I decided it was time to start cleaning house so I've been testing all my flat 128s. Turns out that four are good (two with 16K VDC and two with 64K VDC, yeehaw!), one is dead as a door nail and one is exhibiting a rather odd problem that I haven't encountered before and couldn't find listed on Ray Carlsen's website. I get a screenful of garbage when I boot in 40 column mode and yet everything is dandy when I boot into 80 column mode. I also tried to check to see if it had a 16 or 64K VDC (in 80 column mode) using "POKE DEC("D600"),28:POKE DEC("D601"),63:SYS DEC("FF62"):SCNCLR" and the screen filled up with garbage. I get the same screenful of garbage in 64 mode too. What is really boggling my mind is that 128 still works fine. I can change the background and border colours and everything. I'm stumped.
Anyone ever encounter anything like this? Suggestions?
Maybe your 40 column VIC chip is bad?
Keeping in mind that I'm a software guy, is there an easy identifier for the 40 column VIC chip? If so, I can try swapping one in from one of the other 128s to see if it cures the problem. I'm also boggling my mind trying to determine which SID chips are the most desirable.
Tomorrow I have to repeat the testing with 25+ 64s. Pity me.
I agree it sounds like VIC. Since you have 4 (*jealous*) working C128s, it should be easy to borrow a VIC to be sure. Only catch is something else could be wrong besides the VIC and you may fry a good VIC chip.
Since you also have a completely dead 128, you might want to try its VIC chip first. But the results would be inconclusive if that doesn't fix the problem.
Good luck!
Edit
The VIC should be labled 8564 since you're in Canada (NTSC). The other, 8563, also has two RAM chips in the RF case (assuming 16K VDC).
25 C64's :förvånad: LoL
I tried swapping 8564 chips and the problem remains. Any other ideas?
And while I'm asking questions, how many RAM chips would there be in the RF case near the 8563 if the machine has a 64K VDC? Is there a way to tell what size the VDC is by looking at it? I should probably open up one the 128s that I know has a 64K VDC and see what it looks like. Maybe tomorrow when I'm not so tired.
You should see how many disk drives I have. It's way past ridiculous. :(
Quote from: gklingerYou should see how many disk drives I have. It's way past ridiculous. :(
Ok - I'll bite - 37 Commodore branded drives as of my count just now. :)
Lance
Quote from: gklingerI tried swapping 8564 chips and the problem remains. Any other ideas?
And while I'm asking questions, how many RAM chips would there be in the RF case near the 8563 if the machine has a 64K VDC? Is there a way to tell what size the VDC is by looking at it? I should probably open up one the 128s that I know has a 64K VDC and see what it looks like. Maybe tomorrow when I'm not so tired.
You should see how many disk drives I have. It's way past ridiculous. :(
Try swapping the 8701 (U28) chip with a known working one.
There will always be only two chips next to the VDC 8563. The 64K RAM chips will be marked as 4464. 16K ones will be 4416's. Is there a part number on the VDC RAM chips like MB81416-12?
Well, the VIC access to memory is controlled by the MMU and PLA. The PLA is soldered but the MMU is socketed if I remember correctly. It should be located near the 8502 and Z80 and marked as 8722 (on chip) and U7 (on circuit board). If swapping the MMUs doesn't work, I'd guess you'd need some test equipment...
I never had a D(CR) 128 so I can't say about 64K VDC RAM. As I understand it, Commodore only made flat 128s with 16K. You should find daughter boards installed (mod kits) on your flat 64K units. If not, take photos!
Quote from: adminQuote from: gklingerYou should see how many disk drives I have. It's way past ridiculous. :(
Ok - I'll bite - 37 Commodore branded drives as of my count just now. :)
I wasn't trying to start a competition but as long as we're counting, I have more than 37 1541s. Throw in 2 x 1541c, 4 x 1541-II, 11 x 1571s, 7 x 1581s and quite a few IEEE drives and you're starting to grasp the problem I'm dealing with. What happens is that every time I see an advert for some C= equipment, I buy the stuff. Sometimes it's a 64 and a 1541 and other times it's a huge lot. I just can't help myself. I've vowed to winnow the collection and sell or give away the stuff I don't want by the end of November so I've got my work cut out for me. The trick is going to be figuring out what to keep.
