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Showing results for 'Shoestring's RAM tester'.
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Hi all. I've been fairly busy working on a DRAM & Basic ROM tester for 64kb Atari systems. This is really my first attempt at writing any 6502 for the Atari but I wanted to start off with something simple before I started porting some c64 games to the Atari. It gives me a chance to learn more about the hardware. I've finished testing in MAME and Altirra and I am currently testing this on real hardware to catch any last minute bugs or make improvements before I release it... for free of course. This program installs in the OS ROM socket and is used as a means for testing the DRAM and Basic ROM. If you have some spare 27c128s lying around then this can easily be installed. I've currently purchased a few different systems to test my program in. But I might need some help from someone to test in an A800XLF system if I can't get my hands on one. What it does. Performs data line integrity checks ( checkerboard and inverse, walking 1s and walking 0s, 1s and 0s and exhaustive ) Exhaustive takes the longest and is probably overkill. Tests 0x0-0x7ff first to test integrity of the stack and lower mem before using it. Tests 0x800-0xbfff Copies the program rom into DRAM once the above memory verified good. Turns the OS ROM off then tests the DRAM 0xc000 - 0xFFFF. Displays bit pattern / test being performed written to DRAM ( also useful for verifying video hardware / PMG ). Plays sound to indicate CPU is functioning ( for systems playing blind ). To do. 1. Code for address line integrity ( walking 1s/0s ) checks are in but are currently not being used, this will be added in a later version of its feasible and necessary. 2. Write a version for stock 600xls or adapt the current image to handle those systems. 3. Look at writing a version for the Atari 800 for stock 48k systems. 4. Add another indicator / arrow to point out which memory region is bad. 5. Any other suggestions ? Here is a video of an example of bad ram and bad basic rom. ram test.mp4
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I have been going through my Atari collection to see what still works. This 800XLF was known to be faulty, but not known to be a 800XLF, and was sitting in my garage until recently. I was therefore not surprised when it still refused to boot at all. I tried Shoestring's ROM/RAM tester blown into a 27C128 EPROM after socketing the Atari OS ROM and at least that gave me a frozen screen proving some main chips were working, but I was still doubting it could be the DRAM as it was Samsung manufactured and not Micron Technology as is usually the case with failed DRAM. To that end I swapped Freddie, Sally and PIA before I measured the voltage at the DRAM which was lower than I would have expected at 4.81 Volts with a new Meanwell 5V 3A supply. Not having another tester to hand I tried the drop of isopropanol on each DRAM chip trick, to see which one might be faulty by observing the rate of evaporation. It was 6 of the 8 DRAM chips that turned out to be faulty! I replaced the DRAM and reworked the extra RAS pull-up resistor so that it's underneath the board now, together with the TFHH mod of an additional 100nF capacitor across the Freddie chip supply. I attach pictures:-
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Looking for help with my 65XE (boots direct to memory test)
TZJB replied to i4000's topic in Atari 8-Bit Computers
In all likelyhood it will, be a DRAM problem. I have been upgrading my collection of 65XE and 130XE recently to 320K using the 800XE320K EMMU GAL from TFHH and some XEs have had similar issues to this. In most cases it was the 4164 DRAM that had failed, mostly Micron Technology, but more recently Samsung, in an 800XLF that I found to have had a fault label I had written about 20 years ago! I have also had 2 out of 6 XEs with faulty Sally CPU's. Apart from that the other big chips have worked solidly. If you have a spare 128K EPROM and programmer, and can replace the OS chip, Shoestring's ROM & RAM tester is quite useful, except it locked up when I had 6 of the 8 DRAM chips faulty in the XLF. Diagnostically, it did prove that I could get a picture. Probably the PBI plug-in board Sys-Check V2.2 XL/XE from TFHH would prove it either way, but if the existing DRAM is MT then good practice is to change it out for a different manufacturer anyway. There is a GAL16V8 JED file for the MMU too from Mathy's web site, but it's unlikely to be the problem. So DRAM and DIL sockets are probably the way forward for now. Incidentally if you purchase 41256 DRAM, these can be substituted for the 4164 for testing purposes, or even permanently if they are a good price, and are also good for the 320K upgrade of course! From what you have said, the 65XE should have the potential of holding 16 DRAM chips. -
