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Forum Index : Electronics : CMOS 8k byte RAM chips
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| domwild Guru  Joined: 16/12/2005 Location: AustraliaPosts: 873 |
For data logging I intend to use an old PC-8201A NEC laptop. Runs on four AA size batteries or AC charger. There is room for more RAM chips as it only has 16k bytes of internal RAM and 32k bytes of internal ROM. I have counted the pins on the empty sockets, there are 2 x 14 pins. 1. As I cannot source the PC-8201-06 RAM chips (NEC) and I do not even want to try, are these standard chips I can buy anywhere and instal them despite the dire warning that I will lose my warranty?? 2. If these are standard chips, do I need to double them up or not, in other words, do I need to instal one or two?? 3. Will it be able to sense and use the extra chip(s) or will I have to open up the case more and fiddle with jumpers?? Thanks. Taxation as a means of achieving prosperity is like a man standing inside a bucket trying to lift himself up. Winston Churchill |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5036 |
Hi Dom. Could you have a look at the ram chips in the old NEC, I need the model number of the chips themselves. How many spare sockets do you have? Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| domwild Guru Joined: 16/12/2005 Location: AustraliaPosts: 873 |
Glenn, Happy Easter! Thanks for reply. Will open up the case and let you know. The last one is called RAM7, the ROM Basic chip I can have a look at but not the installed RAM without opening the whole thing up. Looks like 6 or seven spare sockets in the separate ROM/RAM compartment. Taxation as a means of achieving prosperity is like a man standing inside a bucket trying to lift himself up. Winston Churchill |
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| WindChopper Newbie  Joined: 08/02/2007 Location: United StatesPosts: 15 |
Hi Dom Google'd "PC-8201A NEC laptop" Came up with .... http://www.planetserver.net/nec-notebooks/inventory.html 8k RAM Module for $29.00 + Shipping. Also claims to have manuals, etc .... Also http://www.obsoletecomputermuseum.org/nec8201a/ .... looks like an old RadioShack Model 100 that I once owned. Don't remember much about it, other than in its day, it was a nice Laptop if you did not mind the 40 char per line display. Should make a reasonable logger, you tend to forget just how much you could accomplish on some of these old BASIC based machines! Found a couple of old HP OmniBook 800's cheap with the same idea in mind. Another project in the pile waiting for the time to .... Happy Easter to all .... Russ |
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| domwild Guru Joined: 16/12/2005 Location: AustraliaPosts: 873 |
Russ and Glenn, Thanks for answer. Opened up the case but found too many chips in there, copied some numbers but I never saw anything as orderly as in the old XTs, where there were 8 + 1 (for parity) chips and even I knew that those were the memory chips. Opened up an old NEC P6 dot-matrix printer and it has a few socketed chips, with numbers like: D23C256EC 172 and when I google this number, the whole world wants to sell me this chip without telling me what it is!!! Anyway, will try the site Russ is suggesting, thanks. Taxation as a means of achieving prosperity is like a man standing inside a bucket trying to lift himself up. Winston Churchill |
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| RossW Guru Joined: 25/02/2006 Location: AustraliaPosts: 495 |
From memory, a 23C256 is a 256Kbit (32 K-bytes) ROM (mask programmed) and probably contains the code the processor in whatever the device is, needed to run. Its been a long time, but 23* were mask-programmed, 25* and 27* were EPROM (erasabe, programable read-only memory) 'C' denoted 'CMOS' technology The last numbers were the size in Kbits. 2708 was an 8 kilobot (1 Kbyte) erasable chip, a 25C64 was a CMOS 64Kbit (8Kbyte) eprom. I stopped using them about the time the 27C1024 (If I recall correctly) came out. Nowdays, nobody bothers with most PROMs, they just stick flash in (often *IN* the main processor fabric). |
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| WindChopper Newbie Joined: 08/02/2007 Location: United StatesPosts: 15 |
Hi Dom In a fit of early morning "Blazing Stupidity" ( I do Blazing Stupidity well ), I went back to look a little more .... ( fond memories of the R/S Mod 100 or something like that ). Found this as a general FYI that may be worth saving .... http://www.ordersomewherechaos.com/rosso/fetish/m102/web100/ docs/kyocera-faq.html Also found this listing, which I'm not sure is a current listing or not .... http://cgi.ebay.com.au/Collectable-NEC-PC-COMPUTER-PC8201A-T ake-a-L-K_W0QQitemZ300093103615QQcategoryZ736QQcmdZViewItem It claims to have 32k of memory in it .... which seems to be max'd out memory from what I found. Most of the information that is still on the web is 10 years old, a couple of what appear to be better information links are dead. Never did find any mention of the chip type number for the memory chips themselves, but I suspect that you would need a special carrier board to mount them anyway. IMHO .... I'd just find a way to use it as is, or look at that ebay.au unit. Well now that I'm awake, it's time for coffee, shower, shave, and off to work. Later .... Russ |
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| domwild Guru Joined: 16/12/2005 Location: AustraliaPosts: 873 |
Russ, Thanks for that. For the price of US$29+freight, I can add much more memory to my Picaxe and log there and only transfer totals to the old NEC laptop. I managed to add memory to the I2C bus of the Picaxe 28X proto board, I think it is 32 or 256kB and even managed to test drive it, so I think I will stick with that. I was under the mistaken belief that those chips are perhaps standard chips, 28 pin, CMOS, 8K, something one can still buy at Jaycar, Dick Smith, etc. Thanks for your help. Taxation as a means of achieving prosperity is like a man standing inside a bucket trying to lift himself up. Winston Churchill |
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| manuka Newbie Joined: 18/12/2006 Location: New ZealandPosts: 19 |
The PC-8201A was the NEC version of the far more popular Radio Shack Model 100, so try looking for parts for the latter too. I had in fact such a Model 100 in 1985-86 & was a great fan, BUT that was >20 years back! There are far better approaches from the late 90s serial PDA era that are now often "free to a good home" - Casio Pocket Viewers & Sharp Wizards being my recommendations. These usually have at least 1Meg of Flash RAM & batteries last AGES ( 180 hrs on Wizard I recall). See =>www.picaxe.orcon.net.nz/wizard.gif and =>www.picaxe.orcon.net.nz/pvdemo.jpg |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5036 |
Since we are taling about old computers, I still have my first real computer, a 1982 Microbee. Came with 16k ram that I upgraded to 32k. I'm sure some of our older members will remember them. I even found a Microbee emulator for PC a few months ago, brought back memories. I think the old Bee still works, last time I used it was a couple of years ago and then I wrapped it in plastic to keep the roaches out. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| domwild Guru Joined: 16/12/2005 Location: AustraliaPosts: 873 |
Thanks once again for the replies. Regards, dominic Taxation as a means of achieving prosperity is like a man standing inside a bucket trying to lift himself up. Winston Churchill |
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