test-drb January 2012

test-drb@ccmp.vtda.org

201 participants
274 discussions

by john＠yoyodyne-propulsion.net

Mr Zoidberg, Thank you for bringing that error to our attention. John Stupid John (or web designer) has met with an unfortunate accident. On Tue, Jan 31, 2012 at 11:25 AM, <quotes at nospam.com> wrote: > First Name: JohnA > Last Name: Zoidberg > Email: cctalk at classiccmp.org > > City: > State: > Zip: > IP: xxx.xxx.xxx.xxx > Evil Plan: Your logo says "Yoyodyne Propolsion Systems", not "Yoyodyne > Propulsion Systems" > -- Yoyodyne Propulsion Systems: "The Future Begins Tomorrow" Visit us at: http://www.yoyodyne-propulsion.net -------- "Yes, Obama duped young people by not doing every single thing they want. So now, they'll all vote Republican. It's like when I want some bread, I won't settle for half a loaf. Instead, I will have a muffin made of broken glass." -Stephen Colbert

12 years, 2 months

Commordore 64 character color cycling

by dm561＠torfree.net

Original Message: Date: Mon, 30 Jan 2012 11:59:44 -0700 From: Kevin Reynolds <tpresence at hotmail.com> > I know following up your own request is kinda taboo, but I should have > shared more information... > I am guessing that the problem is with the Color RAM (SRAM) in slot U6. > This model of C64 has socketed components, but I am not sure U6 is one of > these. The other possible issue is PLA U17. As the problem never goes > away, perhaps it is more than this. > Is there a good vendor to get replacements this late in the game? > Kevin Try here: http://www.arcadecomponents.com/catalog/item/3054735/8335676.htm

12 years, 2 months

Troubling Olivetti M24 Monochrome Monitor

by hendrikvandewerken＠gmail.com

Since a few days the monitor of my Olivetti M24 displays a bright spot in the middle of the screen when the system is switched off. I suspect the screen will be soon damaged this way. I know there is a circuit in CRT monitors that prevent this. But I don't know where to look on the circuitboard. I did check the parts on the print on the tube base: they seemed to be alright, so now I'm stuck. Does anyone has a clue for me how to proceed?

12 years, 2 months

Opening the Mac M0001 case

by wheagy＠gmail.com

I allowed the case to sit overnight, and when I tried it again today, it came apart much easier...about like I expected. The floppy mechanism was definitely gummed up. It didn't appear to be damaged so I lubed it and reassembled and it works great again. Thanks for the info. Win > Something happened to the floppy drive. It worked fine for a long time, but now will not allow a disk to be fully inserted. It goes it about all but the last quarter inch. I can't see the problem by looking through the slot, so it looks like I need to get inside. The case just seemed much harder to open than I expected, so I wanted to make sure I didn't break anything. I'll be careful to stay away from the high voltage innards. >That's quite a common issue on the original 'auto-inject' drives. They were greased with this god-awful white grease stuff that turns to gooey sludge over the course of time and jams the mechanisms. Best advice is to remove it, see if it's physically damaged (I've had parts bend in them when they jam) and if it seems okay clean and re-lube the mechanism and see if you can get it moving again.

12 years, 2 months

Apple II Colour Demodulator

by thrashbarg＠kaput.homeunix.org

Hi, This might interest someone here, so I thought I'd post it. I've been working on a colour demodulator for my Apple //c. It converts the output to component video suitable for any television with component inputs. The original composite output of the //c becomes the luminance input and the circuit extracts the red and blue difference signals. It's not 100% perfect but it does display colour that mostly resembles the original NTSC colour palette. http://kaput.homeunix.org/appleii or http://kaput.retroarchive.org/appleii If you have two MC1496's, feel free to build it. I'd like to see if it works unmodified (or with any modifications) on an NTSC model Apple ][ or //. The reason why I made this is because I don't have a PAL modulator for my //c. My television does support NTSC, but the Australian version of the machine doesn't output the correct timings for NTSC... it was designed to be attached to the PAL modulator. Cheers, Alexis.

