Colleton Posted September 10, 2019 Share Posted September 10, 2019 I received an early production (3-16-82) 800 today with a cased OS board, a cased 16K RAM board, and an uncased Mosaic 32K RAM board. I'm assuming that the computer originally shipped with 16K of RAM and the Mosaic board was added later. Sadly, the cased 16K board was bad, causing the machine not to boot, so I've removed it from the system. My question, and I'm pretty sure that I already know the answer, is with the Mosaic board installed can I install two 16K boards and have 64K of useable RAM? Or does the 800 OS not support 64K? I'm thinking it does not, but thought I'd check to be sure. Thanks! Quote Link to comment Share on other sites More sharing options...
+Nezgar Posted September 10, 2019 Share Posted September 10, 2019 34 minutes ago, Colleton said: I received an early production (3-16-82) 800 today with a cased OS board, a cased 16K RAM board, and an uncased Mosaic 32K RAM board. I'm assuming that the computer originally shipped with 16K of RAM and the Mosaic board was added later. Sadly, the cased 16K board was bad, causing the machine not to boot, so I've removed it from the system. My question, and I'm pretty sure that I already know the answer, is with the Mosaic board installed can I install two 16K boards and have 64K of usable RAM? Or does the 800 OS not support 64K? I'm thinking it does not, but thought I'd check to be sure. Thanks! The 800 OS technically supports up to 52K RAM, but generally most software will expect no more than 48K. Your best bet is to repair or replace the 16K board to get it back up to 48K and you should be able to run the majority of software. 64K was really only a 'thing' for the later XL/XE models which could disable the ROM to allow access to RAM sharing the same address locations. 2 Quote Link to comment Share on other sites More sharing options...
Faicuai Posted September 10, 2019 Share Posted September 10, 2019 54 minutes ago, Colleton said: I received an early production (3-16-82) 800 today with a cased OS board, a cased 16K RAM board, and an uncased Mosaic 32K RAM board. I'm assuming that the computer originally shipped with 16K of RAM and the Mosaic board was added later. Sadly, the cased 16K board was bad, causing the machine not to boot, so I've removed it from the system. My question, and I'm pretty sure that I already know the answer, is with the Mosaic board installed can I install two 16K boards and have 64K of useable RAM? Or does the 800 OS not support 64K? I'm thinking it does not, but thought I'd check to be sure. Thanks! If you are asking LINEAR RAM (accesible without the need of "banking"), then it can do up to 64 KBytes, as long as you know what your are doing (ClausB obviously does): As for Banked Ram, well, it can do quite a lot... (in relative terms, that is, because 1MB is a drop-in-the-ocean, in today's standards). Quote Link to comment Share on other sites More sharing options...
Colleton Posted September 10, 2019 Author Share Posted September 10, 2019 Okay, 48K it is. Thanks guys! 1 Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted September 10, 2019 Share Posted September 10, 2019 might wanna look up mosaic, and axlon ram cards as well, plug and play for the most part. Max ram? well some Atari cards add up to more than was available without some cajoling, still since it was present it still counts... You didn't need to cut the machine up to do any of the the memory configurations btw... Quote Link to comment Share on other sites More sharing options...
xrbrevin Posted September 10, 2019 Share Posted September 10, 2019 start a thread to request assistance with the mosaic - it might be an easy fix Quote Link to comment Share on other sites More sharing options...
BillC Posted September 10, 2019 Share Posted September 10, 2019 8 hours ago, xrbrevin said: start a thread to request assistance with the mosaic - it might be an easy fix He said the Mosaic 32K board was good, it was his cased OEM 16K board that failed. 1 Quote Link to comment Share on other sites More sharing options...
a8isa1 Posted September 11, 2019 Share Posted September 11, 2019 (edited) 19 hours ago, Colleton said: I received an early production (3-16-82) 800 today with a cased OS board, a cased 16K RAM board, and an uncased Mosaic 32K RAM board. I'm assuming that the computer originally shipped with 16K of RAM and the Mosaic board was added later. Sadly, the cased 16K board was bad, causing the machine not to boot, so I've removed it from the system. My question, and I'm pretty sure that I already know the answer, is with the Mosaic board installed can I install two 16K boards and have 64K of useable RAM? Or does the 800 OS not support 64K? I'm thinking it does not, but thought I'd check to be sure. Thanks! off topic: Back in the day it was learned that the cases could make the 16K boards overheat and lockup up the system. It was recommended that the boards be removed from their cases. One or magazines printed this information. My own 800 locked up after about an hour of use. When I did as suggested the problem was solved. I still have the 800 and it can be on for hours without a problem. Unfortunately, your board causing problems so quickly does not sound like an overheating issue. -SteveS Edited September 11, 2019 by a8isa1 Quote Link to comment Share on other sites More sharing options...
Colleton Posted September 11, 2019 Author Share Posted September 11, 2019 No, it isn't an overheating issue, although heat inside the case may have been what killed the chip. I just transferred the chips (in groups of 4) on the bad card over to a known good board in a known good 800. It ended up being a single RAM chip in the Z506 socket, 2nd from the right on the top row. I'd like to order one, but the P/N printed on the chip isn't generating any hit on digikey. P/N is: HM4716AP-4. Anyone know what P/N I should be looking for? Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted September 11, 2019 Share Posted September 11, 2019 (edited) https://octopart.com/hm4716ap-4-hitachi-2254862 https://www.questcomp.com/part/4/hm4716ap-4/216502456?utm_source=octopart&utm_medium=industry-cpc&utm_campaign=partsearch there are others manufacturers but the numbers are generally the same so drop the letters befor the 4716 and add the respective manufacturer letters.... MB8116E is another number stuck in my head search that up as well https://www.utsource.net/itm/p/8490811.html expensive at .47 a piece... :) Edited September 11, 2019 by _The Doctor__ 3 Quote Link to comment Share on other sites More sharing options...
