4 ms·

Early Digital Research CP/M Source Code

41 points by chl 12y ago

toolslive 12y ago
I think CP/M is where the driver letters in windows came from. Now I know who did it.
- Moto7451 12y ago
  MS DOS is a clone of CP/M. Since Windows originally ran on top of DOS it inherited the drive letter system.
  - MrBuddyCasino 12y ago
    The sources for MS DOS 1.1 and 2.0 are available as well, if you'd like to compare them: http://www.computerhistory.org/atchm/microsoft-ms-dos-early-source-code/ http://www.computerhistory.org/atchm/microsoft-ms-dos-early-...
- bodyfour 12y ago
  A lot of conventions in CP/M are similar to DEC operating systems of that period (RT-11, RSTS/E, etc) For instance in RT-11 files had the same "device:filename.ext" format. However the device spec was 2-3 characters, not just one letter. There may be earlier antecedents as well.
- pjmlp 12y ago
  Symbian and Amiga OS also have device names. As for Windows, in the NT line you can also refer to drives via \Devices\... when using object paths in Windows API.
templeos2 12y ago
I have God's endorsement. Go educate yourself on why mine is God's official temple. You will eventually stop being in denial.
Zardoz84 12y ago
And they forgot to put the posterior evolution of CP/M , with the multiuser versions, and later in a compatible "clone of MS-DOS", called DR-DOS.
pervycreeper 12y ago
One thing I never quite understood: in a home computing context, what is the advantage of having a system like CP/M, compared to, say, using a BASIC interpreter which includes the same commands?
- nilsimsa 12y ago
  The hardware was not quite standardized at that time so CP/M had a layered structure consisting of a BIOS, BDOS and the command line processor. The BIOS was the hardware abstraction layer and was ported to the specific combination of hardware. The BDOS provided the file system and the command line processor provided a standardized interface. On top of this you would run the BASIC interpreter as an application.
  - to3m 12y ago
    Right, but while BASIC is running, the command line processor isn't. So if you want to run a command... what then? Presumably the BASIC has to reimplement it. I guess that's the point. Having this layered approach is valuable, but having a separate command processor, perhaps less so. (I never used CP/M but I used to have an Acorn BBC Micro and that had the command line processing built in to the OS, in its equivalent of the BIOS, I suppose to work around this very issue. All an application needed to do was get a string from somewhere, then pass it to the appropriate OS routine. So many programs ended up effectively having the standard command processor embedded, in addition to whatever interface they might themselves support. Though obviously the user had to be careful not to do anything silly like load a new program that overwrote the running program or overwrote their data. Different times.)
- reacweb 12y ago
  On my CPC6128 (Z80), multiplan under CP/M was able to use the full memory (128Ko). In basic, only 64ko were really available.
- adestefan 12y ago
  CP/M abstracted IO operations and allowed you to write applications that where machine agnostic. This was a big deal at the time since there were a large number of BASICs that were incompatible for doing low-level operations. As an example Reddit's /r/retrobattlestations had their annual BASIC week[0] where they take a BASIC program and port it to a bunch of different machines. As you can see they have 11 different versions. [0] https://www.reddit.com/r/retrobattlestations/comments/2fn1zq/basic_week_3_under_the_sea/ https://www.reddit.com/r/retrobattlestations/comments/2fn1zq...

41 points by chl 12y ago

toolslive 12y ago

I think CP/M is where the driver letters in windows came from. Now I know who did it.

Moto7451 12y ago
MS DOS is a clone of CP/M. Since Windows originally ran on top of DOS it inherited the drive letter system.
- MrBuddyCasino 12y ago
  The sources for MS DOS 1.1 and 2.0 are available as well, if you'd like to compare them: http://www.computerhistory.org/atchm/microsoft-ms-dos-early-source-code/ http://www.computerhistory.org/atchm/microsoft-ms-dos-early-...
bodyfour 12y ago
A lot of conventions in CP/M are similar to DEC operating systems of that period (RT-11, RSTS/E, etc) For instance in RT-11 files had the same "device:filename.ext" format. However the device spec was 2-3 characters, not just one letter. There may be earlier antecedents as well.
pjmlp 12y ago
Symbian and Amiga OS also have device names. As for Windows, in the NT line you can also refer to drives via \Devices\... when using object paths in Windows API.

templeos2 12y ago

I have God's endorsement. Go educate yourself on why mine is God's official temple. You will eventually stop being in denial.

Zardoz84 12y ago

And they forgot to put the posterior evolution of CP/M , with the multiuser versions, and later in a compatible "clone of MS-DOS", called DR-DOS.

pervycreeper 12y ago

One thing I never quite understood: in a home computing context, what is the advantage of having a system like CP/M, compared to, say, using a BASIC interpreter which includes the same commands?

nilsimsa 12y ago
The hardware was not quite standardized at that time so CP/M had a layered structure consisting of a BIOS, BDOS and the command line processor. The BIOS was the hardware abstraction layer and was ported to the specific combination of hardware. The BDOS provided the file system and the command line processor provided a standardized interface. On top of this you would run the BASIC interpreter as an application.
- to3m 12y ago
  Right, but while BASIC is running, the command line processor isn't. So if you want to run a command... what then? Presumably the BASIC has to reimplement it. I guess that's the point. Having this layered approach is valuable, but having a separate command processor, perhaps less so. (I never used CP/M but I used to have an Acorn BBC Micro and that had the command line processing built in to the OS, in its equivalent of the BIOS, I suppose to work around this very issue. All an application needed to do was get a string from somewhere, then pass it to the appropriate OS routine. So many programs ended up effectively having the standard command processor embedded, in addition to whatever interface they might themselves support. Though obviously the user had to be careful not to do anything silly like load a new program that overwrote the running program or overwrote their data. Different times.)
reacweb 12y ago
On my CPC6128 (Z80), multiplan under CP/M was able to use the full memory (128Ko). In basic, only 64ko were really available.
adestefan 12y ago
CP/M abstracted IO operations and allowed you to write applications that where machine agnostic. This was a big deal at the time since there were a large number of BASICs that were incompatible for doing low-level operations. As an example Reddit's /r/retrobattlestations had their annual BASIC week[0] where they take a BASIC program and port it to a bunch of different machines. As you can see they have 11 different versions. [0] https://www.reddit.com/r/retrobattlestations/comments/2fn1zq/basic_week_3_under_the_sea/ https://www.reddit.com/r/retrobattlestations/comments/2fn1zq...