[cctalk] Tracking Down a RAM Issue in a VT100 (how does the 2114 chip work?)
I have a non-functioning VT100. I think it is failing in the POST during the RAM check. I don't know for sure because I can't get it to light up the LEDs on the keyboard, however I used my logic analyser (a HP1630G) to see what values were written to the UART to send to the keyboard and I see it sends the values FF then 1, 2, 3, 4 and finally 5. The last value corresponds to the RAM test so I am fairly confident the RAM test is what is failing. I have disassembled the VT100 ROM and if I have understood it correctly it zeroes out the RAM (high address to low) and then for each address (low address to high) it tries first to read back the zero and then writes 0xAA to the location and tries to read that back. I am also confident the 8080 is working OK because I was able to capture an address trace on the ROM that showed it executing the program as per the disassembled ROM. My problem is getting the logic analyser reliably to tell me how each RAM chip is being addressed and what data is being read or written. I am seeing strange values for the addresses (sometimes) and I am not sure I have setup the logic analyser correctly. I have read the datasheet for the 2114 chip and I am not entirely clear that I have understood it correctly. Here is how I have set it up: Trigger on the -ve edge of Chip Select (pin 8) Capture A9-A0 as the address Capture WE as an indication of Read or Write The timing diagrams show the write cycle where the WE signal and CE signal seem to transition at the same time and the data may be only valid a bit later then the CS -ve edge. But this may just be me not knowing how to read the datasheet. Using the +ve edge of CS seems no better. Is there something I am missing about how to analyse how the RAM chips are being used? Thanks Rob
[cctalk] Re: Concorde cabin display technology?
I did find a reference on the UK Concorde Heritage site from a Guy who mentioned that He had been involved with rehabilitating The Marilake in their aircraft, although it was 2011. I may try to ping Him and see what he knows. Mark -Original Message- From: Bob Rosenbloom via cctalk Sent: Saturday, September 16, 2023 11:12 PM To: cctalk@classiccmp.org Cc: Bob Rosenbloom Subject: [cctalk] Re: Concorde cabin display technology?
[cctalk] Re: Concorde cabin display technology?
Hi Bob, Yes, I've found no shortage of statements on the web saying they Were LCD or Plasma, just haven't found anything definitive. ` The early plasma displays, like the Compaq III portable, Grid Case And others were definitely orange-red. For a while it was thought that Plasma displays were going to take over the world, which they did for a while. There was apparently a lot of work going on in color plasma displays in the 80's, but it seems unlikely that a suitable color plasma was available and rated for aircraft service by 1985. I found a NASA tech report concerning developing plasma displays for the Space Shuttle. The commercial color displays arrived in 1992, but they were developed with much higher res and color gamut than the Concorde use would have required. Given the time period, I wonder if there is anyone at modern Day Marilake that would still have the information. They did bid the proposed Updated Mach display for the return to flight planned upgrade, but that Never really happened. Called the "Rocket Project". There is a reference On an old (2005) edition of their web page. It does say that that version was LCD. You can see that here: https://web.archive.org/web/20050207053216/http://www.marilake.com/ Select "Products" then "Concorde Displays" Mark -Original Message- From: Bob Rosenbloom via cctalk Sent: Saturday, September 16, 2023 11:12 PM To: cctalk@classiccmp.org Cc: Bob Rosenbloom Subject: [cctalk] Re: Concorde cabin display technology? This link mentions the Marilake displays were LCD: https://www.airliners.net/forum/viewtopic.php?t=194031 Most plasma displays I've seen were more red or red/orange. The Marilake displays look too yellow. Could be a monochrome LCD with an EL backlight. Bob On 9/16/2023 9:55 PM, Mark Huffstutter via cctalk wrote: > Actually, it is a "Marilake" display, built by Marilake in the UK, > still in business. > From what I have been able to find, they were installed in British > Airways Concordes Around 1985, to replace a much less attractive 7 > segment LED display. The French Concordes apparently retained the earlier > LED type display. > > The other article is referring to a different display that replaced the > Marilakes. > Most of the references I have found indicate the Marilakes were Plasma > displays. > Nothing definitive, however. > > www.marilake.com/ > > Mark > > -Original Message- > From: ste...