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SD2PET & 8050

C

Caterman

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Joined
Jun 23, 2015
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Having a little bit of a strange problem.
I have a switch on my 8050 to select either device No. 8 or 9
When 8050 and SD2PET plugged in together even with 8050 switched off the SD2PET will not function.
Not even with 8050 hard selected as device 9 powered on or off.
The 8050 works perfectly with my two converted 1541 -> 2031LP's which I can switch to 8, 9 or 10.
The SD2PET works fine with my 2031LP clones!!
It's just the 8050 with SD2PET that is the problem.
Don't really want to transfer from SD2PET to 2031LP then on to 8050 after cable changing over.
What is going on?
 
Caterman said:
Having a little bit of a strange problem.
I have a switch on my 8050 to select either device No. 8 or 9
When 8050 and SD2PET plugged in together even with 8050 switched off the SD2PET will not function.
Not even with 8050 hard selected as device 9 powered on or off.
The 8050 works perfectly with my two converted 1541 -> 2031LP's which I can switch to 8, 9 or 10.
The SD2PET works fine with my 2031LP clones!!
It's just the 8050 with SD2PET that is the problem.
Don't really want to transfer from SD2PET to 2031LP then on to 8050 after cable changing over.
What is going on?
Click to expand...
The GPIB is a shared bus with effectively OR's data and if all is working, when the primary address is issued, only the one device with that hardware address should respond. If two devices respond together, and corrupt each other, that implies that something has gone wrong in their logic that encodes the address and they are responding when they should not, or responding to more than one address with a fault. If you set a device to say 9, play around with it to see if it also responds to 8, or if you set it as 8, check to see if it also responds to 9, as an experiment on both the SD2PET and the 8050.
 
Just can't get the 8050 to work with the SD2PET, has anyone got both to work at the same time!
8050 works perfectly when connected with a couple of 2031 drives in both ID8 and ID9 no problems, passes all performance tests, load saves no problem as do the 2031's
Does anyone have a way of having a permant change of the SD2PET ID from 8 to 9 and back again other than software!
 
Caterman said:
Just can't get the 8050 to work with the SD2PET, has anyone got both to work at the same time!
8050 works perfectly when connected with a couple of 2031 drives in both ID8 and ID9 no problems, passes all performance tests, load saves no problem as do the 2031's
Does anyone have a way of having a permant change of the SD2PET ID from 8 to 9 and back again other than software!
Click to expand...
So far it doesn't make sense as the bus can support multiple devices. Assuming that the 8050 and the SD2PET are actually only responding to two different device numbers only, there must be something interfering with one of the control or data lines when the two units are combined. It might be time to get out the scope and try to find out what is happening. I have used the SD2PET as device 8 in conjunction with an SFD1000 drive set as 9 and had no troubles.

I'd guess its a problem in the 8050. Perhaps one of the lines from the 8050 is sinking current, enough to pull it down when combined with the SD2PET, but not enough to affect your converted 2031LP's so they run ok with the 8050,
 
Compared P1 IEEE-488 connector pins to ground resistance values between 8050 and my 4022 Printer.
All are very similar values with the exception of Pin 9 which is IFC Interface Clear
On the printer it is open but on the 8050 it measures similar to other connected pins at 1.6k ohms
Interestingly the 8050 manual schematic does not show any connection for pin 9 on Schematic for PCB 8050001??
I have PCB 8050002 Pin 9 is tied to ground via R6 which measures 1.6k ohms although page 24 states should be 2.4k

I am lost about the bus being terminated properly I thought that the computer querried the bus and items respond on EOI pin 5
Never had an issue of terminating the IEEE-488 bus with all my other bits of kit.
 
Just to confirm I have tried the SD2PET first on Bus then 8050 and the other way round with SD2PET last
 
With the design of the SD2PET not having a pass through perhaps I am asking the impossible. The SD2PET may just not play nicely with 8050's
Nice to hear from others with SD2PET's and 8050's if they work togther!
 
It's one of the more modern ones. It works with everything I have including 4022 & 4022P & 2031 Clones?
 
It is easy to make a double adapter for the SD2PET and give it a pass through and as noted works fine with the SFD1001 or with a GPIB to serial printer adapter, it improves it too because the SD card is facing upward.

H

Thread 'PET IEEE-488 Double Adapter.'

