ceratophyllum

Thanks, Rolo. Now I have one more thing to try before pulling out the soldering iron.

I bought a few cocos on eBay listed "for parts" and discovered they had no Extended Basic ROMs and that 24-pin eproms are not common. I found these neat 28 to 24 pin EPROM adapters for the C64 over at Retro Innovations. I didn't want to say anything until I had tested myself but all you have to do is flash an Extended Basic 8192KB ROM from MESS onto (for example) a 28-pin 2764, plug it in and you've got Extended Basic. No hex editing, soldering, or jumper wires...just flash and plug-n-play! I used the TL886CS USB eprommer with minipro and a 8KB ST M2764A-2F1.

I just got around to checking and I got 750 ohms across 1 and 16 for G pressed down. I tried F and O and got around 300 ohms. I think the problem is on the trace16 of the flat, cable sticking out because the resistance increases a great deal in just a few cm closer to the end. If I move the probe up the trace toward the keyboard (keeping the other end fixed, of course), the resistance is more like 360 ohms. I have seen this before with my other coco2 keyboard: oxidation or something eats these traces up. That one had it so bad you could see the break. I just tried painting over the high resistance section of trace with a CAIG Circuit Writer pen and went from I,O, J,K, N, M not working to all but O working. The ink takes a very long time to fully dry and the resistance of the wet ink is high. Maybe I'll wait another 24 hours before I check again.

I have F18A installed but I don't have Geneve 9640. (I've never seen one of those before. The Kmarts around here never carried them, LOL.) Can the menu system work on a regular TI, Extended Basic, PEB w/32KB (or nanoPEB). If it can, where can I find it? What's BOOT? I use CFMGR to browse the volume list and insert/remove volumes into DSK1-3. Funnelweb "DiskReview" to browse and launch the disk contents. CFMGR is not so good at loading EA5 games, often there is no text or a lot of graphics corruption. Launching from Disk review works a bit better. Can you point me to one of these disk images? I often get this when I start up with one of them in DSK1. I think I might have messed it up by shuffling things around or copying to CF7 400KB image. The games load in F'web diskreview, just LOAD is broken. GAMESDSK3.dsk

The keys press down on a sandwich of clear plastic sheets with some kind of conductive paint traces. -------top circuit sheet -------insulator sheet with holes under keys -------bottom circuit sheet The sheets are bound together in the corners so that they stay aligned. I gave the area around G a good spray of contact cleaner but the key is still not working. There is nothing special to the naked eye about that particular key's movement or the point it presses down on. Maybe I'll take out the 18 (no kidding!) tiny screws again and have a look with the ohmmeter. Not sure how I would fix a flakey trace...Circuit Pen, I guess.

With the 8 new 4164 chips, I get 24871. I have an Extended Color BASIC ROM in this system, no cartridges or other funny stuff inserted. According to the the instructions above, this is the right amount: Too bad the author doesn't say which issue and page of RAINBOW has the memory test program. I'll just play some games and see what happens.

The games seemed fine at first but little things were off like some letters were corrupted so I went ahead and soldered that jumper W1 (Figure 1 in the PDF below) and replaced them with NEC 4164 chips from eBay and now it is fully working except for the G key. The old chips have numbers: 8040517 8329 and Motorola "M" and Tandy Computers "TC" symbols. Coco2 memory upgrade instructions The May 1984 Rainbow (page 49) referenced above is also a very nice help for the confusing and hazardous (There are too many types of coco1 boards!) coco1 RAM upgrade. I just ordered some more 4614 RAM to upgrade my 16KB 26-3004A "NC Board" coco1.

I have a lot of game cartridges on disk. Most of them are supposed to be EA 5 loaded and I have been customizing FunnelWeb to use them on NanoPEB. I've tried a few games and they seem to load ok, except for DigDug which crashes if you get killed or complete the first level. Anyway, I was just wondering if there is something better/simpler than the F'Web CONFIGURE menu. (I think I've deleted most of the bits that are not needed just to have a menu and the capability to load EA5 PROGRAMs.) I know there are already lots of cool multicarts full of games; making things easier to find on my nanoPEB is just for fun. atari.dsk

Is there a way I can remap a key with a poke in immediate mode? I have extended color basic on a coco2 and my G key will not work. Would be nice to make some other key do ASC(71).

I sorta fixed one of these with "Wire Glue" and a short wire jumping across the bad section of ribbon cable. I say sorta b/c this water soluble glue is not very strong and I am hesitant to cover it up with epoxy because there there's no easy way to get that stuff off when something cracks again. As for the other with the bad "G" key, it looks like I am going to be spending some time poking around the inlay with an ohm meter.

I replaced the socketed 6821 with a 6822. The coco2 still doesn't work and the junk on the screen looks the same. I also tried another CPU. The screen got a little less fuzzy, but the pattern of vertical bars remained the same. I'm not in a huge hurry to unsolder the other 6822 and I'm still waiting on the socket to come in the mail. It was nice when one could just go to Radio Shack and get parts same day..... The SAM is also in a socket, but I don't know where to get a replacement except from another coco. Then there's the 8 RAM chips soldered to the board.

No idea what is the deal with the G key--cleaning did not work. The older keyboard has (most of the second row of the keyboard array (m n i j k l ) not working ) a broken trace in the ribbon cable. Maybe some conducting glue might fix it?

I tried a LOADMing a few games(Space Ambush, Cuthbert in Space) over drivewire and it looks like they work ok. Now if I could just fix the damn keyboard...Took all those tiny screws out, dusted it off a bit, and voila the G key still doesn't work. That plastic membrane sandwich looks like a really great home for mold and tiny bugs. Maybe I'll get a PS/2 adapter from cloud9....

I wrote down the wrong number above, it should be 6439. PCLEAR 1 PRINT MEM gives 11047 I'm also autoloading HDB-DOS 1.4 DW3 from a cartridge. So this is a 16KB system?

I recently got another almost-working coco2 and I think it has 16K ram. The RAM might be bad, because PRINT MEM gives a funny, small number: 6913. Everything on this coco2 is socketed so it should be an easy upgrade, if what I read here is correct. I just solder across a jumper and put in 8 4164s. But what is 4164? Is this the same part?