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• CP/M-8000

  Keith • 11/09/2021 at 23:46 • 0 comments

  After wondering where 4sun5bu got the original source code from, I found it here:

  http://www.cpm.z80.de/source.html

  You can also find the manuals here:

  http://www.cpm.z80.de/drilib.html

  Archived and OCR'd at:

  CP/M-8000 System Guide

  CP/M-8000 Programmer's Guide

  CP/M-8000 User's Guide
  

• Compact Flash interface

  Keith • 11/09/2021 at 23:30 • 0 comments

  The original design uses an 8-bit data path. So it either works in the relatively slow 'PIO' mode, or wastes half the card data.

  A CF card can also present itself as a memory-mapped device, showing 1K of 16-bit words at a time.

  I think the CPU may be able to boot directly from the CF card in memory mode, bypassing the need for the ATmega device.

• Glue logic

  Keith • 11/09/2021 at 23:08 • 0 comments

  The TTL chip glue logic inputs and outputs are:

  Inputs  Outputs
  AS      ALE to two 74F573 chips
  !MREQ   RAM CS
  B/!W    RAM_ODD !CS
  A18     RAM_EVEN !CS
  A19     RAM !OE
  !DS     RAM !WE
  R/!W    
  A4      SCC !CS
  A5      CIO !CS
  A0      IDE !CS
  !DS
  ST0-3

  Adding up to 15 inputs and 9 outputs = 24 i/o pins total. More than a 22V10 has.

  The RAM active high CS output can be omitted by using MREQ in the active-low chip select equations.

  The AS and ALE pins can be omitted if kept in an external inverter.

  The CIO select output pin is not currently used (freeing one pin).
  

  The steps above reduce the pin count to completely fit in a single 22V10 chip.

  The SCC select output could be used to select a USB FIFO interface instead.
  

  I have attached a first draft logic equation, but not tried compiling it yet,

• Project proposal

  Keith • 11/09/2021 at 14:48 • 0 comments

  I propose starting from an existing CP/M-8000 machine project, which looks like this:

  My project proposal is to

  • construct on a Eurocard (160x100 mm)
  • replace multiple TTL chips with GAL chips
  • add a FIFO-interface USB module (replacing the Z8530 UART and serial USB module)
  • add an STEbus interface

  4sun5bu's sparsely-populated board has about 48x84 holes and looks about 5.4x9.25 inches or 235x137 mm. This is twice the area of a 160x100mm eurocard. I think it should fit.

  4sun5bu says that 74F logic should be used, because 74LS is not fast enough.
  I shall take that as a warning to pay attention to timing.

  The Compact Flash interface is unbuffered. 
  You might be able to use an IDE/PATA drive 
  with a very short cable, not the long cables used in old PCs.

  I intend to port some or all of the glue logic to GAL chips.
  This will make changes quicker than rewiring.

  Parts list:

  Qty Device Package Comment

  1 Z8001 DIP48 Essential
  2 RAM DIP32 Essential
  1 USB DIP24/40 Replaces Z8530 serial chip 
  1 ATmega164 DIP40 Controls boot-up

• Research

  Keith • 11/09/2021 at 14:07 • 0 comments

  One of the first parts in technical papers is a survey of existing works. 

  Z8000 board (the Trump Card) by Steve Ciarcia in Byte magazine

  Hardware: A full-length ISA board as a slave to the PC. Most of it is a massive array of sixty-four 4164 DRAM chips giving 512K of RAM. These could be replaced by a a pair of 512K SRAM chips. Communication is through a 2K RAM with counter supplying the address lines.

  Software: It ran a BASIC interpreter but I can't find it in any form on the web.

  Documentation: Several articles in Byte magazine. 
  

  Z8000 board by Rolf-Dieter Klein

  Hardware: I believe this is documented in one of his books, but I can't find a copy online.

  Software: There is a listing of a Z8000 BASIC interpreter (and the Z80 BASIC it was based on) in his book. I've had a go converting the listing into a form that can be assembled by non-Z8000 assemblers, but I have nothing to test it on yet.

  Documentation: His books are in the German language. 

  Z8000 board by Christopher Ramage

  Hardware: He has made a PCB for this. An Atmel Arduino board is used for boot-up and debugging.

  Software: Not publicly available.

  Documentation: Just the circuit diagram.
  

  Z8000 S8000 system by Zilog

  Hardware: Lots of documentation on this website but the S8000 system is very big and used lots of small-scale TTL and chips of the period. So it is bigger and more complicated than necessary in 2021. 
  

  Software: Many EPROM images with source code.

  Documentation: Plenty. Some of the scanned circuit diagrams have been redrawn on a modern ECAD package, and are much easier to read.

  Z8000 board videos by 737MHz

  Hardware: Constructed on prototyping board.

  Software: Runs BASIC. 

  The videos show the board running BASIC but there is no verbal or written commentary.

  Documentation:  Nor links to any documentation. 

  The PC downloading software has a Japanese user interface, so searching for Japanese web-pages is a rich source of links.

  Z8000 projects on Github

  tgtakaoka has done a lot of work writing assemblers, and supporting the Z8000.

  4sun5bu has a Z8001 project built on prototyping board with circuit diagrams and software. It boots from a microcontroller, and runs CP/M-8000. It is the most advanced project I can find.

  4sun5bu is also this chap: https://www.blogger.com/profile/10308244904742468931 whose Japanese name translates to 4 inch 5 minutes. I think it refers to a size of dagger. His  blog  https://choisaki.blogspot.com/ has a lot of Z8000 stuff.

• BASIC interpreter

  Keith • 11/07/2021 at 04:11 • 0 comments

  2021-05-07

  I've found source code for a Z8000 BASIC interpreter and monitor, in an online book by Rolf Dieter Klein. I did a quick check of the OCR. My Chrome browser can translate the German to English, not perfectly but fairly readable.

  The OCR'd listing is very poor, so that will be a lot of work to restore to usable source code.

  Jurjen Kranenborg reports he is developing a monitor and BASIC interpreter based on Klein's code. https://www.kranenborg.org/z8000/software/index.htm but no sources are visible yet. I have had a go myself, but have no Z8000 assembler yet.

  2021-11-05

  Lacking an assembler, and needing a reference to check an assembler output, I converted the book's listing into something that can be assembled as a collection of labels, hex words and ASCII characters. The original assembler statements are made comments. This involved a lot of editing and typing the hex data in by hand!

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