Author
| D41254C-15
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jltursan
msx professional
Posts: 830 |  Posted: August 19 2007, 18:32 |
Anyone knows what kind of DRAM is it?. I guess that it must be a 64Kx4 IC; but I'm not sure. As for its datasheet, I can't find it nowhere on the web  |
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Jipe
msx freak
Posts: 184 | Posted: August 19 2007, 19:55 |
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jltursan
msx professional
Posts: 830 | Posted: August 19 2007, 20:01 |
Thanks for the suggestion!. The only clue I have is that the Sony HB-500 (the one with this kind of memory) has 2x41254 and it must be the RAM, not VRAM. This machine only has 64K; so having 2 pieces they must be 64Kx4 (the IC name is confusing); but there's a total lack of info about this machine or those IC...  |
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zeilemaker54
msx lover
Posts: 97 | Posted: August 20 2007, 08:40 |
If I am not mistaken, I think I have the servicemanual somewhere. I will look this evening and let you know!
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jltursan
msx professional
Posts: 830 | Posted: August 20 2007, 10:17 |
That would be great!  |
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Jipe
msx freak
Posts: 184 | Posted: August 20 2007, 15:35 |
i have this service manual (Thank's Hans Otten) and it's a 64k x 4 bits dynamic Ram
IC 48,55
MB81464-12 (Fujitsu)
TMS4464-15NL (TI)
µPD41254C-12 (NEC)
µPD41254C-15 (NEC)
µPD41464C-12 (NEC)
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jltursan
msx professional
Posts: 830 | Posted: August 20 2007, 16:02 |
So, looks weird that Sony used two different brand memory ICs (being all the same 64Kx4) in this machine, Fujitsu for VRAM and NEC for the main RAM.
Thanks for the info! |
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dhau
msx master
Posts: 1047 | Posted: August 22 2007, 05:52 |
Well if it's really old computer, you may have slower ram for vdp, since it was cheaper, yet performed fine.
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jltursan
msx professional
Posts: 830 | Posted: August 22 2007, 10:20 |
In fact, then HB-F500 has slower DRAM as main RAM (150 ns), the VRAM is a bit faster (120 ns). The 81464 are very common IC; but I've never seen before the 41254...
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dhau
msx master
Posts: 1047 | Posted: August 22 2007, 18:54 |
41256 dram chips are great for two things:
1) upgrade IBM PC XT with pre-1985 motherboard to full 640KB
2) upgrade Atari 130 XE to 320KB RAM |
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nikodr
msx addict
Posts: 449 | Posted: August 22 2007, 19:46 |
Quote:
| 41256 dram chips are great for two things:
1) upgrade IBM PC XT with pre-1985 motherboard to full 640KB
2) upgrade Atari 130 XE to 320KB RAM
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"640 kbytes ought to be enough for everybody".
So those 1985 personal computers must not be very good.I am glad though that those 41256 dram chips can help those poor old computers and make them live to the standar of 640 kbytes of ram.
haha |
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