Questions tagged [cp-m]
For questions related to the CP/M operating system by Gary Kildall.
65
questions
2
votes
3
answers
514
views
Z80 to 68000 translator for CP/M
CP/M was mostly portable across systems but most of them were z80 based. It was ported to 8086, 68000 and maybe more but without binary compatibility.
No z80 systems that wanted CP/M compatibility ...
- 1,239
13
votes
4
answers
2k
views
In CP/M, how did a program know when to load a particular overlay?
Here is what I understand so far:
A program that was too large to put into main memory was broken into several overlay regions. Once you needed data from outside of the currently loaded region, ...
- 3,141
20
votes
1
answer
1k
views
Are any CP/M systems still in commercial use today?
I understand that there is a great deal of mainframe-era enterprise software that is still in active use, if not on the original hardware then in emulated environments. Its users keep it running ...
- 7,023
4
votes
1
answer
229
views
Was the S-83 Personal CP/M CPU used in commercial computers?
The June 1984 edition of Practical Computing magazine (page 43) refers to the American Microsystems Incorporated S-83 CPU as a Z80 compatible CPU with an 8K mask ROM capable of holding Digital ...
- 20.5k
0
votes
1
answer
137
views
Is there a digital version of the CP/M T/Maker manual available?
I have a CP/M emulator running on a Raspberry Pi. I managed to run the old circa 1979 T/Maker program, but I don't have a manual. Any thoughts on where I can find one?
6
votes
2
answers
548
views
CONIN (Console In) in CP/M and "old characters" in character latch
CP/M uses CONIN to read a single character from the keyboard, and it will assert CONST to poll the status register for incoming characters. Let's assume the keyboard controller can buffer one ...
- 819
9
votes
1
answer
335
views
What was FDOS an abbreviation for in CP/M?
Digital Research wrote in the CP/M manual that
"The BIOS and BDOS are logically combined into a single module with a common entry point and referred to as the FDOS. "
What is FDOS an ...
- 819
8
votes
4
answers
1k
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 ...
- 819
2
votes
1
answer
195
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 ...
- 819
13
votes
3
answers
2k
views
How many characters/pages could WordStar hold on a typical CP/M machine?
I was looking at the Atari Word Processor which could hold only about one or two pages in 48k memory due to it requiring DOS to be loaded along with the relatively large program itself.
That led me to ...
- 19.5k
8
votes
2
answers
555
views
Is there any known magic number signature for CP/M-80 program files?
I'm looking for a way to identify CP/M-80 (i.e. 8080 code) program files (.COM) from their content. A process usually known as Magic Number or File Signature detection, intended to identify a file by ...
- 213k
7
votes
1
answer
421
views
Why didn't the CP/M-86 assembler support traditional macros?
The ASM86.CMD assembler Digital Research shipped with CP/M-86 provided only code-macros, a limited type of macros for creating new instructions through a small set of specific directives. Why didn't ...
- 1,313
5
votes
0
answers
212
views
How many CP/M-86 copies were sold?
Approximately how many CP/M-86 copies or licenses did Digital Research sell across the product life of the operating system? Are there any data or estimates?
I know the success of MS-DOS didn't leave ...
- 1,313
21
votes
3
answers
2k
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 ...
- 38.2k
5
votes
1
answer
702
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 ...
- 819
15
votes
3
answers
2k
views
Running CP/M on my own Intel 8080 emulator
I recently finished writing an emulator for the Intel 8080, having passed all of the usual test suites, and wanted to try running an actual OS on it (such as CP/M). I'm aware that I would have to ...
- 161
6
votes
1
answer
468
views
How do I read a port value using Turbo Pascal inline code on CP/M?
After successfully using port[0] to read a port value in Turbo Pascal, I thought I'd try to understand how to do this using inline assembly/machine code.
I'm able to write to the port (my OutPort ...
- 819
11
votes
5
answers
2k
views
Early implementations of the `system()` call in a consumer OS
Nowadays, it's easy to take for granted the system() call (as defined in POSIX), which allows a user program to easily execute a child process and wait for it to complete. Obviously, this is a trivial ...
- 60.1k
14
votes
1
answer
4k
views
Good Z80 disassembler/decompiler on modern equipment?
