[2018-08-26 20:00:17 CEST] * rune joined [2018-08-26 20:00:58 CEST] * heinz joined [2018-08-26 20:01:06 CEST] hello dave [2018-08-26 20:01:21 CEST] Hello Heinz [2018-08-26 20:01:29 CEST] how are you? [2018-08-26 20:01:43 CEST] Im good thanks. Did I tell you I was going to retire? [2018-08-26 20:02:02 CEST] yes, you have mentoned it. [2018-08-26 20:02:07 CEST] soon? [2018-08-26 20:02:14 CEST] mentioned [2018-08-26 20:02:28 CEST] Well my boos has offered an additional 10K to wait for a year and train a replacement [2018-08-26 20:02:40 CEST] So I guess Im not retiring yet. [2018-08-26 20:02:55 CEST] But after december I only go into the office 2 days a week [2018-08-26 20:02:59 CEST] sounds good. [2018-08-26 20:03:03 CEST] It does [2018-08-26 20:03:17 CEST] More time for important things in life [2018-08-26 20:03:28 CEST] well decision [2018-08-26 20:03:53 CEST] some news about brexit? [2018-08-26 20:04:27 CEST] Its crazy, everyone is saying something wont work after Brexit. yesterday, it was horse racing [2018-08-26 20:05:07 CEST] What they, and the Eurocrats in Brussels dont remember is that Europe sells a lot to the UK as well as the other way [2018-08-26 20:05:24 CEST] what could go wrong after brexit? [2018-08-26 20:05:30 CEST] Barnier couldnt negotiate his way out of a wet paper bag [2018-08-26 20:05:58 CEST] Brussels sulks and hurts everyone just because they didnt get what they wanted [2018-08-26 20:06:11 CEST] UK will start trading with the rest of the world [2018-08-26 20:06:40 CEST] I heard VAG sells 25% of the cars they make to the UK [2018-08-26 20:06:52 CEST] If that stops, workers in germany will suffer [2018-08-26 20:07:17 CEST] same for BMW, FIAT, PEUGEOT, RENAULT and the rest [2018-08-26 20:07:33 CEST] also wine exporters [2018-08-26 20:07:54 CEST] The world needs to give and take, but Brussels justs wants to take [2018-08-26 20:08:18 CEST] is there a strong agricultural production in uk? [2018-08-26 20:08:32 CEST] what kind of? [2018-08-26 20:08:41 CEST] Yes, we are self sufficient. [2018-08-26 20:08:54 CEST] Livestock, cows, sheep, pigs [2018-08-26 20:09:04 CEST] no dutch tomatoes? [2018-08-26 20:09:14 CEST] Cerial, wheat, barley [2018-08-26 20:09:37 CEST] We do grow tomatoes, [2018-08-26 20:09:44 CEST] No german bananas though [2018-08-26 20:09:57 CEST] ;-) [2018-08-26 20:10:23 CEST] It may be hard at the start but things will sort themselves out [2018-08-26 20:10:28 CEST] Here is my plan [2018-08-26 20:10:43 CEST] Keep the border between Eire and Northern Ireland open [2018-08-26 20:11:00 CEST] Goods from Europe from Eire to NI to UK [2018-08-26 20:11:18 CEST] We make a fortune and the French lose out :) [2018-08-26 20:11:26 CEST] in germany we have a proverb: the soup will not be eaten as hot as it was cokked. [2018-08-26 20:11:33 CEST] cooked. [2018-08-26 20:11:57 CEST] yep, everyone wants to scare the ordinary people [2018-08-26 20:12:21 CEST] Brexit and non-brexit have their own agendas [2018-08-26 20:12:23 CEST] i wish you the best. [2018-08-26 20:12:34 CEST] and me. [2018-08-26 20:12:35 CEST] Thanks, I'll still talk to you afterwards [2018-08-26 20:12:53 CEST] some news about the zeddy? [2018-08-26 20:13:03 CEST] Yes, long story - are you ready? [2018-08-26 20:13:14 CEST] yes, i am. [2018-08-26 20:13:41 CEST] I opened a working Zeddy and hooked it to the small TV that works with the ZX NU, no display [2018-08-26 20:13:54 CEST] So I then tried it on a different TV and its OK [2018-08-26 20:14:22 CEST] So I went through ULA, ROM and 1-20 Z80 pins and captured the display oin the scope [2018-08-26 20:14:57 CEST] But I have mixed up on the ULA and need to recheck, but Im getting a collection of standard images [2018-08-26 20:15:23 CEST] Next I checked the Zeddy being repaired on the other TV and still no picture [2018-08-26 20:15:39 CEST] The ULA ROM and Z80 output looks good [2018-08-26 20:16:12 CEST] But the centre pin on TR1 is different. The working Zeddy has a wave pattern like a sine [2018-08-26 20:16:35 CEST] But the non-working Zeddy only has a constant high voltage [2018-08-26 20:17:07 CEST] I desoldered the TR1 and added a header. A new TR1 was put in and its still the same [2018-08-26 20:17:25 CEST] So I think I need to check around that PIN [2018-08-26 20:17:41 CEST] wait. [2018-08-26 20:17:53 CEST] Unfortunately the woking Zeddy has all chips soldered to the board [2018-08-26 20:17:56 CEST] OK, stopped [2018-08-26 20:18:23 CEST] the ulais generating the tv-signal. [2018-08-26 20:19:10 CEST] if it will produce a new tv-line it will send an nmi via pin 15 to the cpu. [2018-08-26 20:19:40 CEST] cpu pin 17. [2018-08-26 20:20:08 CEST] this signal goes also