shoestring
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Posts posted by shoestring
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I checked completed listings to see what these are fetching for these days on eBay AU. Ridiculous.
I remember you couldn't even give these away. I picked up a working C128 for $5 at cash converters back in the mid 90s and there were breadbins & Cs taking up most of the rack space in the computing section. I bet most of them were thrown out.
I should have bought the lot of them
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A bridge between pins 5 and 4 shouldn't damage the RAM.
But you might want to check all of them again individually to make sure.
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6 hours ago, mksmith said:I've got my eye on a mint condition Vic 20 CR - currently $364 AU with a few hours left.
Way too much.
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Not sure where you going to get original non enhanced mask roms from. Alternatively, you can contact Steph at Eprompro and he can program the ROM chips you need.
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1. You don't need the original mask roms, you can program some EPROMs to take their place. There's a guy in Canada who does this as a service, just tell him what you need and provide the binaries and he will send you the chips. I believe you can use 2764s for video and program roms.
But I'd save yourself the trouble and just get a kit from here for $25 which will end up being much cheaper. You get the roms, stickers and the 65C02 which will bring your machine up to Enhanced specs.
https://www.reactivemicro.com/product/iie-enhancement-kit/
2. If you think the issue is mechanical swap over the keyboard from your other IIe and see if the keys work .If its not a mechanical issue, reseat the keyboard decoder next to the connector ( UE14 ) or swap it and see if that resolves. Also check your ribbon cable as well.
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There's an issue with the boot sequence and the machine isn't starting.
Check the F8 ROM first, then the AppleSoft ROM EF. ( locations D8 and D10 ).
Did you remove all socketed chips prior to dishwashing ( that's never a good idea ) ?. Check that you didn't bend any pins re-seating.
Similar issue at the link below with an Apple II & language card installed. So I would suspect the above ROMs or supporting logic fault. If replacing the ROMs doesn't fix it I'd suspect the two buffer ( 74LS244 ). If you have a scope or logic probe handy, you can check that the two enables are active ( pulsing ) on the above ROMs or just check the output of the MMU ( pin 19 and pin 20 ), if no pulsing then I'd assume replacement MMU is no good assuming the clock is good which appears it is.
https://forums.macrumors.com/threads/apple-ii-plus-language-card-error-please-help.1699921/
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Does it beep with the speaker connected on reset or powering up ?
Sounds like it's stuck in graphics mode. May be an issue with the logic chips which supports signals for softswitches. Check the IOU as well by substitution.
Do you have a photo of the board and the screen ?
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Plenty of light is important too. I have a USB scope which helps locating these types of things.
Is your c64 working now ?
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/RAS and A0 should not be bridged. Most likely happened when you installed the sockets. If they were not installed flush against the board, then it's likely solder has built up in between pins 4 and 5 on the component side and the two connections have been bridged.
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Not sure how I missed this one. They released it in January.
Love the Drax tune.
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Yes. This is my 65XE below which I practically rebuilt ( if you're wondering about the sockets ).
Atari did use the 130XE PCB in later 65XE models, presumably to save costs and just use the same PCB layout for both. As you can see the 2 other rams and EMMU are missing.
And a 130XE with 4 x 4464 dram.
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This should also work in some XEs and the later Apple IIes ( Platinum board ) with the two 4464 DRAM configuration.
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I don't have this problem with my Antonia. But I have to wait at least 3-5 seconds for the 65XE which now has TMS branded DRAM after a repair.
My previous Apple IIe enhanced needed 20 seconds, sometimes 30 or it boots to junk. My current one doesn't. In any case, the user guide even states that you should wait half a minute in between power cycling.
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3 hours ago, xrbrevin said:for reasons unknown, atari did not connect the chroma signal to the monitor port. this results in s-video being monochrome.
To save money on some parts. That can be the only logical conclusion.
Just look at the insanity in deciding the fate of the monitor port in the NTSC 600xls. Whilst other competitors still kept
it intact on their cheaper line of machines.
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It could be the socket. But I'm betting on one of the two chips being faulty.
In any case, replace both ( I would ). They're so cheap and common, like 0.50c each.
https://www.digikey.com/product-detail/en/texas-instruments/CD4051BE/296-2057-5-ND/67305
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Without me thinking about this too much, if your machine is socketed then try reseating or swapping the two 4051 analogue keyboard multiplexers ( C4051BE ) and see if the problem moves to other keys. That's usually the most common fault after the mylar and the keyboard followed by the POKEY ( much less likely ).
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I have the platinum NTSC international motherboard which has the 50hz PAL IOU ( 344-022 ) and would like to convert to proper NTSC specs.
Please contact me if you have any spares you could sell.
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I thought he was referring to a vertical shooter on the c64 not on the A8.
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On 7/25/2019 at 10:09 AM, Nezgar said:Already mentioned, but I also agree keep the DIN cord. Soldering that cord's 2 wires to a replacement common 5V DC power supply (ie a USB charger) of at least 1.5-2.0A is a lot easier than soldering wires to a new DIN connector...
The Sony PSP-100 charger is 5v and good for 2A. Just watch out for the knock offs on eBay.
The only issue with these USB type chargers is that there is some switching noise. The spare PSP charger is a little bit noisy compared to the power supply I rebuilt.
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Still sounds great and better than no sound at all.
I hear that fpgasid is pretty accurate but not exactly cheap!!
Enjoy!
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OK, so you're getting sync. Do you have a cart to try ?
You could try the OS ROM, MMU first, CPU. Then RAM.
You'll have to shotgun it if you don't have any troubleshooting tools.
You could try installing chips from your 600xl into your good 800xl, until you break it.
I think that's easier then doing the opposite as dead machines can hide many faults.
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13 hours ago, krslam said:Per Bil Herd, the epoxied PSU was a safety feature intended to prevent the units from catching fire. It wasn't for any sort of proprietary reason. Still a bad idea, though.
I remember how hot to the touch those power supplies used to get in summer.
And most people just left them plugged into the outlet 24/7, even when the machine wasn't running.
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c64: poor quality?
in Commodore 8-bit Computers
Posted
That ‘joke of a general home computer’ happened to have sold 10s of millions of units. If it were really as bad as you say it was then they wouldn’t have sold nearly as many.
It was great for the price, bundled with really good software and despite its shortfalls made home computing affordable for families like mine. During Christmas of 85, the IIe cost over $2500 AUD for basic system, the TI and the 800XL was in the $800-$900 price range and you just got the machine with a power supply + tv modulator .
What did I get for $499? The c64, dataset unit, user guide, 4 really good programming books by Phil Cornes, 6 games plus a cart. Sounded like a much better deal to us and in hindsight it definitely was. That c64 lasted me until I bought an Amiga in 1990, so much for unreliability ?
Regarding the cardboard shielding in the first models. Nobody ever seems to mention the proper metal shielding Commodore switched to in the later C models which also acted as a heat sink for all the major chips, increasing the reliability of the machine.