"chaz_heritage.WGC1RX"@XEROX.COM (06/12/89)
In his Thu, 1 Jun 89 14:56 N Roger Hunen writes: >If you have a NEC P2200 connected to your ST *without* modifica- tion, DISCONNECT it now.The 1 kOhm pull-up resistors on the Cen- tronics interface of the NEC will eventually kill the sound chip of your ST.< Has anyone out there actually had their ST damaged by using it with a P2200? Until Mr. Hunen posted his fix for the problem I didn't know it existed - I had to call NEC (UK) to get some driver software for my ST to dump Degas correctly on my new P2200, and they didn't mention any hardware compatibility problem at that time. I'd like to use a printer buffer on my system, to allow me to keep on working while printing Degas or CAD frames, which take forever. Would such a buffer provide the correct pull-ups? Or would it also be likely to damage the ST? Has anyone tried it? I don't really want to make up Mr. Hunen's fix box only to make it redundant afterwards by buying a printer buffer. Anyone got any clues? Regards, Chaz PS This problem seems to be related to the numerous problems and fixes associated with fitting an IBM-type 5.25" disc drive - one has to buffer a number of lines controlling the drive, which are also generated by the wretched sound chip. Is there no way of buffering the chip itself, and thus killing a number of birds with one stone? Anyone tried it, before I get my soldering iron out?
hcj@lzaz.ATT.COM (HC Johnson) (06/13/89)
In article <890612-090337-12728@Xerox>, "chaz_heritage.WGC1RX"@XEROX.COM writes: > In his Thu, 1 Jun 89 14:56 N Roger Hunen writes: > > >If you have a NEC P2200 connected to your ST *without* modifica- > tion, DISCONNECT it now.The 1 kOhm pull-up resistors on the Cen- > tronics interface of the NEC will eventually kill the sound chip > of your ST.< > > Has anyone out there actually had their ST damaged by using it with a > P2200? Until Mr. Hunen posted his fix for the problem I didn't know it > existed - I had to call NEC (UK) to get some driver software for my ST to > dump Degas correctly on my new P2200, and they didn't mention any hardware > compatibility problem at that time. > > I'd like to use a printer buffer on my system, to allow me to keep on > working while printing Degas or CAD frames, which take forever. Would such > a buffer provide the correct pull-ups? Or would it also be likely to damage > the ST? Has anyone tried it? I don't really want to make up Mr. Hunen's fix > box only to make it redundant afterwards by buying a printer buffer. > > Anyone got any clues? What is being overlooked is that the specs on chips are 'guaranteed' minimums. Thus while the sound chip guarantees to sink 1.6 ma, it doen not mean that it wont do better than that. Also, from the various specs posted, it would appear that not all lines may have 1000 ohm pull ups on different devices. If only a couple (control) lines need 5 ma, it may not be noticed. Also, as was previously pointed out, the first order effect of a 1000 ohm pullup is that the ON signal will not pull to 0.3 volts, but instead to a higher level, which may or may not be interpreted correctly. Marginal performance would be the likely result. It is more likely that a 1000 ohm device will fail to work before it could damage the ST. On Bus repeaters and electronic printer switches: If they have 1000 ohm terminators, same problem. The one I have works on long leads so I'd say its designed to use lower currents. Howard C. Johnson ATT Bell Labs att!lzaz!hcj hcj@lzaz.att.com
schuster@dasys1.UUCP (Michael Schuster) (06/19/89)
In article <890612-090337-12728@Xerox> "chaz_heritage.WGC1RX"@XEROX.COM writes: > >Has anyone out there actually had their ST damaged by using it with a >P2200? Until Mr. Hunen posted his fix for the problem I didn't know it >existed - I had to call NEC (UK) to get some driver software for my ST to >dump Degas correctly on my new P2200, and they didn't mention any hardware >compatibility problem at that time. Once again, leave it to Atari to provide "fake compatibility". They give you industry-standard connectors and pinouts, but incredibly bizarre signal handling! The original TOS would not handshake the RS232 lines properly. The printer port is incompatible with a printer that NO OTHER COMPUTER has a problem with. I could go on ..... I've seen THREE locals dump the P2200 because of constant random errors in graphics printouts (e.g. PageStream/Pub Partner). I experienced them too, but added a printer buffer. That solved the problem. To answer your question --- I don't know if this is related, but I was having big compatibility problems exchanging both 3.5" and 5.25" IBM-formatted floppies between my Atari and my PC. Every time the ST wrote something to the inner tracks, the PC would think the disk was damaged. Curiously enough, this problem VANISHED when I connected a MicroFazer between my P2200 and my Atari. Now, since the ST is the only computer in existence that has an intimate link between an unbuffered parallel port and an several unbuffered signals going to the floppies ....Coincidence? -- l\ /l' _ Mike Schuster ...!dasys1!schuster l \/ lll/(_ Big Electric Cat schuster@dasys1.UUCP CIS:70346,1745 l lll\(_ New York, NY USA BIX,DELPHI,GEnie:MSCHUSTER