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Using CPM
The RC2014 Pro runs CP/M as standard, or a CP/M Upgrade Kit can be added to the RC2014 Classic or RC2014 Plus. The implementation supplied is CP/M 2.2 and, as with BASIC, this has been modified by Grant Searle and is used with his kind permission. A guide to getting CP/M running can be found here.
The CP/M Monitor has been modified to allow it to be used with the Pageable ROM Module and CP/M itself has been modified for either the 68B50 ACIA (“1”) or SIO/2 UART (“6”). Note that the CP/M Monitor runs from ROM as the RC2014 is booted up, and CP/M runs from the compact flash after it has been invoked from the Monitor.
The original files can be found on Grant Searles website.
The RC2014 modifications can be found on GitHub
When you boot up the RC2014 you are greeted by the following message;
Press [SPACE] to activate console
This is sent out to both Port A and Port B on the SIO/2 serial module, or sent out twice on the 68B50 serial module.
After hitting space, you have the following prompt
Z80 SBC Boot ROM 1.1 by G. Searle
Type ? for options
Typing ? will give you the following options
R – Reset
BC or BW – ROM BASIC Cold or Warm
X – Boot CP/M (load $D000-$FFFF from disk)
:nnnnnn… – Load Intel-Hex file record
Note that on the RC2014, the BC and BW options are not active. If you wish to run BASIC, you can change the jumpers on the ROM module, or download BASIC for CP/M. Using BASIC under CP/M gives you the ability to load and save programs from the CF card, which is unavailable for ROM based BASIC
Hit the X key, followed by Y and you are in to CP/M
Z80 CP/M BIOS 1.0 by G. Searle 2007-13
CP/M 2.2 Copyright 1979 (c) by Digital Research
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Several alternate implementations of CP/M 2.2 are available for the RC2014. As is typical for CP/M, they differ only in their BIOS coding which is dependent on their hardware requirements.
These include:
- Grant Searle's implementation, as described above, uses the RC2014 Pro as a basis.
- RomWBW implementation, additionally requires the 512k ROM 512k RAM module, provides substantial hardware flexibility, HBIOS API, and loads and runs from ROM.
- CP/M-IDE implementation, uses RC2014 Plus as a basis, requires the IDE module, provides fast FAT32 formatted disk access and serial interfaces, and loads and runs from ROM.
Additionally an improved CP/M implementation called Z-System (consisting of ZSDOS and ZCPR) is included in the RomWBW platform and, whilst not 100% compatible with CP/M, provides some significant improvements for advanced users.
There are two OS variants included in RomWBW and you may choose which one you prefer to use. Both variants are included in the pre-built ROM images. You will be given the choice to boot either CP/M or Z-System at startup.
The traditional Digital Research (DRI) CP/M OS is the first choice. The Doc directory contains a manual for CP/M usage CPM Manual.pdf. If you are new to the RetroBrew Computer systems, the recommendation is using the CP/M variant to start with simply because it has gone through more testing and you are less likely to encounter problems.
The other choice is to use the most popular non-DRI CP/M "clone" which is generally referred to as Z-System. It is intended to be functionally equivalent to CP/M and should run all CP/M 2.2 code. It is optimized for the Z80 CPU (as opposed to 8080 for CP/M) and has some potentially useful improvements. Please refer to ZSDOS Manual.pdf and ZCPR Manual.pdf for more information on Z-System usage.