Computers Overview
Commodore PET
Sinclair ZX80
Sinclair ZX81
BBC Micro
Commodore 64
Sinclair Spectrum
Memotech MTX
    About
    Library
    Manuals
    Options
    Photos
    Projects
      CFX
      Hardware Hacks
      Legacy (1980s)
      MAGROM
      MTXPlus+
          Architecture
          Design Data
          Firmware
          Parts
          Software
              CP/M
                  BDOS
                  BIOS
                  CCP
                  Usage
              Compatibility
      PAL Reader
      Programmers
      ReMemotech
      ReMemorizer
      SDX
    Repairs
    Software
    Tools
    User Groups
    Video Wall
Memotech CP/M
Atari ST
DEC 3000 AXP
OpenVMS
Raspberry Pi

 

 
 
 

MTX Plus+ CP/M

 

 

I had originally thought that getting CP/M running on MTXPlus+ would mean writing a custom BIOS from scratch (see below).

However, Martin has been busy again and ported Andy Key's REMEMOrizer ROM code to MTXPlus+. The screenshot shows MTXPlus+ booting CP/M from a Compact Flash card which contains a copy of Andy's CP/M system disk included with REMEMOrizer.

At this point, the software is unfinished - for example, the system does not currently support Memotech FDX/SDX colour attributes, but Martin has made a great start. The system can run CP/M transient programs such as "PIP" and "STAT", third party programs such as CRCK44 as well as Memotech utilities such as MTX/MTXL which switches the system into 40 column MTX BASIC mode. The photos below are a selection of the screen displays from Martin's TV - the images give a flavour for how the display looks, but do not do justice to the video output - the quality is much better in reality.

 

The output from "STAT DSK:", showing the structure of the disk (CF card partition) as seen by CP/M - copied from REMEMOrizer :

65472 x 128 byte Records, i.e., 8MBytes

512 Directory entries

2 Reserved tracks (for CP/M)

With its 512KB of RAM, MTXPlus+ also supports a Type 52 RAM disk like REMEMOrizer.

This screenshot shows the system running the RAMDISC submit file from REMEOrizer. Drive "F" has been created as a 320KB RAM disk and a number of CP/M tools have been copied to it, allowing them to run from RAM.

Screen shot of the system running NewWord with VDEB.DOC open for editing.
Martin has been busy again . . . . .

NewWord now running in colour - the attribute code is still not finished, but this is a big step forward.

 

Display Comparison

REMEMOrizer

VGA Output
Aspect Ratio 4:3

MTXPlus+

NTSC RGB Output
Aspect Ratio 16:9

 

 

Original Concept

My ultimate aim is to get CP/M running on MTXPlus+ to enable me to run some of the large range of software that is available for CP/M. Initially, I will be using CP/M 2.2 - the same version as used by the original Memotech FDX and SDX, as well as the BBC Micro, but may ultimately try to migrate to CP/M 3 which supports memory paging, subdirectories and file date/timestamps.

My Memotech MTX focused CP/M pages provide a high level overview of CP/M, but the key principle is that CP/M was written to be transportable, different systems can run the same software programs with only a limited quantity of machine specific programming at Operating System level. All CP/M systems have their own Customised Basic I/O System (CBIOS, or just BIOS), used to interface the machine specific hardware with the high level CP/M function calls for such items as the keyboard, video display and disk drives.

This page is a repository for useful information that may be used while developing the MTXPlus+ CP/M BIOS. A number of Digital Research documentation for CP/M 2.2, including the CP/M 2.2 System Alteration Guide can be found on my CP/M manuals page.

 

Resources

Title Source Description
nzmon.mac

oldcpusrus Hack of an old S.D.Systems monitor program, updated to include bank switching logic, a .hex file download, and a far more extensive floppy disk interface that the original. It uses the Zilog SIO/2 serial chip for the system console.
cbios.mac

A preliminary CBIOS written for a Z80 prototype being built by Roger Hanscom of oldcpusrus
block.prn

Original block/deblock code from Digital Research
bios.mac

oldcpusrus A generic BIOS from "The Programmer's CP/M Handbook" by Andy Johnson-Laird
cpm2-htm.zip

The Unofficial

 CP/M Website

Digital Research CP/M 2.2 Operating Manual in html format, including a chapter on CP/M Alteration and an example "bare bones" BIOS.
     
     
     

mailto: Webmaster

 Terms & Conditions