Another possibility to identify bad RAM chip is Shoestring's RAM tester https://atariage.com/forums/search/?q=Shoestring's RAM tester&quick=1
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Alright... so somethings up with Extended RAM, and possibly RAM under the OS if Disk based Sparta isn't working as well... (can it boot SpartaDOS 3.2?) Make a text file called CONFIG.SYS on D1: with the following line, and boot SDX with this disk mounted in D1: USE NONE This will tell SpartaDOS X not to use RAM under the OS, or a bank of extended memory. MEMLO will be too high for most things to run, but see if you can at least get through to the prompt and access partitions without errors... If that works, then move up to booting using RAM under the OS: USE OSRAM If that doesn't work, then either your MMU, EMMU, or maybe base RAM is still bad... To rule out the base RAM, without purchasing a sys-check from tf_hh, you can first try replacing the OS ROM with a 27c128 type EPROM programmed with Shoestring's RAM tester. In a stock 130XE, that most likely means desoldering & installing a socket though... Syscheck and Shoestring's testers are the only ones I know of that will tell you the specific IC location that is bad. Lastly, swapping R110/R111 will swap the extended and base 64K RAM, which allows testing the extended 64K with either tester since they only test the base 64K, as seen in this post: https://atariage.com/forums/topic/251315-sys-check-v22-ready-to-use-batch-available/?do=findComment&comment=4374699
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Finally circling back onto this project today. I grabbed Shoestring's 8bit RAM tester, tossed it on a EEPROM and fired it up. We at least have life now and it shows something on the screen! Unfortunately it fails immediately with a red arrow next to U13. I swapped U13 with a known good RAM from another 800XL, and still fails the same way. Swapped all the RAM with known good RAM from the other 800XL and same failure. Start walking through and swapping chips from the broken 800XL to the working one and I've found that the PIA also causes the other 800XL to fail startup, however putting the known good 800XL in the failing system still doesn't resolve the issue. SO I've gone brute force and have one by one been swapping the ICs from the failed system into the working system, assuming a secondary failure of two ICs maybe? All the logic chips test fine and the working system boots when them in. I'm at the point when I'm ready to start testing/replacing individual discrete components, but hoping the fact that the 6520 is toast might be a hint as to where else to look? I did notice that on my failed system there is a resistor "bodged" in at the factory to pin 2 of each DRAM chip whereas on my donor working system that resistor is not there.
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Sys-Check V2.2 ready-to-use batch available
Nezgar replied to tf_hh's topic in Atari 8-Bit Computers
Sys-check should just repeat the same tests when you press start.. What happens if you press reset at that point? (At the black screen) May also be interesting to know if any odd behaviour also shows up with @shoestring's RAM tester (replacement OS ROM - either flash into a slot on the syscheck, or swap the IC on the motherboard). https://www.jammarcade.net/shoestrings-atari-8bit-ram-tester/ -
Options for 130XE Memory Chip Replacement?
Nezgar replied to 800_Rocks's topic in Atari 8-Bit Computers
First order of business.... Swap one end of the two resistors on R110/R111 to swap the base 64K U13-and extended 64K (U26-U33). The machine may then boot up OK if the extended RAM is OK (now being used as base RAM) Otherwise if you either buy a SysCheck 2.2 (which has a memory test OS ROM as one of the selectable OS's) or socket your OS ROM and temporarily replace it with Shoestring's memory tester, you can find out which base RAM chips are specifically at fault. Although the general recommendation with "Mt" brand chips is to replace them all - they are a very common failure point in XE's. Others will likely eventually fail even if you replace some individual bad ones...
