C64 reports xxx bytes free

rhurst · Post by **rhurst** » Sat Feb 07, 2009 6:20 am

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.

ral-clan · Post by **ral-clan** » Sat Feb 07, 2009 7:17 am

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

rhurst · Post by **rhurst** » Sat Feb 07, 2009 11:22 am

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

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

LEFT

LEFT-MIDDLE

RIGHT-MIDDLE

RIGHT

Leeeeee · Post by **Leeeeee** » Sat Feb 07, 2009 11:47 am

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 · Post by **channelmaniac** » Sun Feb 08, 2009 10:51 am

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

RJ

6502dude · Post by **6502dude** » Sun Feb 08, 2009 7:39 pm

.....and how does this fit into Vic-20 hardware section?

rhurst · Post by **rhurst** » Mon Feb 09, 2009 3:44 am

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 ...

.....and how does this fit into Vic-20 hardware section?

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