test-drb

test-drb@ccmp.vtda.org

101090 discussions

by jwest＠classiccmp.org

Someone would like to move out a Micro LSI-11 in a BA23 pedestal cabinet. Location is Northwest Ohio. Email me off-list if interested. J

10 years, 3 months

Preferred way of substituting TFT for CRT Monitor?

by Martin.Hepperle＠dlr.de

> What is the exact model number of the video card? > > I am assuming it's an HP98204 of some flavour. The HP98204A uses (US, RS170) TV rates and > can be connected to any composite monitor that expects that. A lot of TVs (rather than monitors) > in Europe can accept that and have composite inputs still, perhaps on a SCART socket. > > However the more normal video card in the 9000/217 (aka HP9817) is the HP98204B. This does > have a composite output but at rather odd rates. There was a specal 'HP' (actually a Samsung > chassis, and it shows!) monitor for this. I thinkl finding somethng that will lock to the video output > of that card is going to be 'interesting' > > Do you have the original HP monitor? If so, what model is it? > > -tony Hi Tony, indeed this machine has a 98204B video board (intended to work with a 35721 monitor, which I don't have). I have not yet found the specs for its composite signal. I find many $20 converters/scalers for composite to VGA on amazon or ebay but I am not sure whether such a thing would work for me. Obviously they seem to work for many computer games (SNES, Nintendo) and for some hobby computers like C64, Amiga etc. (e.g. "RCA Composite AV S-Video to VGA Converter Box"). Next I see $50 devices like "Mini Composite RCA CVBS AV To HDMI Converter (Input: AV; Output: HDMI)" which may also be an option, but only seem to scale to a fixed HDMI resolution, which may be unsuitable for the HP-resolution of 512x400 (or 512x390?). Finally I see $200 converters/scalers which are a bit expensive just for trying to see whether they work (e.g. "Atlona AT-AVS100 Composite/S-Video to Component/VGA Scaler"). I have also contacted Jon from the HP-Museum to see what their solution is. Regards, Martin

10 years, 3 months

DEC Rainbow PC100-A

by shadoooo＠gmail.com

> So if all LEDs remain on, that most likely means the CPU is not able to execute instructions at all. > It might mean a busted CPU, busted ROM or CPU bus, or missing power or clock. Yes, that's exactly my feeling... so a schematic would be very good to try to diagnose an evident problem as missing signals, etc, knowing what they should be from the circuit diagram. I will try to check something easy at first, knowing the pinout of the microprocessors... but after that I suspect it will be harder. Andrea

10 years, 3 months

cctalk Digest, Vol 19, Issue 18

by shadoooo＠gmail.com

10 years, 3 months

Non-baking cure for sticky shed? (being serious for a moment)

by dave.g4ugm＠gmail.com

I know that tapes have different coatings, so some are ferrous and other chrome based, but what about the backing and "glue" that holds the two together? Dave G4UGM > -----Original Message----- > From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Chuck > Guzis > Sent: 17 January 2016 23:41 > To: General Discussion: On-Topic and Off-Topic Posts > <cctalk at classiccmp.org> > Subject: Re: Non-baking cure for sticky shed? > > On 01/17/2016 02:00 PM, ben wrote: > > > > > Why not just grab a few 8 tracks from the truck out back. > > > > > ...Or fill those old QIC cartridges with some old acetate-base 1/4" > open-reel audio tape? After all, it's all the same... > > --Chuck

10 years, 3 months

DEC Rainbow PC100-A

by shadoooo＠gmail.com

Hello, I recently took a DEC Rainbow PC100-A. It has been a huge house for a lot of spiders, who deposited eggs and dead insects all around. After full disassembling, cleaning and reassembling, I'm ready to try it! PSU seems to work well, power goes on with almost precise voltages, then all the test leds on the back will lit on... then nothing happens! No video, no sign of life. Clearly there's a problem at the very beginning of the boot phase, that could be caused by a lot of reasons. In the next days I will try to analyze possible causes of the problem with oscilloscope, in the meantime I'm searching a schematic, as board is very complex to follow trace-by-trace. On bitsavers I found a schematic of PC100B, but the main board is not the same as PC100A. Anybody has a schematic for PC100A? I suspect that ROMs could be damaged, anybody has a correct dump to verify the content of the EPROMS? Thanks Andrea