I have a hobby project with an old CP/M-80 system, where I now would like to disassemble/decompile some compiled code – a ROM and some small executables – into assembly source so I can regenerate the ...
- 2,097
16
votes
2
answers
880
views
What was special about "Vulcan" - the CP/M database program?
The Vulcan DBMS for CP/M micros was originally developed in 8080 assembly language by a contractor working for Jet Propulsion Lab, based on an earlier JPL mainframe program. This code went on to be ...
- 60.1k
6
votes
3
answers
998
views
Z80, best way to page out EEPROM
Trying to design a Z80 based computer that starts from an EEPROM, loads CP/M to RAM and pages out (switches off) EEPROM to allow CP/M to access full 64K RAM. What is a good way of achieving this ? My ...
- 381
11
votes
1
answer
555
views
Assembler where output file was executable WHILE including the source code
I seem to remember using an assembler with the following interesting workflow: You'd write an assembly language file and assemble it. The output overwrote your source code by placing the executable ...
- 6,119
4
votes
2
answers
295
views
Replacing an 8" disk drive with a newer/smaller drive on an old 8-bit computer?
I used to have an out-phased Danish 8-bit computer as a hobby machine back in the 90's. It had two external 8" floppy drives, and I have kept the old floppies. Now I'd like to salvage my old ...
- 2,097
13
votes
1
answer
1k
views
When did the Altair move ROM to the top of memory?
The 8080 starts running code at location 0 on reset. The natural layout of memory on a computer using that CPU is therefore ROM at the bottom of the memory map and RAM at the top.
CP/M demands the ...
- 58.4k
7
votes
1
answer
481
views
Did OSes write the floppy's logical sector number resulting from sector interleave/skew in the IDAM sector ID, or was it up to the OS?
I've been looking at MicroBee floppy disk image files. They use the DSK/EDSK image file format originally created for Amstrad CPC emulators, probably because both systems use derivatives of the CP/M 2....
- 6,333
12
votes
1
answer
2k
views
How to quit MBASIC and return to CP/M?
I've tried everything I can think of. EXIT QUIT END STOP BYE Q…
- 2,230
3
votes
2
answers
193
views
Is there a "most correct" name for the disk format / filesystem used by Amstrads and Spectrum +3's?
The native floppy disk format/layout or "filesystem" used by Amstrad microcomputers such as the CPC and PCW range and by the Sinclair Spectrum +3 are versions of one that came from CP/M.
In Amstrad ...
- 6,333
1
vote
1
answer
299
views
How does the Spectrum +3 know how many files are in the disk's directory?
The Spectrum+3 uses a version of the Amstrad and CP/M disk layout.
The Speccy version has a directory at the start of the disk after any reserved tracks and it can hold up to 64 files.
Each ...
- 6,333
15
votes
3
answers
2k
views
Are there games for the C128 that run (mainly) on the Z80 rather than the 6502?
The Commodore 128 was a version of the Commodore 64 that also had a Z80 CPU along with its "native" 6502 CPU so the system could run CP/M as well as C64 software. (As well as more RAM and ...
- 6,333
22
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 ...
- 60.1k
26
votes
4
answers
5k
views
What was the intention with the Commodore 128?
The Commodore 128 had 2 CPUs, 2 video graphic chips, and 2 I/O systems/chips.
It had 3 modes: Commodore 64 mode, Commodore 128 mode and CP/M. The first shared one of each CPU/chip, the CP/M mode the ...
- 973
4
votes
2
answers
612
views
What was the format for .OBJ files produced by M80.COM for CP/M?
When DOS released in 1981, the assembler that came with it produced .OBJ files that were OMF format. However there was a predecessor to it, M80.COM that ran under CP/M and also used .OBJ as the file ...
- 277
2
votes
1
answer
194
views
Reserving extra directory blocks with cpmtools?
I'm trying to create a boot disk for the Kaypro II (from scratch). I've been using cpmtools to generate file system images for other platforms, mostly with success.
However, the Kaypro II has this ...
- 1,290
7
votes
1
answer
414
views
How to get BBC BASIC to TRS-80?
