C64 reports xxx bytes free

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rhurst
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C64 reports xxx bytes free

Post by rhurst »

There is this later "C" model that mainly shows 11 - 211 bytes free. Very occasionally, it will report 38911 (or something very close to that). I have not tried POKE-ing the expected normal BASIC values, to override the startup ramtas routine, but everything else is functioning fine.

Anyone want to take a stab at what the probable cause is? Bad RAM? Bad power? Poltergeist? Just curious.

If it is something that is "fixable", please advise. I wouldn't mind spending some money on this particular unit.

Or, has anyone used its chassis as a mod for their VIC 20? This case/keyboard is in mint condition, and it would be a shame not to be able to put it to towards some "practical" use.
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ral-clan
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Post by ral-clan »

Have you tried the obvious: reseating the all chips - and barring that working, pulling them and cleaning the chip legs?
rhurst
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Post by rhurst »

There's only a few socketed chips, and all are tightly seated; I suspect the RAM is soldered to the "mobo". :oops:

Interesting, if I power it up cold, it instantly displays and reports anywhere from 11 - 8099 bytes free. But after, if I quickly shut it off-and-on, it takes the expected 2-seconds to display and report all 38911 bytes free. Could that be a capacitor not charging fully from a cold start? :?

I took photos if anyone wants a looksee:

WHOLE
Image

LEFT
Image

LEFT-MIDDLE
Image

RIGHT-MIDDLE
Image

RIGHT
Image
Last edited by rhurst on Sat Feb 07, 2009 1:42 pm, edited 1 time in total.
Leeeeee
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Post by Leeeeee »

The RAM is the two OKI M41464 chips just above the words PCB ASSY NO. It all looks ok but that is often the case.

If you have a meter make sure there is 5V at the RAM chips, 0V is pin 18 and the 5V supply is pin 9.

Lee.
channelmaniac
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Post by channelmaniac »

Those are standard 4464 type DRAM chips. I have them on my website if you need some.

RJ
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6502dude
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Post by 6502dude »

.....and how does this fit into Vic-20 hardware section? :lol:
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rhurst
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Post by rhurst »

Thanks for all the replies ... I will get and put a volt meter on it. If the reading is nominal, I suppose I need to then de-solder them from the board, and get replacement chips ... :roll:
.....and how does this fit into Vic-20 hardware section?
:oops:

Let's see, I have this close friend, VIC, that has to take care of his older brother, who is showing signs of dementia ... :P
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