I wanted to run my SD2PET and my SFD1001 drive from the PET, but had no way of plugging them on at the same time.

I considered how to make a double adapter, triple adapter etc. The logical way was to have the pcb leaving the edge connector extending through a pcb with a rectangular hole and then using a double sided pcb as like a motherboard with other holes and extensions passing through that.

I decided to use what I had at hand, a pcb extension card with tracks on it that I could cut up and modify.

This technique can create a a double, triple or multi-way adapter depending on how many...
 
I've got this working with my 4032, an 8050 and the SD2PET Future.

I used the IEEE splitter from Sven Peterson with the riser card added to allow an IEEE cable and the SD2PET Future to be plugged in at the same time.

github.com

GitHub - svenpetersen1965/PET-IEEE-488-Extension: This is a splitter and cable adapter for the Commodore PET IEEE-488 edge connector port

This is a splitter and cable adapter for the Commodore PET IEEE-488 edge connector port - svenpetersen1965/PET-IEEE-488-Extension
github.com github.com

I lifted pin 24 on UE1 in the 8050 to change the unit id to 9, plugged the 8050 into the IEEE port on the adapter, plugged the SD2PET Future into the riser card and have successfully copied files from the SD2PET Future to a floppy disk in the 8050.

Hope this helps.

Colin.
 

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That is a great adaptor. That is the one i have made. Perfect.
I have connected a switch on the pads as per the manual of the 8050 rather than leg lifting to be able to switch between 8 and 9.
But even with the 8050 turned off in either 8 or 9 the SD2PET will not have it.
I have now solved it by using a cbmSD-mini v1.2 by Steve J. Gray.
Works like a charm no issues, 8050 perfectly happy to live along side cbmDS-mini!
It's a shame I can't get to the bottom of what it doesn't like about the SD2PET
Would like to change the bin file that comes with the cbmSD-mini v1.2 to be device 9 permanently, if anyone can point me in the right direction.
 

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Each IEEE-488 device provides "light" termination with the resistor networks in the MC3446 buffer chips, these are also unreliable and you may just have a bad chip in the 8050 or even the PET - a powered off device is generally invisible on the bus, but not recommended...

You should be able to see which line is playing up by peeking the IO ports and turning devices on and off

Robin
 
Caterman said:
But even with the 8050 turned off in either 8 or 9 the SD2PET will not have it.
Click to expand...
I'm not sure if that could be a valid test. If there is a borderline condition affecting one of the bus lines with the 8050 connections to the bus (which I think there might be) with it sinking current as a fault condition, it likely will still be there with the 8050 unit de-powered. Have you scoped all of the bus data and control lines with the 8050 connected ?
You may be getting led up the garden path and a borderline logic level on the bus is only showing up as a fault when the 8050 is combined with the SD2PET and not the other units explaining why the SD2PET works with the other units and the 8050 works with other units but together they don't work.

One thing you could try , if you don't have a scope, is with the 8050 powered and not plugged onto anything, measure the voltages present on all the data and control pins on the connector. and document that on a table. Then with the unit switched off, and using a 5v source and a series 2.2k resistor and a meter in series in current mode, the negative of the 5V source connected to a ground pin on the connector, measure the current (if any) that passes into each pin with the meter, then document that. Also then without the 5V supply, and the unit switched on again, measure the current to ground via the 2.2k resistor and meter from the pins as well. With all that information, it might be possible to work out if there is a defect on one of the bus lines of the 8050, or not.
(Just the one thing to remember, if you are injecting current into a pin from the 5V source, or trying to sink current from a pin to ground, the 2.2k resistor must always be in series to limit the current and avoid any damage)
 
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Thanks for the info on testing IEEE-488 bus. I'm going to spend a little time enjoying using the 8050 now working with the cbmSD-mini. It's taken a while to get it working and at the moment I am of the opinion if it an't broke don't fix it.
I will have to pluck up enough courage to dive into testing the MC3446's

Just as an aside going back to the svenpeterson IEEE-488 extension I only could obtain the D sockets with clips that don't work with the cable connector security screws.
These screws are 3.5mm x 0.6 the same thread as UK electrical socket face plate retaining screws. So I took an old socket back box and removed the 2 brass threaded inserts and attached to D socket.
Works like a charm and no fear of the cable becoming detached!
 

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