@malikoff.com steven--- via cctalk > Sent: Saturday, September 16, 2023 9:37 PM > To: General Discussion: On-Topic and Off-Topic Posts > > Cc: ste...@malikoff.com ste...@malikoff.com > Subject: [cctalk] Re: Concorde cabin display technology? > > > Andrew said >> Just found this article, and apparently the old displays were >> replaced with the new ones shortly after the grounding in 2000/2001. >> This would mean they are probably LCDs. >> >> http://www.concordesst.com/returntoflight/mods.html >> >> Also, here's a photo that very clearly shows the refresh: >> >> https://www.jetphotos.com/photo/7009833 > Interesting. Searching for 'Marrilite display' (I wonder what that is) turned > up this page, which mentions "There was a plasma display at the front of the > cabin showing the altitude, the air temperature and the current speed in both > miles per hour and Mach number." > https://www.heritageconcorde.com/concorde-cabin--passenger-experience -- Vintage computers and electronics www.dvq.com www.tekmuseum.com www.decmuseum.org
[cctalk] Re: Concorde cabin display technology?
On 9/16/23, Mark Huffstutter via cctalk wrote: > Actually, it is a "Marilake" display, built by Marilake in the UK, > still in > business. > From what I have been able to find, they were installed in British Airways > Concordes > Around 1985, to replace a much less attractive 7 segment LED display. The > French > Concordes apparently retained the earlier LED type display. > > The other article is referring to a different display that replaced the > Marilakes. > Most of the references I have found indicate the Marilakes were Plasma > displays. > Apparently they never actually installed newer displays despite the impression I got from the last article I linked. That makes a bit more sense. I'd think if they'd installed them in the early 2000s they would have used full-color displays. https://www.airliners.net/forum/viewtopic.php?t=319307 According to this thread, there was an early version of the Marilake display that was an LCD, but for various reasons it was rather flaky and they ended up replacing it with a plasma display, which is what is seen in most photos/videos. https://www.pprune.org/tech-log/423988-concorde-question-61.html
[cctalk] Re: Concorde cabin display technology?
This link mentions the Marilake displays were LCD: https://www.airliners.net/forum/viewtopic.php?t=194031 Most plasma displays I've seen were more red or red/orange. The Marilake displays look too yellow. Could be a monochrome LCD with an EL backlight. Bob On 9/16/2023 9:55 PM, Mark Huffstutter via cctalk wrote: Actually, it is a "Marilake" display, built by Marilake in the UK, still in business. From what I have been able to find, they were installed in British Airways Concordes Around 1985, to replace a much less attractive 7 segment LED display. The French Concordes apparently retained the earlier LED type display. The other article is referring to a different display that replaced the Marilakes. Most of the references I have found indicate the Marilakes were Plasma displays. Nothing definitive, however. www.marilake.com/ Mark -Original Message- From: ste...@malikoff.com steven--- via cctalk Sent: Saturday, September 16, 2023 9:37 PM To: General Discussion: On-Topic and Off-Topic Posts Cc: ste...@malikoff.com ste...@malikoff.com Subject: [cctalk] Re: Concorde cabin display technology? Andrew said Just found this article, and apparently the old displays were replaced with the new ones shortly after the grounding in 2000/2001. This would mean they are probably LCDs. http://www.concordesst.com/returntoflight/mods.html Also, here's a photo that very clearly shows the refresh: https://www.jetphotos.com/photo/7009833 Interesting. Searching for 'Marrilite display' (I wonder what that is) turned up this page, which mentions "There was a plasma display at the front of the cabin showing the altitude, the air temperature and the current speed in both miles per hour and Mach number." https://www.heritageconcorde.com/concorde-cabin--passenger-experience -- Vintage computers and electronics www.dvq.com www.tekmuseum.com www.decmuseum.org
