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NOVA 445

A Data General NOVA-compatible computer based on the Fairchild F9445 microprocessor

Steve TonerSteve Toner
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  • Description
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  • Files 7
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  • Components 0
  • Logs 20
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  • Instructions 0
  • Discussion 8
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  • Steve TonerSteve Toner

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This project was created on 12/15/2019 and last updated 6 months ago.

Description

System Requirements:
1. Emulate Data General NOVA computer
2. Use Fairchild F9445 microprocessor
3. Include provision for switch-and-light front panel
4. Include provision for ROM-based monitor program/debugger
5. Capable of running Data General's Real Time Disk Operating System (RDOS)
6. Full 32K words (64KB) of RAM available when running loaded code
7. Peripheral support: TTY I/O, Real Time Clock, emulated disk subsystem (minimum 1 drive, preferably more)
8. Include provision for graphic display (min 256x256 pixels)

Files

asm445.pl

Crufty absolute assembler for NOVA 445 RAM code. Written in Perl, generates .AB (Absolute Binary) files per Data General document 093-000003-06 (Binary Loader User's Manual).

pl - 35.27 kB - 12/05/2020 at 02:47

Download

asm445-r.pl

Crufty assembler for NOVA 445 ROM code. Written in Perl, generates .hex files for low & high byte.

pl - 31.60 kB - 12/05/2020 at 02:46

Download

LDTST.LST

Example program used to test absolute assembler & binary loader.

lst - 5.69 kB - 12/05/2020 at 02:42

Download

schematics033120.pdf

Preliminary Graphics processor board schematics (subject to change)

Adobe Portable Document Format - 500.89 kB - 04/01/2020 at 02:23

Preview
Download

RAMTST.LST

Example asm445 listing output (Monitor RAM test)

lst - 3.21 kB - 03/21/2020 at 20:34

Download

View all 7 files

Project Logs
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  • Paper Tape Reader Emulator

    Steve Toner • 04/03/2021 at 01:51 • 0 comments

  • Absolute Assembler/Binary Loader

    Steve Toner • 12/05/2020 at 00:02 • 0 comments

  • ROM Monitor

    Steve Toner • 11/17/2020 at 06:35 • 0 comments

  • Testing the Serial Port

    Steve Toner • 11/08/2020 at 03:12 • 0 comments

  • Testing the V2 Graphics Board

    Steve Toner • 09/11/2020 at 20:31 • 0 comments

  • Revising the Graphics Card

    Steve Toner • 08/08/2020 at 03:30 • 0 comments

  • New File Uploaded

    Steve Toner • 06/14/2020 at 16:43 • 0 comments

    Found & fixed a bug in the assembler.

    Uploaded new version of asm445.pl

  • Bitten By Bit Order

    Steve Toner • 06/11/2020 at 22:55 • 0 comments

  • Video Output

    Steve Toner • 06/05/2020 at 02:46 • 0 comments

  • Graphics Board

    Steve Toner • 05/27/2020 at 01:52 • 0 comments

View all 20 project logs

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Robert Armstrong wrote 02/08/2020 at 22:23 • point

Any updates on this design?  I have two F9445 chips myself and would be interested in seeing what you come up with.  I'd also love to find a 9470 console chip, if anybody has one!

  Are you sure? yes | no

Steve Toner wrote 02/22/2020 at 05:34 • point

Update posted.

I don't know how many of the support chips actually exist.  The datasheets that are out there on the web say "Advance Product Information" for the FPP (9443), MMPU (9444), DMC (9446), IOBC (9447), PMI (9448).  The F9470 does appear to be an actual part as of the January 1983 Microprocessor Products Data Book.  A web search does show www.4starelectronics.com claiming to have 46 9470s (and maybe some F9444s? These may be an 8-pin microcontroller) in stock as of right now...

  Are you sure? yes | no

Robert Armstrong wrote 02/22/2020 at 16:01 • point

Thanks for the pointer.  I submitted an RFQ for qty 2 F9470s, and I'll post if I get a response.  I'm not hopeful, but maybe I'll get lucky.  Have you posted a schematic for your Nova 445?  I'm not familiar with I2L logic, and I'm interested to see what you did with the Iinject pin.  Did you just use a resistor to Vcc, or did you implement a constant current source to drive it?  Thanks again.

  Are you sure? yes | no

Steve Toner wrote 02/22/2020 at 18:16 • point

I haven't posted the schematics yet.  I usually like to wait a while until any major mistakes reveal themselves :-)

I just used a 10 ohm resistor (10W/TO-126 case + heatsink -- you can see it below the CPU socket in the thumbnail for the "Introducing..." video) for the Iinj.  I don't think it needs anything fancier than that.  One thing about the processor though: a logic '1' output is only about 3.6V.  In spec to drive a TTL load, but much lower than what you're probably used to seeing in typical TTL/NMOS/CMOS circuits...

  Are you sure? yes | no

Robert Armstrong wrote 02/22/2020 at 18:47 • point

Thanks.  It'd be easy enough to construct a constant current source using a 3 terminal linear regulator, but I don't really understand all the trade offs in how this affects the operation of the uP.  Good to know that a simple resistor will work.

I was aware of the TTL output levels; I'm planning to use 74HCT or ACT parts for things that are directly driven by the 7445.  These are CMOS parts with input thresholds skewed to match bipolar TTL.

  Are you sure? yes | no

Steve Toner wrote 02/22/2020 at 19:38 • point

OK, I've posted the current schematics for the CPU Board.
I used a mix of different happy families of chips.  Mostly 74F (and U5/U6, though shown in the schematic as AS, are actually F), but some S and LS (had 'em) and the bus transceivers (U8/9, U20/21) are ABT...  Then there's a plain old 7406 & 7407 and one ALS part just for good measure (U14, shown in the schematic as an S)  Date codes range from 1977 to yesterday :-)

  Are you sure? yes | no

Ken Yap wrote 12/15/2019 at 07:19 • point

Great! Looking forward to seeing this bit of computing history come alive again.

Did you happen across the CPU or did you purposely seek it out? I notice that it uses I3L. I2L was described in https://hackaday.io/project/159059-adventures-in-time-integrated-injection-logic

  Are you sure? yes | no

Steve Toner wrote 12/15/2019 at 16:12 • point

I sought it out.  The DGC Nova was the first computer I used/learned about/programmed, and I actually interviewed at Fairchild back when its predecessor, the F9440, had just been released.

They are quite hard to find these days, but I managed to acquire two...

  Are you sure? yes | no

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