dietrich-l / cpm-65 Goto Github PK

CPM-65
===========
Dietrich Lausberg <[email protected]>
https://github.com/dietrich-l
This repository contains CPM-65, 
a CP/M-80 analogue operating system for 6502 based microcomputers

Elektor Junior Computer - system setup

Screenshot system disc
 System Requirements

6502 processor
12 kByte RAM (not tested)
6532 I/O chip for the system timer (could be replaced by a 6522 or other)
min 1 Floppy drive
Serial-I/O
My system is a heavily modified and expanded Elektor Junior Computer with 57 kB RAM. 
For system components and memory map see separate docs
 System Structure

CPM-65 consists of 3 layers:

BIOS Basic I/O system - currently 3 kB, could be reduced to 2kB 
  by removing SCSI and I2C drivers. Drives can be A-H non consecutive. 
  I/O console is serial TTY 1200 - 9600 Baud
BDOS Basic disc operating system - this is the CPM-65 kernal. Size 2 kB
CCP Console command program - a simple console which only allows 
  to invoke CPM-65 programs. No resident commands. Size 1 kB


 File & Disc Format


Filenames are CP/M-style d:filename.ext with d <Drive A-H>
Programs must have .COM as extension and are loaded to $0200 and started there.
The directory structure is nearly CP/M-compatible. Disk images can be read with appropriate  tools 
like CPMTOOLS, CIFE (CPM Image File Explorer) or CpmtoolsGUI.
A disdefs file is in the IMAGES section. 
Please use a recent version because parameter extentsize 8192 is needed.

The Disc format is typically 40 tracks/ 16 sectors/ 256 byte/sector. It is defined in the BIOS. 
The BDOS operates on sector numbers. 
Maximum sector number is $800 blocks with $20 sectors = 65536 sectors � 256 bytes = 16 MBytes
Software List

All software is supplied as assembler files to be assembled with the CPM-65 assembler. 
In case you wish to use a different assembler, the syntax has to be adapted accordingly.

Documentation

Currently the documentation of CPM-65 is sparse and only for my personal needs. 
I plan to write appropriate docs over time. If there are any whishes, please open a DISCUSSION
Errors

The CPM-65 system has now seen more than 30 years of service. Currently there are no known errors.
However, since an error free software does not exist, please report any errors in the ISSUE section
Other related systems

When I started the development of cpm-65, I was blissfully unaware of any other aproaches. 
However there are some, most notably:

DOS/65 by Richard Leary. There is a limited compatibility
OUP/M  by Jiang - Xiong Shao. Published 1983, no further development
CPM65 by David Given, published 2022

Redistribution

Source code, and all documents, are freely redistributable in
any form. Please see the the COPYRIGHT file included in this
Repository.