Anyway, time for bed. When I wake up I'll crack all these buggers open and see what's cooking inside them. I'm going to get this 128 working no matter what it takes. It has become one of those things I just can't let go of.
I have two flat C128s, 2 C64s, 1 C64C, 1 DTV, 11 1541s, 2 1571s, a 1702, a 1902a, and a Seikosha SP-1000, as well as assorted bits of miscellaneous hardware, and I thought *I* had a problem!
Thank you, guys, for making me feel almost normal. :)
BTW, I'm pretty sure that late model flat C128s also had 64K of VDC RAM. At least that's what I read on the InterTubes. I've never seen one myself. If so, I'd sure like to see a serial number range for those. It would make trolling eBay for them much easier.
Quote from: airshipThank you, guys, for making me feel almost normal. :)
A storage house, my own house, one car, and one storage facility. Too much stuff! But nothing in comparison with Bob Kadylo's warehouses and ship containers in Edmonton, Alberta, Canada. :-)
Truly,
Robert Bernardo
Fresno Commodore User Group
http://videocam.net.au/fcug
I hope you guys are all making arrangements for this stuff when you die, especially the unusual items. I'd hate to see it all trashed. Heirs are unlikely to know what is rare and what is common. In any event, you should make the effort to find ALL of it a good home when you're gone.
My Dad collected railroad antiques and he left me a complete list of everything he had, with prices that he updated continuously. It made my job a LOT easier! (Thanks, Dad!)
if any of you want to get rid of some stuff, let me know... I just got back into this after being out of the scene for about 15 years...
I have a C128 w/ 64k vid and the latest rom.. 2 1571's.. that need alignment and a good 1541 II, a 1084s a c2n data casette,2 suncom joysticks ( in less then good condition ) and I just picked up a C64 & 1541 with a 1702 monitor...
misc stuff, fast load cart, simon's basic cart, music machine cart, cp/m cartridge, incrediable musical keyboard c64 style and a copy of GEOS2.0
-----
I would still like to find a good 1581, a mouse! and a good suncom joystick... as well as jiffy dos for the C128.. I also need to pick up the
disk to align the 1571's..
Hope you don't mind me chiming in like this...
Quote from: airshipI hope you guys are all making arrangements for this stuff when you die, especially the unusual items. I'd hate to see it all trashed. Heirs are unlikely to know what is rare and what is common. In any event, you should make the effort to find ALL of it a good home when you're gone.
I second that! A good example is Ron Fick, who purchased Xetec's remaining stock of Lt Kernal hard drives and accessories. He passed away unexpectedly in 1999, and eBay's 94bravo, who runs the current Lt Kernal website (http://www.floodgap.com/retrobits/ckb/ltk/), has told me that as far as he knows, Ron Fick's family through his entire stock of Lt Kernal hardware in the trash after he died. :(
-Andrew
Maybe a trust should be setup, everyone adds a clause to their will that sends all Commodore stuff to the trust :-)
Mark
Quote from: strandedinnzMaybe a trust should be setup, everyone adds a clause to their will that sends all Commodore stuff to the trust :-)
Mark
That's not a bad idea! The trust should be set up as a non-profit entity and will allow a tax credit to the estate.
BTW, I am not an accountant but have probably the best accountant in New Jersey and I have learned a lot from him over the last 20 years.
Great idea!
-Jim
Quote from: strandedinnzMaybe a trust should be setup, everyone adds a clause to their will that sends all Commodore stuff to the trust :-)
I know where my C= goods will go. It's been written into my will.
Truly,
Robert Bernardo
Fresno Commodore User Group
http://videocam.net.au/fcug
More people should follow your example, Robert.
I will never again part with my C128... and my family is aware that of all the PCs in my house, the 128 is the most valuable.