_The Doctor__ Posted June 4, 2016 Share Posted June 4, 2016 (edited) Just pull, clean and re seat all of those chips and make sure they are all in the correct sockets to get started since the memory was replaced also... don't assume the memory you bought is good, I have bought memory and one or two chips were bad right out of the tube... since memory was bad... next stop mmu and delay line Edited June 4, 2016 by _The Doctor__ 1 Quote Link to comment Share on other sites More sharing options...
Kyle22 Posted June 4, 2016 Share Posted June 4, 2016 I have just re-installed a U1M in an 800XL, replaced every 40 pin chip, and every TTL 74LSxxx chip. I swapped U1Ms with a known working one. Swapped all RAMS with known working ones. Reset line seems OK at 4.53V (IIRC). That should be plenty high enough to be considered a Logic 1. And it still DOESN'T WORK! This can be very frustrating... Hang in there, We'll all get this sorted out eventually. Quote Link to comment Share on other sites More sharing options...
shoestring Posted June 4, 2016 Share Posted June 4, 2016 Reset needs to go Lo to Hi though. This is where a logic probe comes in handy to see if the 6502 is getting the right signal. Address and data lines should toggle. That's one of the first things I check when troubleshooting a dead machine. Quote Link to comment Share on other sites More sharing options...
flashjazzcat Posted June 4, 2016 Share Posted June 4, 2016 Exactly: it's jitter and noise on RST causing the issue remedied by the cap fix. U1MB goes into a reset state when the computer doesn't, causing IO RAM under the hardware region to turn off unexpectedly. Quote Link to comment Share on other sites More sharing options...
ClausB Posted June 4, 2016 Share Posted June 4, 2016 I drive past Perry every weekday and am willing to help. 1 Quote Link to comment Share on other sites More sharing options...
Timothy Kline Posted June 5, 2016 Author Share Posted June 5, 2016 I drive past Perry every weekday and am willing to help. I may invite you to! Thank you so much! Quote Link to comment Share on other sites More sharing options...
Timothy Kline Posted June 5, 2016 Author Share Posted June 5, 2016 Alright, another update on this dead 800XL. I finally came across a fully-socketed, fully working 800XL and have have been swapping out chips. Swapping out the OS CO61598B-01 got me to a BASIC prompt, woo-hoo! Now to track down a replacement chip and see what happens next. O.o --Tim 3 Quote Link to comment Share on other sites More sharing options...
shoestring Posted June 8, 2016 Share Posted June 8, 2016 You can use a standard EPROM instead of the original mask rom, you just need to get it programmed. 1 Quote Link to comment Share on other sites More sharing options...
Kyle22 Posted June 8, 2016 Share Posted June 8, 2016 Reset line slowly comes up. I'll try a 100pF cap before I pull all of my hair out and order a NEW MOTHERBOARD... I really hate to admit defeat, but this one is really kicking my ass. Quote Link to comment Share on other sites More sharing options...
Timothy Kline Posted June 8, 2016 Author Share Posted June 8, 2016 You can use a standard EPROM instead of the original mask rom, you just need to get it programmed. This is one of those subjects I've become increasingly intrigued by, but 30+ years on since Atari's heyday, what EPROM burners/programmers should I look into to handle ROM needs for my Atari 8-bit family? Is there a preferred/favorite model, specifically, that can handle most (if not all) of the ROMs of the Atari? --Tim Quote Link to comment Share on other sites More sharing options...
shoestring Posted June 8, 2016 Share Posted June 8, 2016 (edited) This is one of those subjects I've become increasingly intrigued by, but 30+ years on since Atari's heyday, what EPROM burners/programmers should I look into to handle ROM needs for my Atari 8-bit family? Is there a preferred/favorite model, specifically, that can handle most (if not all) of the ROMs of the Atari? --Tim You can use a standard 2464 eprom, but you will need a 2364 to 2464 adapter as the pinout is different. Save yourself the hassle and get the 2364 flash eprom replacement. There's a small fee included in the price if you want them to program an image of your choice. http://www.sellmyretro.com/offer/details/ROM-EL-2364-FLASH-EPROM-Chips-(replacement-for-2364-ROM)-2339 Edited June 8, 2016 by shoestring 1 Quote Link to comment Share on other sites More sharing options...