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You can't use a Sys-check on that model of 65XE. (No ECI) In lieu of that, you could try shoestring's memory tester - programmed to an EPROM to temporarily replace your OS ROM. You'd have to desolder and socket your existing OS ROM. PM me if you don't have the means to program one - I could mail you a socket and a programmed chip. https://atariage.com/forums/topic/282022-shoestrings-atari-8bit-ram-tester/ https://www.jammarcade.net/shoestrings-atari-8bit-ram-tester/
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Swap the Main and Extended 64K to allow a memory tester like Shoestring's, or Sys-check to test the extended as base RAM 64K by cris-crossing R110 /R111 like so: This can also be a quick and dirty way to get a non-functional 130XE to boot, if the base 64k is bad, and extended 64K is good.
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What are you using to conduct the RAM tests? the built in 'self test' is not very thorough, and doesn't test the extended RAM. You may still have RAM issues, or possibly bad ANTIC, MMU, or some timing issues with buffer logic... If you have another XL or XE, you can try swapping chips - but that is tedious in most XE's as it would require desoldering/socketing... Try some other main memory tests in the ATR from this post: https://atariage.com/forums/topic/189604-small-thing-memtest-10-1996-jaku-b/?tab=comments#comment-3815398 I could mail you a EPROM programmed with Shoestring's RAM tester you can temporarily put in place of the OS ROM that is very thorough - If interested PM me.
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800XL hangs at blue screen with cursor
matirwin replied to matirwin's topic in Atari 8-Bit Computers
I am glad that this post was able to help you and thanks for shoestring as well for the ram tester as it helped me narrow my issue. Also the dragonstomper under your username ... that reminds me I had that cassette when I was a kid for my 2600 and supercharger, lots of great memories. -
Could also be a dead ROM... Is he close enough to you to try attaching your Sys-check on his system? (I believe you had one?) That would supplant the internal RAM and/or OS of either of those are bad. Otherwise, in lieu of a sys-check or another system to swap IC's with, I could mail a replacement programmed EPROM. Probably the cheapest thing to replace first. I can also include a 2nd OS EPROM programmed with Shoestring's RAM tester to know for sure the RAM is good too, and if not narrow down the specific chip. PM if interested.
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That’s what I need, a proper ram tester. Guess work only gets me so far. For all I know most of the ram might be bad but at least I’ve seen it play some games so the graphics and audio seem ok. however the extra ram and mmu are an unknown so far.. the shoestring rom needs a 27c128 ... I’m not sure I can burn that but I’ll check. Does Atari have test cartridges like the c64 ?
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Sys-Check V2.2 ready-to-use batch available
bfollowell replied to tf_hh's topic in Atari 8-Bit Computers
I'm pretty sure when you press Start, it's supposed to move on to the OS checks. When I first startup, the RAM test run automatically, then it stops, tells you the results, which mine says memory OK. At that point, at the bottom of the screen it says press Start to proceed. That's when it is supposed to move on to the OS tests. It's just that that never happens with mine. I just get the black screen and nothing else happens. I'll play with it some more in a day or two, when I have the time, and double-check what happens when I press Reset, and I'll also look into flashing @shoestring's RAM tester into a slot onto my SysCheck and trying it out. Thanks. -
130XE behaves in a weird way - memory problem?
Nezgar replied to aquaz's topic in Atari 8-Bit Computers
If you'd like to minimize desoldering & cutting, I again recommend running the RAM test using a sys-check board, or shoestrings ram tester replacement OS ROM to first isolate specific chips to target... My offer to send you a chip programmed with shoestring's RAM tester still stands, total cost mailed to US would be $5. Much cheaper to start with if you dont want to jump for a sys-check right away. -
It could still very likely be the ROM... usually a red or green screen though, not grey. Anyhow - I've seen at least 4 XEGS's revived by replacing that alone in the last couple years on this forum... Unfortunately, all chips are soldered to the motherboard in XEGS's, so replacing any chips will require careful desoldering and replacing with a socket - or just cutting the pins off the original ROM to ease removal of the pins one by one. I can mail you a replacement programmed EPROM and socket - I have the parts onhand. Probably the cheapest thing to replace first. I can also include a 2nd OS EPROM programmed with Shoestring's RAM tester to know for sure your RAM is good too. PM if interested. In the mean time - Since you have a working 800XL, if you want to go through the work/risk of desoldering IC's, you could try swapping them one by one into your 800XL - starting with the CPU as you suspect. Also interchangeable are ANTIC, GTIA, PIA, POKEY - but the ROM and MMU are not. Edit: Hmm, actually an 800XL ROM probably would work in the XEGS for a quick test - you just would have no working BASIC, or Missile Command...
