daver2
10k Member
Hi Marty,
There seems to be a lot to take on board here...
T5 - if it is missing that is not good news!
There is a very good write-up of the TIG in KB11-A_Maint.pdf Page 204 of 214 Section 7.8.8 Fig 7-16. This diagram shows the phase relationships of the clocks to one another (simplified) and the text goes in to more detail.
To my knowledge - T1 through T5 should be there all the time - but there may be exceptions to that rule depending on the type of memory you have fitted???
The information regarding R139 is interesting. Was it a broken resistor or did it look good - but was open circuit?
There should be no difference with the TIG running with the XTAL oscillator or the R/C oscillator - other than the frequency of course. The two oscillators 'come together' at E32 pin 8 (74S64) and that is before the ring counter and logic that forms the timing generator. There is a possibility (with the R/C oscillator being a lower frequency) of a leaky capacitor, low gain transistor etc. affecting things. There seems to be a lot of discrete logic on this card - so I would look at that rather then the digital logic if you get discrepancies when you switch from the XTAL to the R/C oscillator.
The LOAD ADDRESS microcode goes from 170/167 -> 270 -> 230 -> 170 [REPEAT] so both 270 followed by 230 on a LOAD ADDRESS should occur.
EPROMS will work down to DC levels - so you can run an EPROM at any speed.
Did you 'bottom' the EXAMINE issue that was repeatable when the machine got warm/hot - or are you still working on that? I am note sure (from reading your posts) whether something you have done in the meantime has fixed that issue. If not, we still need to 'nail it down' (or is this what has lead you to the TIG?).
If you suspect a 'memory' problem - an 'out of the box thought' is to remove all the memory from the machine, set the switches up for a BRANCH instruction back to the same address and 'execute' the switch register...The switch register 'lives' at 777570. This is not a very 'interesting' program - but it will 'prove' a lot about the microcode and the CPU architecture (especially if you have your KM11 card up and running).
There are a number of issues for ROM. You have already identified EPROM devices and diode matrices. You could use diodes and DIP switches as well (so you can change the simple program on the fly). I used a 10x10 matrix plug-board many years ago. You could get shorting plugs and diode plugs. I used the shorting plug variant to make up things like RS232 testers and the diode plugs to make up ROM. Not sure I have seen any of these for many years though (they were used a lot in analogue synthesisers if I remember correctly)... I will have a hunt on the internet.
Remind me - does your BOOTSTRAP card work reliably with the console emulator in ROM? If so - do you have any spare sockets for ROM on this card? If you do - could you add some test program(s) to that?
If you did want to add a ROM card - are you thinking UNIBUS, MUD, FASTBUS or SPC? I could have a look at what you would have to wire up if I knew what your thoughts were. I am thinking of prettying up some SPC cards in the future for my own use - so quite happy to look at the SPC protocol.
Dave
There seems to be a lot to take on board here...
T5 - if it is missing that is not good news!
There is a very good write-up of the TIG in KB11-A_Maint.pdf Page 204 of 214 Section 7.8.8 Fig 7-16. This diagram shows the phase relationships of the clocks to one another (simplified) and the text goes in to more detail.
To my knowledge - T1 through T5 should be there all the time - but there may be exceptions to that rule depending on the type of memory you have fitted???
The information regarding R139 is interesting. Was it a broken resistor or did it look good - but was open circuit?
There should be no difference with the TIG running with the XTAL oscillator or the R/C oscillator - other than the frequency of course. The two oscillators 'come together' at E32 pin 8 (74S64) and that is before the ring counter and logic that forms the timing generator. There is a possibility (with the R/C oscillator being a lower frequency) of a leaky capacitor, low gain transistor etc. affecting things. There seems to be a lot of discrete logic on this card - so I would look at that rather then the digital logic if you get discrepancies when you switch from the XTAL to the R/C oscillator.
The LOAD ADDRESS microcode goes from 170/167 -> 270 -> 230 -> 170 [REPEAT] so both 270 followed by 230 on a LOAD ADDRESS should occur.
EPROMS will work down to DC levels - so you can run an EPROM at any speed.
Did you 'bottom' the EXAMINE issue that was repeatable when the machine got warm/hot - or are you still working on that? I am note sure (from reading your posts) whether something you have done in the meantime has fixed that issue. If not, we still need to 'nail it down' (or is this what has lead you to the TIG?).
If you suspect a 'memory' problem - an 'out of the box thought' is to remove all the memory from the machine, set the switches up for a BRANCH instruction back to the same address and 'execute' the switch register...The switch register 'lives' at 777570. This is not a very 'interesting' program - but it will 'prove' a lot about the microcode and the CPU architecture (especially if you have your KM11 card up and running).
There are a number of issues for ROM. You have already identified EPROM devices and diode matrices. You could use diodes and DIP switches as well (so you can change the simple program on the fly). I used a 10x10 matrix plug-board many years ago. You could get shorting plugs and diode plugs. I used the shorting plug variant to make up things like RS232 testers and the diode plugs to make up ROM. Not sure I have seen any of these for many years though (they were used a lot in analogue synthesisers if I remember correctly)... I will have a hunt on the internet.
Remind me - does your BOOTSTRAP card work reliably with the console emulator in ROM? If so - do you have any spare sockets for ROM on this card? If you do - could you add some test program(s) to that?
If you did want to add a ROM card - are you thinking UNIBUS, MUD, FASTBUS or SPC? I could have a look at what you would have to wire up if I knew what your thoughts were. I am thinking of prettying up some SPC cards in the future for my own use - so quite happy to look at the SPC protocol.
Dave
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