ISA bus slave NS32016 processor board

I've added tech data so you can build your own PD32 or at least the reconstruction of it.  There are schematics, PCB layout, two BOMs, 3D rendering images, and Gerber files.

If anyone decides to make their own PD32 using the supplied Gerber files please post here with your results.  Especially if any changes are necessary and/or you find improvements.

Would really like to see your results of a PD32 build.  Thanks!

There is a Definicon cross-assembler but it is an MSDOS executable binary so I can't run it on my Linux PC nor can I compile it for Linux because there is no source-code.

There is C source code for one in Dr. Dobbs' Journal. The OCR text is not good because all the OCR tools I can use for free try to automatically recognise text in columns, with no way to specify single-column operation. Which mangles the order of source code scans.

Several days of tedious salvage work later, I've got the 32000 cross-assembler to the point where it compiles, but it crashes with a memory segmentation fault. Probably trying to do something that used to be okay on MSDOS but not on a modern OS.

I don't have enough spare time to get it working, but there are many capable coders out there, and I am sure one of them could get it running fairly quickly.

I notice that most of the code is doing lexical analysis, splitting the source into lines and words, turning words into symbols and numbers. 

I have just started learning Python, and it has vast libraries for doing this kind of work. If I were to write one from scratch, I would start with Python to make the job easier and quicker.

The PD32 PCB routes in in FreeRouting as a 2-layer board, however, based on what I've read the NS32K chipset seems rather sensitive to signal quality.  A 2-layer board is less expensive, but if a 4-layer design is more likely to work, then I think that's the way to go.  

It seems there were some articles and/or letters in MicroCornicopia after the original PD32 article suggesting PCB quality caused a lot of problems to the initial roll out in 1986.  They also used an improved 4-layer board to improve signal quality, so I think it is prudent to do the same.  

The good news is the PCB easily routes as a 2-layer board so transitioning to a 4-layer PCB should be no problem.  Just add two internal copper layers, one for GND and the other for VCC.

Octopart links to chips in BOM

13    U1, U3   PAL20L8 or better e.g. 22V10
14    U11,U12  27256    
15    U14,U15  74ALS573 Transparent latch, 8-bit
16    U2       74LS74    
17    U4       74LS32   
18    U5       74LS646 Octal bus transceivers and register
19    U6       74ALS00   
20    U7       74LS175   
21    U8       NS32202 Interrupt Control Unit
22    U9       74LS30   
23    U10      74LS04   
24    U13      NS32081 Floating-Point Co-processor
25    U16      NS32201 Timing Control Unit
26    U17      NS32016 Processor
27    U18      DP84412 Replace with PAL16R6 or better e.g. 16V8
28    U19      NS32082 
29    U20      DP8419  DRAM address multiplexer and refresh row counter
30    U21      74S32   
31    U22      74LS08

The PAL chips are no problem, I have original PAL chips and the logic can be ported to modern GAL chips.

UT Source have the DP8419 and DP8409

I feel completely content if a hardware project boots up and says "Hello world!".

After that, I hand over to software hobbyists. Hardware tends to have a completion point, software does not.

If you have the time and skills, it is possible to get this board running Unix, though I wonder what you could do to impress someone through a text-only interface.

The board and Host PC communicate through an 8-bit bus, although the board does not have any 8-bit latches to store data. Maybe those would be on the Z80 board?

I'm pretty sure this is mainly the user interface terminal with the ability to transfer something like intel hex files. This should not be too hard to create.

I feel it could be replaced by a USB-FIFO type interface.

The design includes the source code, but no binary image. We need a 32000 assembler for that. Which I thought would take some finding because the 32000 family never took off commercially. Thankfully, I was wrong!

http://cpu-ns32k.net/Crossass.html

I tried using this to assemble the PD32 firmware - without success. It seemed to want carriage returns with linefeed, and not have colons before equates. Conditional assembly didn't work. I think the syntax is significantly different, and I don't have a manual to tell me what it is. If it can't do conditional assembly it may not be up to modern standards.

Hex numbers are not the usual $FF, or C style 0xFF, but x'FF which is very strange. So the h'FF needs changing to x'FF.

I don't have time to investigate this at the moment.

It isn't hard to split the firmware into odd and even bytes when required.

Later, we will need a C compiler. Also hard to find. Here seems a good place to start:

http://cpu-ns32k.net/Gnutool.html

Start by asking what are the worst mistakes that could happen, and work downwards from there.

For example, check if a hole is in the right place before you check it is the right size.

I've seen boards with the wrong size, the components back to front or upside-down, so I know what to look for!

This involves printing it and the original, then marking checked tracks with a highlighter pen. Not difficult but you do have to be patient and meticulous. I can do this.

2024-02-05

I printed the old and new schematics on A3 paper. 

First job will be to check the pin numbers of each part match.

2024-02-16

Checked final sheet today. All sheets now checked.

No discrepancies, although the original numbers header pins in an unconventional way.

The capacitor for BBG looked wrong (+ve to ground) until noting that it is the decoupler for a negative bias generator.

Original circuit omits power and ground pins, so I have not been able to correlate them.

I used to do CAD librarian work so I can certainly do this.