Timothy Kline Posted June 8, 2016 Author Share Posted June 8, 2016 You can use a standard 2464 eprom, but you will need a 2364 to 2464 adapter as the pinout is different. Save yourself the hassle and get the 2364 flash eprom replacement. There's a small fee included in the price if you want them to program an image of your choice. http://www.sellmyretro.com/offer/details/ROM-EL-2364-FLASH-EPROM-Chips-(replacement-for-2364-ROM)-2339 Thank you for the follow-up, Shoestring, although I'd be more interested in being able to do the programming myself as situations arise. Ideally, being able to program my own BASIC or OS chips. That's why I'm wondering what a person would look for in today's marketplace that could handle 8-bit (e)EPROMs-- presumably via USB? --Tim Quote Link to comment Share on other sites More sharing options...
shoestring Posted June 8, 2016 Share Posted June 8, 2016 (edited) Unfortunately I don't have an exact answer as I'm still using a very old EPROM programmer ( Micromaster LV48 ) which connects via the parallel port. It depends on your budget but I would definitely avoid some of the cheaper brands, you want something that can test ram chips and ttl series logic chips. The MCM68766 is pin compatible with the 2364 but you would be hard pressed to find something affordable that can program them directly. This is why you will need an adapter that will allow you to program them as a 2464 device, this is your best and most affordable route. The TopMax II would be one of my top choices if I were looking to replace my old one with, it's not cheap though! Edited June 8, 2016 by shoestring Quote Link to comment Share on other sites More sharing options...
Timothy Kline Posted June 8, 2016 Author Share Posted June 8, 2016 Unfortunately I don't have an exact answer as I'm still using a very old EPROM programmer ( Micromaster LV48 ) which connects via the parallel port. It depends on your budget but I would definitely avoid some of the cheaper brands, you want something that can test ram chips and ttl series logic chips. The MCM68766 is pin compatible with the 2364 but you would be hard pressed to find something affordable that can program them directly. This is why you will need an adapter that will allow you to program them as a 2464 device, this is your best and most affordable route. The TopMax II would be one of my top choices if I were looking to replace my old one with, it's not cheap though! WHEW-EE!! I can see what you mean about not being cheap... OR inexpensive! O.o --Tim Quote Link to comment Share on other sites More sharing options...
JoSch Posted June 8, 2016 Share Posted June 8, 2016 How about this one? http://www.ichbinzustaendig.de/dev/meeprommer-en Quote Link to comment Share on other sites More sharing options...
ClausB Posted June 8, 2016 Share Posted June 8, 2016 My old Shooter still works. It can program 27128 or 27128A for you and I'm local. Quote Link to comment Share on other sites More sharing options...
Kyle22 Posted June 9, 2016 Share Posted June 9, 2016 (edited) Just get a TL866CS. They won't do a 68766, but they're affordable and great for most newer stuff. Search here for my thread on the TL866 firmware upgrade hack to turn it into the more expensive 866A model. Use a 2764 in an adapter. Edit: Are we talking about BASIC or OS? I just saw your other thread. You only need a 68766 or a 2764 in an adapter if you are replacing the BASIC chip. The OS is a standard 27128 that is easily programmed with a TL866. Edited June 9, 2016 by Kyle22 1 Quote Link to comment Share on other sites More sharing options...
shoestring Posted June 9, 2016 Share Posted June 9, 2016 The numbers he posted seem to indicate the basic rom. But i'm also a little confused now. Quote Link to comment Share on other sites More sharing options...
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