On Mon, 2 Sep 2002, Curt Vendel wrote: Gonna be at VCF? I'm pretty sure that there's at least one in one of the totes of stuff that I need to get rid of there. BTW, there was a later model (that I don't have) that was double density. I've got enough of a storage problem that I'll even have to turn down Sellam's offer to rejuvenate me with a Silent 700 :-( -- Grumpy Ol' Fred cisin(a)xenosoft.com

On Mon, 2 Sep 2002, Jeff Hellige wrote: There has been a fair amount of written material about how to interface them to other computers.

--- Sellam Ismail <foo(a)siconic.com> wrote: Serial, yes, but TTL-level sync serial, not RS-232. The C= IEC bus is quite well documented. I expect the Atari bus is, too. -ethan __________________________________________________ Do You Yahoo!? Yahoo! Finance - Get real-time stock quotes http://finance.yahoo.com

On Wed, 4 Sep 2002, Tony Duell wrote: AND,.. If I recall correctly, the Tandy Pdd1, although it was "almost RS-232" used TTL, NOT RS-232 voltage levels. There were some trivial adapters available to permit it to work with "real" RS-232 signals.

There's a lot more difference than that, and the voltage levels quoted are wrong, or at the very least, misleading. I don't have a copy of the relevant standards handy, so I might have some details wrong, but here goes... RS-232, which is now called EIA-232, is a single-ended signalling scheme. At the transmitter, the voltages are nominally around +12V (mark) and -12V (space), but are actually allowed to range from +25V to -25V. Aside transmitter including short-circuit protection. At the receiver end, voltages above +3V are considered a mark, and below -3V are considered a space. A signal between +3V and -3V does not meet the EIA-232 specs, so the behavior is undefined, but most receivers will consider a signal near 0V to be a space. The documentation is wrong. EIA-422 is a differential signalling standard. Rather than having a data signal referenced to ground, you have two signals referenced to each other, e.g., RxP and RxN for receive, and TxP and TxN for transmit. EIA-422 cannot interoperate with EIA-232 without a converter of some kind. However, the Macintosh ports also support EIA-423, which is a single-ended signalling method using levels approximately equivalent to those of EIA-422. In many cases EIA-232 equipment and EIA-423 equipment can interoperate (as is usually the case with Macintosh serial ports and EIA-232 devices), but technically an EIA-423 device does not in fact meet EIA-232 specifications. Another difference between EIA-232 and EIA-422 is that EIA-232 specifies a connector and the assignment of functions to connector pins, while EIA-422 and EIA-423 specify electrical characteristics only. Note that a device that uses an EIA-232 electrical interface but not the DB-25 connector is not actually compliant with the EIA-232 specification. For instance, devices with DE-9, modular, or MMJ connectors.

I hope you didn't interpret that as a personal attack. I know you were just trying to be helpful, and had undoubtedly gotten the information astray. Connecting EIA-232 directly to EIA-422 could let the smoke out of something, and we certainly wouldn't want that. On the other hand, I'm plenty interested in CoCo stuff, so comment on them all you like. I got my first Color Computer 2 back in 1984 or so, with 64K of RAM, a pair of TEAC FD55-F floppy drives (80 track double sided), a PBJ Word-Pak 80-column card, and some sort of PBJ backplane that did basically the same thing as the Radio Shack Multipak but was cheaper (and also less expensive). I ran OS-9 on it. After a while I added an RS-232 pak and one of the first USR Courier 2400 modems, so I could dial into a VAX running BSD 4.2. I don't recall now where I got a floppy controller, or what brand it was. Did Radio Shack sell the controller separately? I definitely didn't buy any Radio Shack drives back then, although last year I did buy some on eBay. Eventually I got a Coco 3, and gave much of my Coco 2 stuff to a friend, who has within the last two years given most of it back. I was surprised to learn recently that there's a SourceForge project to reverse-engineer, document, and extend OS-9 for the Coco: http://sourceforge.net/projects/cocoos9/ Also a package of command line utilities for Linux and MacOS X to access OS-9 disk images, and a cross-assembler: http://sourceforge.net/projects/os9tools/

Hi guyz I have a problem with the RF video output of some of my old micros. The use either american or Japanese version of NTSC on VHF/UHF, and all my equipment is PAL compatible. I have the same problem, with some old French micros, that use SECAM RF output only. I am looking for converters but I cannot find any. Could anybody help me? Thanks George Athens/Greece

Thanks for your answer. I have found NTSC video to PAL video or PAL-RF converters for Playstations, for less than $10each. Unfortunatelly, they do not support RF input, but only Composite input. I am not sure, but I suspect that I might be able to hack the PS/PS2 connector and replace it with a standard female RCA connector, and use it as the NTSC input port. I had found quite a long time ago, a generic device, that was used for the conversions, for far less than E100 (~$100), but I had no need for it at the time. My problem is that I have some micros, like the Ti99/4a or Commodore MAX, that use NTSC only standard output and I have is RF. Using a custom cable, I could bypass the Ti99/4a modulator, and use the composite video (in NTSC format) as the modulator is an external device. But for the USA version of the ZX80, I need to hack the motherboard, to get the video signal, unmodulated. And I do not want to alter or modify a "museum" item. I also do not want to use 3 different TV sets. It's very silly to do so. I have a SONY VCR that can playback NTSC video tapes, but it's not capable of translating the NTSC to PAL, and output it on PAL TVs. I know that there is professional equipment, and it's very complicated to convert the SECAM to PAL, as well as the NTSC to PAL. But I recall a small do-it-yourself kit (From Vellerman?) many many years ago that was supporting this function costing only a few Euros.

That won't work for more than one signal, since there isn't a common reference. Also, EIA-232 levels could damage EIA-422 devices.

On Thu, 5 Sep 2002, Tony Duell wrote: Maybe the confusion occurs because one of the most common RS-422 receivers is the 26LS32C which does have a +- 15V input range (+- 25V abs max) Peter Wallace Mesa Electronics

A non-text attachment was scrubbed... Name: not available Type: text Size: 1168 bytes Desc: not available Url : http://www.classiccmp.org/pipermail/cctalk/attachments/20020904/eb629c42/at…