12 years, 2 months

11.98135 MHz crystal applications

by fraveydank＠gmail.com

Anyone know what this frequency is for? I have a crystal in my bin of pulls, no idea what I pulled it from (my guess would be an old dead ISA modem or sound card, given where most of my pulls came from). It doesn't divide nicely into NTSC or PAL color subcarriers (my normal assumption for weird frequencies), but it it's still a pretty common part. The one place I found it mentioned that wasn't a datasheet site had something (maybe) to do with DTMF decoding: http://ohlandl.ipv7.net/communications/Gammalink.html Any ideas? - Dave

12 years, 2 months

Looking for 8080/Z80 BASIC

by dm561＠torfree.net

----- Original Messsage: Date: Fri, 30 Dec 2011 22:43:21 -0800 From: Josh Dersch <derschjo at mail.msu.edu> Anyone have any recommendations for a reasonably featured 8080 or Z80 BASIC? What I've got running at the moment is a mongrel IMSAI 8080 with a Z80, 48K of working memory and a serial port. My eventual goal is to get CP/M running on it (I have a Cromemco 64FDC -- anyone know of either an official CP/M for this or know of a BIOS that supports this controller before I start writing my own?) but for the time being I thought it would be fun to get a BASIC running on it. <snip> Thanks, Josh ----- Reply: Just curious: Does your memory configuration support swapping out the RDOS boot/monitor ROM? And what drive(s) do you have connected? As you probably know, the FDC supports 5.25"DD as well as 8" and the 3.5 and 5.25" HD equivalents. I haven't seen any standalone BASIC versions for the FDC; there are at least two versions of BASIC for the Cromemco, but AFAIK they both require a bootable CDOS disk. However, unless they use any of the extra calls in CDOS I wouldn't be surprised if they worked just as well with CP/M. In addition to Cromemco's CDOS CP/M equivalent AFAIK there were also at least two official third-party CP/M implementations for the FDC and one or two hacked BIOSes, but there may be compatibility issues among the three different versions of the FDC. Interesting though; I'll have to look around...

12 years, 2 months

Opening the Mac M0001 case

by wheagy＠gmail.com

HI, Can someone give me the Cliff Notes version of opening the M0001 case? I removed the five screws from the back (including the two deeply recessed screws) but the case is just as tight as when the screws were in. What am I missing? Thanks...Win wheagy at gmail.com

12 years, 2 months

Starting point for diagnosing unhappy Commodore 1581 drive?

by derschjo＠mail.msu.edu

As if I needed another project, I picked up a 1581 yesterday at SRCS in unknown condition. Hopefully this won't distract me from my Cromemco floppy issues for too long :). The power switch was broken (permanently stuck in the "off" position) so I replaced it with one from a "parts" C-64. Once that was repaired the symptoms I'm seeing are: - Both LEDs on the front come on and stay on permanently. My understanding is that the access light should turn off after about two seconds. - If the drive is hooked up to my C128 at powerup, the 128 will hang after displaying the startup banner (I assume it's waiting for a response from the drive and not getting one...) - If a disk is in the drive, the disk will spin for a second or so and the heads will seek back to track zero. The last item makes it seem like the 6502 is running and that the EPROM contents are still valid. I dumped the EPROM and verified that its contents are correct against an image from the 'net. The power supply is a known-good & tested supply I've been using with a 1541-II. 5V and 12V supplies look fine. For good measure I've cleaned the sockets & pins for the EPROM and the WD1772 (the only two socketed chips). Anyone have any tips for narrowing down the fault before I start digging through the source listings & schematics? Thanks as always, Josh

12 years, 3 months

Opening the Mac M0001 case

by wheagy＠gmail.com

>How easy it comes of depends wether it's been removed many times before. First time removals >can be tight as hell. >Might I ask why you are removing the case bucket? Mark, Something happened to the floppy drive. It worked fine for a long time, but now will not allow a disk to be fully inserted. It goes it about all but the last quarter inch. I can't see the problem by looking through the slot, so it looks like I need to get inside. The case just seemed much harder to open than I expected, so I wanted to make sure I didn't break anything. I'll be careful to stay away from the high voltage innards. Thanks...Win

12 years, 3 months

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test-drb January 2012