RE: TU58 problems

> > 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? First hit on Google for 'TU58 Emulator' (no quotes) for me was :

Re: TU58 problems

On 1/17/2016 1:40 PM, tony duell wrote: Incidentally, another reason I am not too keen on using an emulator is that I suspect there could well be logic faults in the CPU and if I am not careful I will just have a long list of unsolved problems, whch can be somewhat disheartenng... Yeah,

RE: TU58 problems

> > Yeah, but if the emulator doesn't work, > then you have another important clue. I _know_ there are problems on the TU58. It should detect the BOT and EOT markers and not let the tape run off the spool. It should never produce the waveform I am seeing at the output of the read comparator. No

RE: TU58 problems

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

Re: TU58 problems

>tony duell wrote: While the TU-58 tape will not have an RT-11 file structure, you can at least read each raw block and display the contents: Actually I believe the VAX11/730 console tape is an RT11 file system (for all there is no PDP11 involved). On a VAX, there is an application (named

RE: TU58 problems

> > On a VAX, there is an application (named EXCHANGE if I remember > correctly) which reads and writes the first partition of any RT-11 disk Err, yes... This implies I have a working VAX. Until I repair ths TU58 and get it to load the CPU microcode, I don't. Sure... > If you have a PDP-11

Re: TU58 problems

On 1/16/2016 12:26 PM, tony duell wrote: 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! And you don't want to use a TU58 emulator? (Or

Re: TU58 problems

>tony duell wrote: Similarly, it could be a useful diagnostic tool to connect the real TU58 hardware to a known-working (presumably slightly more modern) machine to see if it's willing to work that way. Yes. Does such a program exist? Something that will let me send commands to the TU58 and

Re: TU58 problems

On 1/16/16 12:44 PM, tony duell wrote: 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 This might not be what you want, but I boot my 11/730 from a tu58 emulator running on a linux box. I used a little

RE: TU58 problems

> 800 BPI (NRZI) only has transitions on a data track when As I understand it the TU58 is not NRZI. According to the manual (and I see this sometimes) a 'bit cell' starts with a +ve magnetic flux transition (OK, that is meaningless, it really means there is a +ve edge at the output of the read

RE: TU58 problems

> > I can certainly understand that. But a TU58 emulator could be a useful > diagnostic tool. Personally, I would try to get it working from the Agreed. But a diagnostic tool is only useful if you can trust it. I suspect that if I tried to set up a TU58 emulator I would have problems due to

RE: TU58 problems

> > 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 > > > This might not be what you want, but I boot my 11/730 from a tu58 > emulator running on a linux box. I used a little ttl<->rs232 converter >

Re: TU58 problems

Hello, well, if you see square waves, probably the read path analog circuit could auto-oscillate. This could be because of poorly filtered supply (bad electrolytic capacitors), or possibly some component in the feedback that's not soldered well. I should have a schematic around, I could give a

Re: TU58 problems

On Jan 16, 2016, at 12:15, tony duell wrote: > I had considered that, or one of the TU58 emulators that use SD cards or > similar but (a) I am trying to restore this VAX, not make a machine that runs > VAX software and is not original and (b) I do have this moral

Re: TU58 problems

On 01/16/2016 11:44 AM, tony duell wrote: 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. No, not correct for 800 BPI (NRZI). That is somewhat how

RE: TU58 problems

> > > > 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! > > > > And you don't want to use a TU58 emulator? (Or you enjoy

Re: TU58 problems

On Sat, 1/16/16, tony duell wrote: > 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 >

Re: TU58 problems

>>> 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! >> And you don't want to use a TU58 emulator? > No, I don't want to use a TU58 emulator for the same reason that I am > restoring this VAX and

Re: TU58 problems

On 01/16/2016 02:31 PM, tony duell wrote: 800 BPI (NRZI) only has transitions on a data track when As I understand it the TU58 is not NRZI. WHOOPS! I Somehow read that as one of the 1/2 9-track tape drives! Jon

RE: TU58 problems

> Moral objections have nothing to do with getting as many tools on a > problem as you can. True. But if you don't have said tools set up and working, you may find (or at least I will find) that when somethng doesn't work you are not sure if the problem is a genuine fault or

RE: TU58 problems

> While the TU-58 tape will not have an RT-11 file > structure, you can at least read each raw block > and display the contents: Actually I believe the VAX11/730 console tape is an RT11 file system (for all there is no PDP11 involved). -tony

RE: TU58 problems

> If it were me, I'd start by setting up some tests to determine what exactly > the protocol analyzer is doing. If it really is dropping 0 bytes, then I'd Well, I see 2 ways forward, in that I have found 2 things that look odd... One is to investigate the serial link between the VAX console