test-drb December 2002

test-drb@ccmp.vtda.org

250 participants
519 discussions

by dwightk.elvey＠amd.com

>From: "Philip Pemberton" <philpem(a)dsl.pipex.com> > >Right - thanks for the suggestions Peter (and Dwight). I've printed off your >suggestions and I'll have a look through them tomorrow. The RAMs are >soldered in, though, so it'll be very difficult to swap them. Plus the holes >and pads on the board are *extremely* tiny. >Guess I was jumping to conclusions a bit... Just out of interest, has anyone >got a spare pair of 2732s and an EPROM burner capable of burning them? Just >in case it turns out the ROMs (TI branded - getting quite warm, same as the >CPU) are frazzled, too. Earliest I'll be able to get my sticky mitts on an >EPROM programmer and some 2732s will be around the 25th (think about it)... >*sigh* > >Thanks. >-- >Phil. >philpem(a)dsl.pipex.com >http://www.philpem.dsl.pipex.com/ > Hi Phil You didn't mention where you were? You might be right next door to someone that can help. Dwight >

21 years, 7 months

My first good find!!!

by Lee.Davison＠merlincommunications.com

Phil, > I don't suppose you have a copy of the Jupiter Ace > schematics, do you? http://www.home-micros.freeserve.co.uk/JupiterAce/JupiterAce.html Lee. ________________________________________________________________________ This e-mail has been scanned for all viruses by Star Internet. The service is powered by MessageLabs. For more information on a proactive anti-virus service working around the clock, around the globe, visit: http://www.star.net.uk ________________________________________________________________________

21 years, 7 months

Modern replica/implementation of a dumb terminal?

by Robert_Feldman＠jdedwards.com

I have heard of people using an HP LX palmtop (the 100LX/200LX have a fuller serial port implementation than does the 95LX) as a terminal for the type of tasks you mention. The 200LX runs MS-DOS 5.0 on an i80186, so you should be able to get a number of terminal emulation programs that will work on it. -----Original Message----- From: Ethan Dicks [mailto:erd_6502@yahoo.com] Sent: Tuesday, November 26, 2002 1:10 PM To: cctalk(a)classiccmp.org Subject: Modern replica/implementation of a dumb terminal? I was musing about the state of VT100s and other dumb terminals and had a few ideas zing by... <snip> I have used my Palm Pilot as a portable terminal for reconfiguring Cisco routers (VT100 app and a travel cable and the appropriate RS-232 dongles). My boss at the time flipped when he saw me do it (everybody else dragged a laptop into the server room). There are just times when I'd like a laptop-sized-or-smaller ANSI terminal. I can forego double-high/double-wide chars, inverse video and the like for simplicity's sake (hardly ever used them in an app except at the South Pole), but it should be complex enough to run a screen editor (vi or emacs) and/or basic curses apps (Rogue/Larn/NetHack and the like). One place I thought BIOS replacement might be handy was in a sub-486 laptop.... just pull it out, plug it in and *voila*, it's a dumb terminal weighing a few lbs. Yes, it's possible to drop an OS on a floppy and add Kermit (I've already done that with a dual-720K- floppy Zenith 8088 portabie). I'm thinking of a dedicated "instant- on" experience. I also have some "Net Stations" with a 5"x5" 486 motherboard stuffed under a PC keyboard (with 4 30-pin SIMM sockets, IDE, serial, video, and NE2000 network built-in). They don't run off batteries, but neither do they have an intergral screen. I've also tried to think of ways to adapt a Palm Pilot with a permanent keyboard, but I'm not sure there's a way to do it with only one serial port (terminals typically have at least two, even if one is dedicated to servicing the keyboard and somewhat "invisible" to normal operation. The final angle I've worked on is to recycle the main board in a VT220 (being somewhat physically small), but I don't have schematics and I don't know what signals go over the ribbon cable to the PSU/ Analog board under the CRT. So has anyone else wrestled with how to cobble up a portable VT-100? Anyone get any further? -ethan __________________________________________________ Do you Yahoo!? Yahoo! Mail Plus - Powerful. Affordable. Sign up now. http://mailplus.yahoo.com

