me heartache?

Anybody have any thoughts?

Jen

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Re: Apple II+ Bad Memory/ROM?

Hi Jen,

AFAIK, the confidence test doesn't tell you which RAM chip is bad. A single 1 is just printed.
If only 32 Ko are shown, it's perhaps a bad IC in row E.
If you are sure all the RAM chips are good (try them into another machine or swap an entire row in this one), you can try to change the LS139 located at F2.

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Apple II forever

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Re: Apple II+ Bad Memory/ROM?

Hello Jen,

it sounds to me rather more that not the RAM-chips are faulty but
instead the adressing of the RAM banks cause the problem.

The lucky thing is that this is performed by rather cheap LS-Logic chips so a possible
repair would not become that expensive and that chips may be order by a large electronic
supplier like
Jameco
easily within days.
The chips related to adressing of the banks are in the hitlist by chance of being faulty:
2 x 74LS139 at location F2 and at location E2
1 x 74LS153 at location C1
2 x 74LS257 at location J1 and at location C12
1 x 74LS04 at location C11
1 x 74LS20 at location D20
1 x 74LS08 at location H1
or 1 x 74LS32 at location C14

The entire bunch of 9 chips should cost less than 10 U.S. Dollars
and shipping should be the most expensive in the bill.

Checkout that list of chips at the spotted locations if any of that
"suspects" gets more suspicious than it´s companions in the list
- by oxydation at the pins
- bent legs underneath the chip and not inside of the socket
- damaged socket or
- damaged trace to the socket at the solderside.

by that you might even shorten the list ....
otherwise you may swap all in a bunch check out working condition
and then step by step swap back original chips to verify the really faulty chip.

sincerely speedyG

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Re: Apple II+ Bad Memory/ROM?

Well I ran that cool memory check routine in Monitor that is in this thread... According to that here are the first addresses that are bad: (there are so many it scrolls off the screen)

445E-FF (DF)
445F-DF (FF)
4559-FF (DF)
455B-DF (FF)
etc

I will try the chip replacement, as I have a few "donor" motherboards that have all of these chips intact still.

Hopefully its one or more of them!

Thanks guys, for giving me hope!

Jen

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Re: Apple II+ Bad Memory/ROM?

Ran across some code I wrote years back that loads Integer Basic along with The Inspector/Dr Watson to the language card of the Apple II.
The code loads at $6000, you execute it at $6000 and it takes care of the rest.
Once executed, you can type "INT" for Integer Basic or "FP" for Applesoft. Call-151, D000G for Inspector and D800G for Dr Watson.
If you're interested:
https://www.dropbox.com/s/yhhljiy4035hc0y/IntBasicInspectorDrWatsonExecutable%246000.BIN?dl=0

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Re: Apple II+ Bad Memory/ROM?

Am working on yet another orphaned Apple II+ and when I run the memory test it flags a single address as questionable:

7FFF-FF

Can anyone here help me identify what this is telling me? (Like which chip or bank it might be?)

Many thanks!

Jennifer

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Re: Apple II+ Bad Memory/ROM?

Hi Jennifer,

It should be the second bank, row D.
You can try to swap row D and row E and see if the error moves to the $8000-$BFFF range.

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Apple II forever

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Re: Apple II+ Bad Memory/ROM?

Done!

Turns out 3 of the RAM chips were bad!!

Thank you for the assistance!!

ps: I ran them through a 4116 ram tester that you can order as a kit:

http://neoloch.com/products/Inquisitor.php

You buy the main board/kit and then the additional 4116 tester and build them - fun (and easy) to build and it works great!!

Jennifer

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Re: Apple II+ Bad Memory/ROM?

I came across this thread, and having trouble with RAM chips myself, I tried the 48K RAM test:

C050 C053 C054 C057 N 265:FF N 266<265.BFFEM 266<265.BFFEV 265:0 N 266<265.BFFEM 266<265.BFFEV 34:14 (Return)

What I got back is in this video:

https://www.dropbox.com/s/548dj190596paz0/48K_RAM_test.mov?dl=0

Are those numbers on the bottom bad RAM chips?

Edit:
Maybe I'm crazy, but man, I like those things on the screen. Smile :) Smile

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