I recently discovered there's BBC BASIC for CP/M machines. Having had my fill of Microsoft Basic, I need to get BBC BASIC onto a disk I can boot on a TRS-80 Model 4P.
I have no CP/M disk (or image) ...
- 60.1k
7
votes
3
answers
1k
views
How to get a plain text file version of a CP/M .BAS (M-BASIC) program?
I have an old game (STRTRK.BAS) from my dad's Kaypro 10 that I would like to convert to a plain text file. Basically, what I'm trying to do is get it onto a modern computer in plain text format so I ...
- 331
12
votes
5
answers
2k
views
Are all CP/M-80 implementations binary compatible?
I never was into CP/M, but I knew it was very popular and the amount of software out there was significant. That being said, when you looked beyond the Kaypros, the IMSAIs, the SOLs and the like which ...
- 15.8k
12
votes
3
answers
2k
views
Did CP/M support custom hardware using device drivers?
MS DOS Ver 1.0 did not have OS support for device drivers. DOS ver2 added support for device drivers in the config.sys file during boot with the "DEVICE=[path][filename][parameters]".
Did CP/M have ...
- 4,469
13
votes
2
answers
831
views
Are there any known viruses for CP/M?
Are there any (known) viruses for CP/M? Chronologically, CP/M machines fit into the time period of the first home computer viruses, starting with other 8-bit computers.
Given the hardware ...
- 4,953
1
vote
1
answer
272
views
How viable is a universal PC parallel/serial connected CP/M disk controller/drive?
I had an idea and wanted to hear if there are any major technical obstacles.
Imagine any vintage computer with either a serial port or a parallel port.
The vintage computer is connected via that ...
- 457
14
votes
1
answer
1k
views
In CP/M, how does control-Z (hex 1a decimal 26) not interfere with ordinary file storage?
Consider this - I have made a file called test.bin on a Windows machine. It is exactly 256 bytes long, and contains nothing more than 00 to ff in each byte.
What would happen if I transferred this ...
- 457
8
votes
2
answers
1k
views
IBM would-be purchase of CP/M
It is well-known that on a sunny day in 1980, when the IBM representatives came knocking on the door of Digital Research, Gary Kildall was still in the air on the way back from visiting another ...
- 58.4k
6
votes
2
answers
714
views
CP/M SKU per CPU only?
The impression I get is that CP/M relied on the BIOS, provided in ROM with the computer, for all the hardware-specific functions. So if you bought CP/M, you didn't have to specify what computer you ...
- 58.4k
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 ...
- 58.4k
6
votes
3
answers
2k
views
Can a Harlequin ZX Spectrum clone be modifed to run CP/M?
The ZX Spectrum (and therefore the Harlequin) has its ROM from $0000 to $3FFF, while RAM further up to $5AFF is used for the screen (see Memory-Map). As CP/M expects RAM from $0000 upwards the two are ...
- 840
8
votes
2
answers
2k
views
What is the meaning of M in the Z80 statement ADD A,M
Recently I have been trying to compile CP/M 2.2 from source. When I try to assemble, everything works except for the instructions ADD A,M and SBC A,M, which the assembler returns a syntax error. I ...
- 81
12
votes
5
answers
2k
views
What was the most popular CP/M terminal type?
I'm porting CP/M to a new/old machine (the Amstrad NC200 laptop). Running programs on it is no problem, but running interesting programs (i.e. WordStar, Turbo Pascal and Ladder) involves implementing ...
- 1,290
9
votes
4
answers
2k
views
Purpose of two disk drives on the Osborne 1
I recently discovered the Osborne 1 computer, and I noticed it had two floppy disc drives.
What was the purpose of including two drives?
user11265
2
votes
3
answers
506
views
Was parsing or operating systems the first user of dollar sign as end of string/input?
According to the question Why did DOS use dollar-terminated strings? DOS uses dollar-terminated strings, inherited from CP/M which used them because DEC also used dollar as the string terminator.
...
- 963
8
votes
2
answers
877
views
How big was WordStar 1.0?
How big was the original CP/M version of WordStar? As in, the size of the program itself? Presumably it was in the low tens of kilobytes (I don't think it's possible to cram a practical word processor ...
- 58.4k
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,...
- 58.4k