21 years, 7 months

BIG problem with my Jupiter Ace

by philpem＠dsl.pipex.com

Hi all, I've just opened up my Jupiter Ace and I think the problem I'm having with it is far more severe than a blown CPU. It looks like while I was testing it this morning the PSU was accidentally powered up, the +12(unreg) connection made contact with the barrel of the power jack (-ve) and the PSU's -ve line made contact with one of the first five expansion bus pins on the topside of the board. The CPU was getting very hot - I've since swapped the original NEC D780C (1982 datecode) with a Sharp LH0080 Z80-A-CPU IC. The replacement is also getting hot (takes about a minute for either of them to hit 50deg C). Output >from the 7805 is 5.04V steady according to my Fluke 25 DMM. Video is being output and my TV can lock onto it, but the output is total garbage, no difference if I remove the CPU and ROMs or have them installed. The garbage is always the same, too, in case it matters. The replacement CPU is known-good - it came out of a working Toshiba HX-10 MSX. How should I proceed with this repair? I've got a Fluke 25 DMM and a Tek 466 storage scope at my disposal. Also, the schematics are almost unreadable. I got them from home-micros.freeserve.co.uk. Anyone got a better copy? Thanks. -- Phil. philpem(a)dsl.pipex.com http://www.philpem.dsl.pipex.com/

21 years, 7 months

BIG problem with my Jupiter Ace

by pete＠dunnington.u-net.com

On Dec 5, 23:15, Philip Pemberton wrote: > Right - thanks for the suggestions Peter (and Dwight). I've printed off your > suggestions and I'll have a look through them tomorrow. Dwight's suggestion about checking power etc is the obvious first thing -- I should have mentioned that. > Just out of interest, has anyone > got a spare pair of 2732s and an EPROM burner capable of burning them? Yes, to both. -- Pete Peter Turnbull Network Manager University of York

21 years, 7 months

BIG problem with my Jupiter Ace

by pete＠dunnington.u-net.com

On Dec 5, 18:08, Philip Pemberton wrote: > Hi all, > I've just opened up my Jupiter Ace and I think the problem I'm having > with it is far more severe than a blown CPU. It looks like while I was > testing it this morning the PSU was accidentally powered up, the +12(unreg) > connection made contact with the barrel of the power jack (-ve) and the > PSU's -ve line made contact with one of the first five expansion bus pins on > the topside of the board. > The CPU was getting very hot - I've since swapped the original NEC D780C > (1982 datecode) with a Sharp LH0080 Z80-A-CPU IC. The replacement is also > getting hot (takes about a minute for either of them to hit 50deg C). Output > from the 7805 is 5.04V steady according to my Fluke 25 DMM. Video is being > output and my TV can lock onto it, but the output is total garbage, no > difference if I remove the CPU and ROMs or have them installed. The garbage > is always the same, too, in case it matters. The replacement CPU is > known-good - it came out of a working Toshiba HX-10 MSX. > How should I proceed with this repair? I've got a Fluke 25 DMM and a Tek > 466 storage scope at my disposal. It would be worth looking to see if signals look consistent (ie outputs of gates behave in the way you'd expect from what you see happening on the inputs). If you're thinking of replacing every chip at once, or one-by-one, I'd advise against it. You won't be able to tell what's really wrong, and random swapping might just destroy an otherwise perfectly good IC. The 74LS166 is a serial-out shift register, and I expect that's what generates the video stream. Since you say you always get a good consistent picture, with characters (even if they're junk) or some cosistent pattern, the shifter and video timing is working. That's probably where most of your 393's are, too (they're dual 4-bit counters). Am I right in thinking the character set is soft-loaded from the ROM? ie, not in a character generator ROM? Then you wouldn't expect to get recognisable characters unless the CPU can run, and the ROM is OK. Try swapping the memory chips around. If that gives different (but self-consistent) video, at least some of it is working. If it makes no difference, either it's *all* fried or the buffers have gone west. Other obvious things to check are the CPU clock and /M1 lines. The Z80 clock needs to be pulled high, your scope should be able to show if the clock is a nice square wave that goes up to almost 5V (minimum acceptable is about 4.5V, IIRC). The /M1 line goes low once for each instruction fetch; it should be pulsing. The data and address lines should be pulsing. If the CPU is free-running becasue it can't read instructons, it might be executing NOPs or RSTs or just some random instruction, depending on whether the data bus is stuck all-high, all-low, or at some random value. One possible cause of CPU and SRAM getting hot is if the data bus which they're trying to drive is stuck with an active signal. See if you can isolate the bus, and if the CPU or video behaves differently. I'm just giving general advice here, as I've not used an Ace in decades, and have no idea what the circuit looks like :-) -- Pete Peter Turnbull Network Manager University of York