AtariGeezer Posted September 11, 2019 Share Posted September 11, 2019 Or buy a backup card. https://www.ebay.com/itm/323830886185 2 Quote Link to comment Share on other sites More sharing options...
Colleton Posted September 11, 2019 Author Share Posted September 11, 2019 37 minutes ago, _The Doctor__ said: https://octopart.com/hm4716ap-4-hitachi-2254862 https://www.questcomp.com/part/4/hm4716ap-4/216502456?utm_source=octopart&utm_medium=industry-cpc&utm_campaign=partsearch there are others manufacturers but the numbers are generally the same so drop the letters befor the 4716 and add the respective manufacturer letters.... MB8116E is another number stuck in my head search that up as well https://www.utsource.net/itm/p/8490811.html expensive at .47 a piece... Awesome, thank you very much! Quote Link to comment Share on other sites More sharing options...
Colleton Posted September 11, 2019 Author Share Posted September 11, 2019 36 minutes ago, AtariGeezer said: Or buy a backup card. https://www.ebay.com/itm/323830886185 Ordered one yesterday, should have it in a week or so. Ordered 9 of the MB8116E chips as well. Quote Link to comment Share on other sites More sharing options...
Colleton Posted September 25, 2019 Author Share Posted September 25, 2019 Okay, the MB8116E chips I'd ordered from Utsource arrived today. Unfortunately the chips do not have the little U shaped depression at one end that you use to orient the chip in the socket. It does have a little silver square on what would be either the top left or bottom right of the chip. Pretty sure that it denotes pin 1, so it would be placed in the socket with the silver square in the upper left but thought I'd ask here before finding out the hard way. Any help/advice would be appreciated. FWIW, The RAM PCB is populated with both Hitachi ( HM4716AP-4 ) and Mostek (MK4116N-3GP) DRAM chips. I've looked at the datasheets for all three chip P/Ns and the pinouts of all three are identical. Quote Link to comment Share on other sites More sharing options...
+DrVenkman Posted September 25, 2019 Share Posted September 25, 2019 4 minutes ago, Colleton said: Okay, the MB8116E chips I'd ordered from Utsource arrived today. Unfortunately the chips do not have the little U shaped depression at one end that you use to orient the chip in the socket. It does have a little silver square on what would be either the top left or bottom right of the chip. Pretty sure that it denotes pin 1, so it would be placed in the socket with the silver square in the upper left but thought I'd ask here before finding out the hard way. It does. Quote Link to comment Share on other sites More sharing options...
Colleton Posted September 25, 2019 Author Share Posted September 25, 2019 Awesome, thanks! I'll give it a try this evening. Oh, FWIW, the MB8116E chips are Fujitsu. Quote Link to comment Share on other sites More sharing options...
Colleton Posted September 25, 2019 Author Share Posted September 25, 2019 Doesn't work. I tried 2 (out of the 9 chips I ordered) and got a black screen both times. Well, I have the spare 16K card and I've ordered a few of the Mostek chips from a seller on ebay. I'll try one of those when they arrive. Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted September 26, 2019 Share Posted September 26, 2019 (edited) swap chips into a known good card one at a time and you will find who's good and who's bad... after that take all of the tested good chips and put them all in all at once.... from there you can look for damage, bad support chips, cold solder joints etc... also remember to make sure the cards are in the proper slots on the 800 and facing the correct direction on install, while most card won't go in quite right the wrong way, you'd be surprised how some things 'made to fit' Pin one is marked, the dot goes to the 'u' side you were talking of. Edited September 26, 2019 by _The Doctor__ 1 Quote Link to comment Share on other sites More sharing options...
Colleton Posted September 26, 2019 Author Share Posted September 26, 2019 (edited) EDIT: I take that back. I just took a known good chip from a known good board and put it in the suspect board. Black screen. I put one of the MB8116E in the known good card and it worked like a champ. Obviously, I have something else wrong with the suspect board. Thanks for the help. Edited September 26, 2019 by Colleton Quote Link to comment Share on other sites More sharing options...
Colleton Posted September 26, 2019 Author Share Posted September 26, 2019 Thanks for the help, Doc. I found a 2nd bad RAM chip. I would have sworn that the 7 remaining chips on the suspect board were good as I had placed a known good chip in the 8th socket during the initial troubleshooting and the board tested good at that time. All I can think is that I killed it somehow when I was swapping chips around. So, upside is that the original 16K board is working and installed in the 800 along with the 32K Mosaic board. I have a spare 16K board, 7 spare DRAM chips and 5 more on the way. I should be good on 400/800 DRAM chips pretty much forever now. /knock on wood Thanks again for the MB8116E suggestion. 47 cents a chip is hard to beat. 5 Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted September 26, 2019 Share Posted September 26, 2019 (edited) No problem, another Atari up and running and a happy user is an awesome day indeed! A pleasure. Edited September 26, 2019 by _The Doctor__ 3 Quote Link to comment Share on other sites More sharing options...
Like us on Facebook
Follow us on Twitter
AtariAge on Instagram
Watch us on YouTube
Chat on Discord
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.