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Questions tagged [cp-m]

For questions related to the CP/M operating system by Gary Kildall.

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52 votes
7 answers
13k views

Why does the Commodore C128 perform poorly when running CP/M?

I have seen several claims of poor performance of the C128 when running CP/M, and would like to better understand these claims, especially in comparison to other CP/M machines of the early to mid-...
Brian H's user avatar
  • 60.9k
26 votes
12 answers
5k views

Why did CP/M and MS-DOS use the BIOS instead of their own drivers to access hardware?

Modern versions of Windows (and other modern operating systems I suppose) have their own drivers to access hardware. But as I have read, in the old days, if CP/M or MS-DOS wanted to access hardware, ...
user7681202's user avatar
  • 1,857
5 votes
1 answer
790 views

Is there a way to boot CP/M automatically on a Z80 RC2014?

I'm using the RC2014 (Z80), running CP/M. The "24886009" ROM chip (photo below) comes with 32k BASIC, 56k BASIC, SCM and CP/M for SIO/2 serial. When you run CP/M from the RC2014 ROM, you ...
Nick Bolton's user avatar
45 votes
10 answers
16k views

Fastest non-emulated CP/M Z80-based computer ever built?

What were the fastest CP/M computers ever built? I'll restrict this to the Z80 variant of CP/M, no CP/M-86, CP/M-68k etc. Z80 compatibles with higher clock frequencies or more instructions/clock or ...
dirkt's user avatar
  • 28.4k
25 votes
3 answers
3k views

Why does CP/M use CALL 0005h for its syscalls?

CP/M, the operating system for Intel 8080 and Z80 (and others as well, but later) used to call 0005h for syscalls. The application would load the syscall number into a specific register (I think it ...
Omar and Lorraine's user avatar
23 votes
6 answers
7k views

Why did the Z80 with 4-bit ALU out-perform the fully 8-bit Intel 8080?

Looking at the development and architecture of the Z80, it appears to be a scaled-down, cost-reduced (in terms of total system cost), clone of the Intel 8080. It only used a 4-bit ALU. I assume this ...
Brian H's user avatar
  • 60.9k
19 votes
8 answers
4k views

CP/M in fewer than 80 columns

The standard for business computing in the seventies and eighties was 80 columns, and CP/M was primarily for business computing, so it's unsurprising that CP/M typically ran in 80 columns. For example,...
rwallace's user avatar
  • 63.1k
14 votes
4 answers
2k views

Did CP/M provide compatibility for screen-based programs?

I refer here to 'screen-based programs' that are not actually graphical, but take full advantage of the screen as a two-dimensional array of 80x25 characters, as opposed to typical 'command-line ...
rwallace's user avatar
  • 63.1k
10 votes
4 answers
2k views

How do you run a program automatically when CP/M 2.2 loads?

Following my question on booting CP/M automatically on RC2014 Z80, I'd like to run a program after CP/M starts, similar to how autoexec.bat works on DOS. I see that CP/M 3 has PROFILE.SUB which would ...
Nick Bolton's user avatar
6 votes
2 answers
1k views

Are there any drivers available to use DivMMC on the Spectrum +3e with CP/M plus?

Heading says it all. I have a Spectrum +3 (with +3e ROMs if that makes any difference) with a DivMMC SD card interface. This works fine in +3e mode, but as I like to use the +3 with CP/M plus (...
tofro's user avatar
  • 35.6k
2 votes
1 answer
237 views

Why does Z80 RC2014 ROM image 88 not have CP/M or BASIC boot options?

While trying to boot to CP/M automatically on my RC2014 Z80, I encountered a problem getting SCM to show a CP/M boot option. According to the docs, ROM address 4000 (88 on the ROM label) is SCM with ...
Nick Bolton's user avatar