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Any difference in behaviour with/without keyboard attached? Does the memory test find any faults? Does it test 40 or 48 blocks? (40 means BASIC is enabled) Maybe try programming Shoestring's memory tester replacement OS ROM to thoroughly test the RAM? You'll need to arrange the ROM image with BASIC in the right place for it to pass the BASIC test too. XEGS 32KB ROM offsets for 27256: $0000-$1FFF - 8 KB Missile Command $2000-$3FFF - 8 KB BASIC $4000-$7FFF - 16 KB Operating System
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Hmm all 8 drams replaced eh? Hmm... maybe a bad socket or some other component as you suspected. The original sockets are only single wipe and might not provide good contact if broken, corroded, etc.. Might be interesting to see what happens with a tool such as Shoestring's RAM tester which is a replacement for the OS ROM - if it is able to present anything up on the screen at all, and if it might provide further hints. It would be for a 27c128 type EPROM. If you don't have the means to program one PM me I can drop a programmed one in the mail.
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800XL Troubleshooting - dies after 30 seconds or less
Nezgar replied to telmnstr's topic in Atari 8-Bit Computers
I'd duplicate the OS in both halves of the 27C256 - I've had spurious crashes probably due to some spurious activity on the highest address line causing it the "bank switch" otherwise. Also, I guess now you can try programming Shoestring's RAM tester to it? (Repeated 2x) -
800XL Troubleshooting - dies after 30 seconds or less
Nezgar replied to telmnstr's topic in Atari 8-Bit Computers
I'd consider socketing the OS ROM... It's not unheard of to fail, but definitely less prevalent compared to say an XEGS. Since you have a known good one from another system, you can rule that out quickly once socketed. Another benefit if you socket the OS is then you could easily swap in an EPROM programmed with Shoestring's RAM tester to see if it highlights anything specific, or other OS's on EPROM in the future. I can program and mail you one if you like - PM if interested. Or even better wait until you've tried swapping your OS ROM's first. If it turns out your OS ROM is BAD I can send 1 of each... -
@matirwin Since you've done all the tests I can think of, short of swapping an OS ROM from another machine which you indicated you don't have, if you like you can PM me and I can program and mail you a replacement OS EPROM to try... Another remote possibility is bad RAM or MMU... I could send a 2nd chip programmed with Shoestring's RAM tester as well to eliminate that possibility.
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The nice thing about the Shoestring RAM tester, or the Sys-check plug-in board's tests are that it tells you which chip is bad - the built in self test can not help you determine that... Otherwise you have a tedious trial and error task of finding out which combination of 8 chips out of the 32 you have result in green dots...
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If you're interested, PM me and I can mail you a replacement EPROM programmed with the stock XL OS. I can also send you a second EPROM programmed with Shoestring's RAM tester to further diagnose the system.
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800XL hangs at blue screen with cursor
matirwin replied to matirwin's topic in Atari 8-Bit Computers
I burnt the rom and I can get the computer to start now without a cart, but not at initial power up, only on a reset. It still hangs on initial cold start. I also did burn the shoestring ram tester as suggested above by @Nezgarand that passes, as does the built in system check (memory , audio/visual and keyboard all work) which now starts when I press the option key. Maybe the power supply is sketchy and cant give enough juice to get the machine running? I tested it while running and its 4.94v. Not sure what the spec is for these (its just barely over 5v with it not being connected to the machine). I am going to replace that power supply in either case. At least it functions (or enough to use) now.
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