10 years, 3 months

My TU58 again

by ard＠p850ug1.demon.co.uk

I think I have had a most instructive day. I did what I should have done a lot earlier and connected a (cheap, built from a Velleman kit) DSO to the output of the read amplifier in my TU58. That's pin 6 of the CA3130 at location E28 if you are trying to follow along in the printset, The printset indicates a wobbly waveform there marked 5Vpp. My little DSO can display the peak-peak measurement of a waveform. I started by cleaning the heads and demagnetising them (with one of those mains-powered electrmomagnet things). Of course I unplugged the drive from the controller before doing that in case the induced voltage was enough to damage things. Remember I have removed the 8155 from the controller board and fitted a socket, I have used jumper wires there to start and stop the tape, change direction, etc without the 8085 part getting in the way. I have what appears to be a new TU58 cartridge. With that in the drive I get a steady (and clean-looking) waveform of about 3.6Vpp. Low, compared to the value in the prints, but I suspect high enough to work. Then I tried my console tape. It goes all over the place. Sometimes 4V. Sometimes under 1V. And it is anything but a clean signal. There were times when it was just a little ripple. As I understand it there are no gaps in the formatting of a TU58. Certainly not ones that last for several seconds at normal tape speed. Worse than that, when I put the new cartrige back in the ampltude was significantly lower, around 2.7V. It came back when I cleaned the head again. My conclusion at this point is that my console tape is suffering from major dropouts and is shedding oxide. So now I need to get a good tape (maybe the new one I have), fix the standalone TU58 and dump the console tape image onto it. Or does anyone have any other ideas or comments? -tony

10 years, 3 months

TU58 problems

by bob＠jfcl.com

What's the SD card based TU58 emulator that a couple of people mentioned? Is that just a Raspberry PI with linux and the existing TU58 emulator software, or is there something more purpose built? Bob

10 years, 3 months

TU58 problems

by ard＠p850ug1.demon.co.uk

I am not sure this fits in with the current topics of this list on the grounds it involves real old hardware, but anyway.. I am currently trying to restore a VAX11/730. I got this about 20 years ago and dismantled it to get it home. For various reasons I never put it back together, I am doing that -- slowly -- now. It's the version in the half-height rack with an R80 at the bottom, then the 11/730 CPU box, and a TS05 on top. I know I am going to have problems with the storage devices, for the moment I am jsut trying to get the CPU running. I've remounted it in the rack, got all the ribbon cables in place, tested the PSU, etc. Minor PSU problems (leaky transistor) but now fine. Powering up gives the expected ROM> prompt on the terminal. Of course all you can do at that prompt is load the microcode from the TU58, so that is what I am trying to get working. And getting nowhere! Firstly the TU58 controller is not passing the self-test. I am pretty sure the 8155 RAM/IO chip is dead. I have removed this and fitted a DIP socket. The rollers were of course dead. I have made hubs and fitted an O-ring of a suitable size. This may not work correctly, but it does seem to move the tape. I have a couple of tape cartridges, the Console microocode tape, and amazingly the belt seems good in them. The motor does get the tape whizzing past the heads. I tried an 8155 borrowed from another device. The controller then passes the self-test (the LED comes on and stays on) but all I get is DD1: Read Error messages and the tape often runs off the spool (rethreading it is something I've got quite good at!). I tried a RS232 analyser between the TU58 and the VAX. Very odd. Either my RS232 anaylser drops 00 bytes or the TU58 sets short result packets. The meaningful bytes (response code, etc) are there, but things like the sequence number are not. Odd... With the 8155 removed, I can pull port pins (on the socket) high and low to start the motor, select drive, track, direction, etc. I've done that and put a LogicDart on the output of the comparator in the read amplifier. According to the manual, the tape is recorded at 800bpi and runs at 30ips. So I get that a bit should take around 41us. And a bit starts with a rising edge, the position of the falling edge (recorded at 1/4 or 3/4 of the bit time) determines whether it's a 0 or 1. Well, sometimes that's what I see on the LogicDart. Sometimes I see a 1:1 square wave with a period of 40-odd us. Does anyone have any sensible ideas as to what to try next. At the moment I have no idea if it's the tape, heads, roller or what.... -tony

10 years, 3 months

P112 CP/M computer kits still available

by dave＠661.org

FYI, I still have lots of P112 CP/M computer kits for sale. Please buy one or several. See http://661.org/p112/ -- David Griffith dave at 661.org A: Because it fouls the order in which people normally read text. Q: Why is top-posting such a bad thing? A: Top-posting. Q: What is the most annoying thing in e-mail?

10 years, 3 months

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