Michael J. Mahon wrote:
e p chandler wrote:On Nov 23, 7:25 am, "winston19842...@yahoo.com" <winston19842...@yahoo.com> wrote:On Nov 23, 5:39 am, e p chandler <e...@juno.com> wrote:On Nov 23, 2:47 am, A2Aviator <a2avia...@gmail.com> wrote:Epson still offers the C88+ - which the specifications list as having parallel and USB.The question begs, is it centronics or the other higher density connector. But it does support ESCP/2 protocol, which is downwardcompatible with ESC and that means the Harmony, Independence and Epson-APL drivers will work with it. I've used various Epson models over the years on A2's without any issues. You may not get color from any standard print drivers, but you can get color from Printshop, and from AppleWorks using ESC codes to turn it on the same way as the ImageWriter II/LQ....which is also another option for you, find an ImageWriter II, blast out the head with denatured alcohol and then put a bit if silicone spray in where the wires are passing through the front. WD-40 is *bad*. Those C-iToh ribbons are still pretty common.Okidata, Epson and C-iToh are basically it ribbon wise.See other message. Thanks for the idea to try the C88+. I happen to use one on my Vista system (as USB). Again, I'm amazed that it prints at all under Apple DOS and MS-DOS using the parallel port. There are other printers that will not print from Apple DOS or MS-DOS at all. They require a WIndows driver. IIRC I tried printing to an old Lexmark inkjet from "DOS" and got garbage.At least the EPSON has a character mode! Perhaps a different printer card would work? My Apple 2e has a clone of the old Apple Parallel card. I don't have a more modern parallel card on hand, like a Grappler. It could be that the handshaking is different.The old Apple Parallel card used very primitive handshaking. One line changed the addressing on the cards ROM to go from an endless loop to transmiting data. So some of the other signal lines could be missing,---- eNever overlook the obvious - printer cables. They can go bad, without any apparent damage. Have you a spare you've tried?Not between the Apple 2e and the printer. It's a ribbon cable that terminates in a male centronics. The cable plugs into a molex(?) connector on the board. The interface card and computer run just fine with 2 other printers. A Deskjet 500 and a Deskjet 310. The C88+ printer runs just fine when connected to a MS-DOS machine via a standard 25 pin D-sub to male centronics parallel printer cable. In fact I used the Deskjet 500 and the same cable on an XP machine as the primary printer a few years ago. If this printer is know to work with an Apple 2e using some other interface card, I'll try to get that interface card...It's hard to get much simpler than standard "Centronics" signalling, and all the Apple II parallel cards do it well. The Apple presents a character on the data lines and sends a STROBE pulse saying data's ready. The printer acknowledges with an ACK pulse and the Apple proceeds to the next character. (As you noted, the original Apple II parallel card has a very clever and economical way of sensing the ACK pulse. ;-) Fancier interfaces may also look at the BUSY/READY line and/or the PAPER ERR line, but they are only relevant to diagnosing problems, not to proper operation of the printer. Of course, "Centronics" came to be just a generic name for a whole family of "IBM PC printer" interfaces, some of which are quite exotic. But, in principle, they should all retain backward compatibility with the original "actual" Centronics interface.
I just realized a possible issue with a newer printer connected to an Apple II--the ACK pulse may be too short for the Apple to reliably sense it! The Apple interface card ROM essentialy polls the ACK line in the tight loop you mention--in fact, the lack of the usual data read followed by a conditional branch allows it to poll faster, and therefore tolerate shorter ACK pulses. However, an ACK pulse must be at least one loop period in length to be reliably sensed, so it may need stretching to interface with an Apple II. -michael NadaNet and AppleCrate II: parallel computing for Apple II computers! Home page: http://home.comcast.net/~mjmahon "The wastebasket is our most important design tool--and it's seriously underused."