to the emitter of tr1. [2018-08-26 20:20:59 CEST] What is Pin Its a square wave on the working Zeddy 0-5V every 30 us? [2018-08-26 20:21:24 CEST] the signal at the base of tr1 comes from cpu-halt (output) [2018-08-26 20:22:03 CEST] what pin? [2018-08-26 20:22:40 CEST] 17 on working one. looked at image for non-working and its [2018-08-26 20:23:02 CEST] showing HI [2018-08-26 20:23:05 CEST] 17 at ula or cpu? [2018-08-26 20:23:09 CEST] ULA [2018-08-26 20:24:04 CEST] this pin is connected with the pin 19 (halt) at cpu. [2018-08-26 20:25:05 CEST] Pin 18 shows a square wave. Possible short somewhere in between? [2018-08-26 20:25:18 CEST] Sorry, hold on. [2018-08-26 20:26:01 CEST] I was right, ULA image starts at #40 for #58 is pin 19 [2018-08-26 20:26:57 CEST] I changed scales so I'll redo some tomorrow at the same scale as the ULA [2018-08-26 20:27:33 CEST] sorry, there seems to be a misprint in the scheme. [2018-08-26 20:27:52 CEST] do you have a scheme open? [2018-08-26 20:28:01 CEST] Yes [2018-08-26 20:28:24 CEST] what number is halt-pin at cpu? [2018-08-26 20:28:47 CEST] 19 [2018-08-26 20:28:48 CEST] in my scheme it is 19 [2018-08-26 20:29:14 CEST] I see Mreq is 19 too [2018-08-26 20:29:48 CEST] but if you look to the zilog data sheet halt is18. [2018-08-26 20:30:21 CEST] and nothing else is labelled as 18 [2018-08-26 20:30:48 CEST] right. 19 is mreq [2018-08-26 20:31:29 CEST] I've changed the scheme [2018-08-26 20:31:35 CEST] so, let us correct it in the scheme. [2018-08-26 20:32:01 CEST] back to the 30us spare wave. [2018-08-26 20:32:16 CEST] where did you detect it? [2018-08-26 20:32:36 CEST] On the centre pin of TR1 [2018-08-26 20:33:26 CEST] this is connected with pin 18 (halt) a cpu. [2018-08-26 20:34:03 CEST] could you find the square wave also at pin 18? [2018-08-26 20:35:11 CEST] I dont have an image for that one. I may have mixed it with 19 [2018-08-26 20:35:16 CEST] pin18 cpu [2018-08-26 20:35:19 CEST] On Z80 [2018-08-26 20:35:27 CEST] Yes, there is a gap. [2018-08-26 20:36:23 CEST] what time length/frequency? [2018-08-26 20:36:34 CEST] 10 us per div [2018-08-26 20:36:47 CEST] I'll email the TR signals [2018-08-26 20:38:04 CEST] Sent [2018-08-26 20:38:59 CEST] got it. [2018-08-26 20:39:36 CEST] time length is 4.5 units, means 45us. [2018-08-26 20:40:51 CEST] From peak to peak? I was only looking at trough [2018-08-26 20:41:02 CEST] Is 45 us OK? [2018-08-26 20:41:46 CEST] this means 22khz, a bit to fast. [2018-08-26 20:42:19 CEST] But that is on the working Zeddy [2018-08-26 20:42:26 CEST] did you pull the fine adjustment at your scope to the neutral position? [2018-08-26 20:42:44 CEST] No, is that the centre bit [2018-08-26 20:43:06 CEST] 16khz is the usual horizontal frequency at a tv set. [2018-08-26 20:43:21 CEST] I do have a signal generator, maybe I need to calibrate the scope [2018-08-26 20:43:43 CEST] I normally just turn things so I get a display :( [2018-08-26 20:43:45 CEST] but it is more or less the right frequency. [2018-08-26 20:44:07 CEST] Its probably needing calibrated [2018-08-26 20:44:52 CEST] during this time there take place the communication between ula and cpu in order to generate the next video line. [2018-08-26 20:45:40 CEST] back to the zeddy under repair. [2018-08-26 20:46:00 CEST] (expect there is no square wave signal. [2018-08-26 20:46:20 CEST] No, just a high voltage [2018-08-26 20:48:04 CEST] you should have a closer look into the assembly listing of the zx81 in order to understand how the communicatio,#the nmi and the halt work together. [2018-08-26 20:48:07 CEST] So I need to check for shorts around ULA 17 / Z80 18 [2018-08-26 20:48:26 CEST] do you have an assembly listing? [2018-08-26 20:48:38 CEST] I have rom disassemly book [2018-08-26 20:49:08 CEST] look there, how the tv picture is generateed. [2018-08-26 20:49:33 CEST] look for halt instruction and for nmi. [2018-08-26 20:50:06 CEST] OK, will do. I cant see the book in the case just now [2018-08-26 20:50:09 CEST] i will do the same, and next week we could discuss it. [2018-08-26 20:50:41 CEST] (#will send you an assembly by email. [2018-08-26 20:51:01 CEST] OK, thanks. I found 2 Speccy rom disassembly books [2018-08-26 20:51:13 CEST] next saturday i will be at wittenberg city for a speccy meeting. [2018-08-26 20:51:14 CEST] Shall we finish tonight [2018-08-26 20:51:25 CEST] Buy everything! [2018-08-26 20:51:30 CEST] yes, les us finnish. [2018-08-26 20:51:36 CEST] have a nice weeek. [2018-08-26 20:51:44 CEST] You too. Holiday tomorrow [2018-08-26 20:51:48 CEST] Bye [2018-08-26 20:51:51 CEST] bye. [2018-08-26 20:51:55 CEST] * heinz quit (EOT) [2018-08-26 20:51:57 CEST] * rune quit (Leaving)