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DATA General Nova 3 serial console pins
- Thread starter old_68k
- Start date
pbirkel@gmail.com
Veteran Member
Well, the Nova-line back panels aren't bussed that way. Serial I/O connections will be specific to the slot in which the applicable controller is located. In the Nova 3 that *conventionally* would be Slot 4. Take a look at "001-000853-12__Nova_3-12_Backpanel_005-006397__1975-1978.c.pdf" or page 16 in "DG_Schematics_Vol_I__Nova_3.pdf" (attached) -- which applies equally well to the smaller Nova 3 back panels; there will just be fewer "MEMORY OR I/O" slots.
The next question will be the nature _and configuration_ of the I/O controller that you have installed. Post a good photo of the component side. In general it will be labeled in the etch by the left handle and there will be a 107-xxxxxx number in the etch by the right handle as well as a set of labels on the board stiffener -- although those are often missing. Typically there will be a base configuration of the controller board that handles addressing and the back plane interface, and then a set of control/capability options that may be installed; some are more commonly installed than others so it's important to determine exactly what _your_ controller has implemented in terms of options (capabilities).
Conventionally the I/O controller would be either a "CASSETTE IO" or possibly a "BASIC IO CONTROL" board. In "DG_Schematics_Vol_I__Nova_3.pdf" the "CASSETTE IO" controller is documented starting at page 47. The top-center of page 51 (titled "ASYNCHRONOUS CONTROLLER") documents the internal cabling (paddleboard connector, back panel pins, and socket connector) for Options 4077 and 4078 on the "CASSETTE IO" controller. The same page documents the jumper configuration for various baud rates (110 ... 9600 baud). You need to check your controller and installed options to determine whether it's populated to support 20 mA current loop or EIA (RS-232) voltages! The earlier "BASIC IO CONTROL" board operates similarly although while the supported devices are pretty much entirely different (as is the process of jumper configuration) the cabling for the serial interface will be the same.
In general you'll want to attach to pins A85 (TTO) and B69 (TTI) on Slot 4. Note the pair of extra pins between the "A" and "B" connectors there.
Here's a photo with three pins being "tapped" for a serial I/O connection on & adjacent to the Slot 4 "A" connector; a comparable photo of your back panel would be helpful:
The next question will be the nature _and configuration_ of the I/O controller that you have installed. Post a good photo of the component side. In general it will be labeled in the etch by the left handle and there will be a 107-xxxxxx number in the etch by the right handle as well as a set of labels on the board stiffener -- although those are often missing. Typically there will be a base configuration of the controller board that handles addressing and the back plane interface, and then a set of control/capability options that may be installed; some are more commonly installed than others so it's important to determine exactly what _your_ controller has implemented in terms of options (capabilities).
Conventionally the I/O controller would be either a "CASSETTE IO" or possibly a "BASIC IO CONTROL" board. In "DG_Schematics_Vol_I__Nova_3.pdf" the "CASSETTE IO" controller is documented starting at page 47. The top-center of page 51 (titled "ASYNCHRONOUS CONTROLLER") documents the internal cabling (paddleboard connector, back panel pins, and socket connector) for Options 4077 and 4078 on the "CASSETTE IO" controller. The same page documents the jumper configuration for various baud rates (110 ... 9600 baud). You need to check your controller and installed options to determine whether it's populated to support 20 mA current loop or EIA (RS-232) voltages! The earlier "BASIC IO CONTROL" board operates similarly although while the supported devices are pretty much entirely different (as is the process of jumper configuration) the cabling for the serial interface will be the same.
In general you'll want to attach to pins A85 (TTO) and B69 (TTI) on Slot 4. Note the pair of extra pins between the "A" and "B" connectors there.
Here's a photo with three pins being "tapped" for a serial I/O connection on & adjacent to the Slot 4 "A" connector; a comparable photo of your back panel would be helpful:
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Thank you for the PDF and related info. Where do you find these manuals ??? I looked every where. on page 24 of this drawing is shows the TTY P2 connector. I will attach a photo of my back plane and one from a on line source. Mine system has a Cassette I/O /4078 in slot 4. 
MY_BP Is what I have. the other is from the web. Is this TTY cable Layout available in some other document. Just guessing this is what I need to come up with.
Thanks, Again, Jerry
MY_BP Is what I have. the other is from the web. Is this TTY cable Layout available in some other document. Just guessing this is what I need to come up with.
Thanks, Again, Jerry
pbirkel@gmail.com
Veteran Member
Currently the best source is http://www.novasareforever.org/archives/documentation/dg.hw/dg_hw_cpu_nova
Also see https://bitsavers.org/pdf/dg/ and https://archive.org/.
Presumably then it's almost entirely unpopulated (no cassette or RTC support) with just the TTY interface functional. If there's a label stating "4078" then you have an EIA (RS-232) interface by default ... although it may have been disabled.
So page 51 of DG_Schematics_Vol_I__Nova_3.pdf is directly applicable *BUT* you need to determine the status of Option 4078 as to whether a 20 mA current loop interface or EIA (RS-232) interface is currently enabled. Check for the presence of U76/U77 and review the information on the lower-right of that page.
So you have a DG-supplied internal cable that routes TTO (green) , RDR RUN (white), GND (black), and TTI (red) to a rear paddleboard or socket connector; which depends on your configuration. A "paddleboard" will be a small PCB installed as one of a stack of them in the right-rear of the chassis; it may have an edge-connector for attaching an external cable. Something like this, although yours would likely be smaller:
A "socket connector" will be a conventional DB9-style cable connection. So here's the pinout in either case:
Given that RDR RUN (used to signal a Teletype M33 to attempt to read a paper tape) is wired then (at least as-shipped) there would be a configuration of your system that did indeed support a 20 mA current loop interface.
You can ignore the blue jumper wires for the moment; just don't remove them :-}.
Do you have a tested & operational Teletype M33 (aka ASR33 or KSR33)? If so then examine its manuals. If you have a KSR33 then RDR RUN can be ignored. If you have an ASR33 then there's a separate "DGC TELETYPE" interface-PCB to convert from the TTL RDR RUN signal to what you'd need internal to the ASR33.
If you don't have a M33, then what do you specifically mean by "TTY"? If you mean something using TTL-level signalling that you can hook up to a modern USB interface (e.g., like these: https://www.amazon.com/dp/B0DDGLRY1D) then that's definitely *not* a Teletype, nor is it actually EIA (RS-232). Keep in mind that the Nova 3 is a 50 year old design/implementation. Modern assumptions simply don't apply ...