21 years, 7 months

UK electronic scrap prices.

by rigdonj＠cfl.rr.com

At 04:16 PM 12/5/02 -0000, Lee wrote: > >I know we've been through this before but does anyone >have a handle on the going rate for scrap PCBs in the >UK? > >The reason - I've been made aware of a quantity of now >obsolete microprocessor equipment but I'm bidding against >the scrap man. Who knows, he may be charging for the >removal but I'd hate to lose this to him. > Prices vary widely depending on how much gold is on the cards but prices seem to run from just about nothing to as much as $4/lb here in the US. Even at the high end, that's about $4 per average sized board which is pretty cheap for a usefull board IMO. Joe

21 years, 7 months

My first good find!!!

by dwightk.elvey＠amd.com

>To: cctalk(a)classiccmp.org > >Philip Pemberton wrote: >> I don't suppose you've got any spare 2114 RAMs as well, have you? I think >> the RAMs in my Ace may have died when I slipped with the PSU cable (oops). > >I have some 2114s if you have trouble finding a source. > >-- >John Honniball >coredump(a)gifford.co.uk > > Hi Before he starts ramdomly replacing parts, maybe it would be a good idea to trouble shoot it first. Just a suggestion Dwight

21 years, 7 months

BIG problem with my Jupiter Ace

by dwightk.elvey＠amd.com

>From: "Philip Pemberton" <philpem(a)dsl.pipex.com> > >Hi all, > I've just opened up my Jupiter Ace and I think the problem I'm having >with it is far more severe than a blown CPU. It looks like while I was >testing it this morning the PSU was accidentally powered up, the +12(unreg) >connection made contact with the barrel of the power jack (-ve) and the >PSU's -ve line made contact with one of the first five expansion bus pins on >the topside of the board. > The CPU was getting very hot - I've since swapped the original NEC D780C >(1982 datecode) with a Sharp LH0080 Z80-A-CPU IC. The replacement is also >getting hot (takes about a minute for either of them to hit 50deg C). Output >from the 7805 is 5.04V steady according to my Fluke 25 DMM. Video is being Hi 5.04 is an OK value. I wouldn't stick another Z80/780 in there until I knew that there wasn't something else connecting a bad voltage to the processor. You should first power up without the processor plugged in and measure the voltages on all of the pins. Once you've confirmed that there is no +12V or something where it shouldn't be, you can then look for drive contention issues. With the processor removed, find all of the CPU pins that control Writing and reading( I don't have a Z80 pinout handy ). Use pullups to put these into their off states ( no bus activity ). Now check the voltages on the data and address lines. Most TTL cause soft pullups to about 3.5V and any resistor pullup would bring the lines to +5V. These pullups are usually on the order of 5K or larger so you should be able to pull the line down, noticably with a 1K pull down. This will find most any of the issues with some other part that is hard driving against the bus lines. Once you are sure that there is nothing hard driving against the CPU, you could then plug it back in and look for other issues. Just plugging parts in at random would likely be a waste of time and may even do additional damage. Dwight >output and my TV can lock onto it, but the output is total garbage, no >difference if I remove the CPU and ROMs or have them installed. The garbage >is always the same, too, in case it matters. The replacement CPU is >known-good - it came out of a working Toshiba HX-10 MSX. > How should I proceed with this repair? I've got a Fluke 25 DMM and a Tek >466 storage scope at my disposal. Also, the schematics are almost >unreadable. I got them from home-micros.freeserve.co.uk. Anyone got a better >copy? > >Thanks. >-- >Phil. >philpem(a)dsl.pipex.com >http://www.philpem.dsl.pipex.com/ > >

21 years, 7 months

UK electronic scrap prices.

by Antonio.Carlini＠riverstonenet.com

>The reason - I've been made aware of a quantity of now >obsolete microprocessor equipment but I'm bidding against >the scrap man. Who knows, he may be charging for the >removal but I'd hate to lose this to him. How about ringing a couple up for "very rough quotes", explaining that you have N wotsits, each weighing M kg and see if you can get a ball-park range out of them. Alternatively, bid what it's worth to you - and if you lose, ask afterwards what the winning bid was. What sort of equipment is this? Old PCs or test gear? Antonio

21 years, 7 months

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test-drb December 2002