Questions tagged [c]
For questions regarding the use or installation of the C language on retrocomputers.
58
questions
7
votes
0answers
170 views
Which pre-ANSI C compilers allowed a ternary expression as Lvalue?
Soon after learning the C language in the late 80s, before an ANSI C compiler was available on the machines I was using, it occurred to me to check if the following compiles
int a, b, c;
foo() {
(...
1
vote
1answer
276 views
Did DEMOS have a C compiler?
DEMOS was a Soviet operating system derived from BSD Unix. The answer to this question shows that the familiar, English-derived BSD commands were essentially the same in DEMOS.
Did DEMOS have a C ...
2
votes
1answer
241 views
Microsoft C 6, far pointer, cast to int, warning C4047
Trying to access one byte in memory using segment/offset, like this
union REGS in, out;
struct SEGS segs;
int v;
char _far* p;
...
int86x(...,&in,&out,&segs);
p = (segs.es << 16) + ...
26
votes
1answer
4k views
Where is the ancient preprocessor?
I found the old C compiler from V6, and, though it seems to the modern eye a little different from good, idiomatic C, evidently it uses things like #include and #define, but I do not see how it ...
1
vote
1answer
203 views
When did cross-platform C start assuming function prototypes? [closed]
The most important difference between the original 'K&R' C, and ANSI/ISO C89/90, was function prototypes. These started being supported by some compilers in the mid-eighties, were formally ...
35
votes
6answers
5k views
Why is this gcd implementation from the 80s so complicated?
First of all, I hope this is the right place to post this question. I was looking through one of my dad's old programming books from the 80s, and at the back it has a list of utility functions, one of ...
30
votes
3answers
4k views
Why is the ‘auto’ storage class specifier included in C?
The auto keyword in C seems quite redundant: wherever it makes sense to define a variable with automatic storage duration, it is already the default, so there is no reason to use the keyword. The ...
13
votes
2answers
1k views
How would I reliably detect the amount of RAM, including Fast RAM?
If I was to write an Amiga game, what would be the best/most reliable way to detect how much RAM is actually available?
Looking at Action's Guide to AGA-Fixing!, he mentions Faulty Memory Detection:
...
7
votes
2answers
493 views
Labels in cc65 inline assembler with #define macro
In general, it is possible to use inline assembler statements within C macros, for example
#define toscreencode(C) (__AX__ = (C), \
asm("cmp #$60"),\
...
11
votes
3answers
2k views
Is this the reason why fread/fwrite has 2 `size_t` arguments?
It just came to me that, the C standard I/O functions fread and fwrite are having 2 size_t arguments because of I guess possibly, that on some systems, there may be more memory of which whose size can ...
19
votes
10answers
7k views
When if ever was the C language 'int' size altered from the host machine word (register) size into a literal 32 bit size?
From the earliest K&R reference manuals I read, 'int' was synonymous with machine word and it seemed to raise adverse reactions in various user domains. With the UNIX crowd, they minimally ...
2
votes
2answers
210 views
Why isn't this invocation of XMS function Move EMB 0Bh in Turbo C correct?
Following on from my last question, I cannot get Move Extended Memory Block (Function 0Bh) working in Turbo C 2.01.
The following main.c contains only the minimum functions: get the XMS driver pointer,...
4
votes
2answers
486 views
How can I malloc() a block that's guaranteed to lie within a single DMA segment in Turbo C 2.01?
I'm following root42's videos about DOS programming using Turbo C 2.01. I've written my own Soundblaster 1.xx driver following the Creative Labs documentation, and I'm confused about memory allocation....
0
votes
3answers
271 views
Should C be regarded as an Intermediate Language? [closed]
Should C be regarded as an intermediate language on a virtual machine named PDP-11 Architecture (which have a plain memory space and stacks), like opcode to jvm, msil to dotnet, asm.js to v8, which ...
2
votes
0answers
172 views
Hitting the CMS Limits of Portable Code
I wrote this arbitrary precision arithmetic utility on BSD in my postgraduate days, then after graduating ported it to DOS using TurboC. Was proud that it would do the same thing with 16bit word ...
1
vote
1answer
191 views
Working on programming a retro z80 computer (SDCC error)
I am working on coding a driver of sorts for a Z80 based computer I am making. I am compiling with SDCC and I have been getting the following?
ASlink-Warning-Undefined Global 'data' referenced by ...
2
votes
2answers
320 views
How to implement a 'write' function in pdp-11 / MACRO-11 / ODT using simh?
So, I'm working on a project where I'm aiming to get the first winner of the IOCCC (obfuscated c code contest) dissected down to the last detail... The program is mullender.c which you can find by ...
5
votes
1answer
276 views
What is the format of the static libraries shipping with legacy Microsoft C for DOS?
I have installed Microsoft C 5.10 on DOS 6.22. It created a 'LIB' directory with static libraries to link against. Now I need to extract the symbols and the code for the functions from them, but can't ...
0
votes
1answer
258 views
Do any of the open source Sinclair ZX Spectrum emulators support both TR-DOS and 3DOS?
The number of Spectrum emulators has been growing for decades now so there's quite a lot for different platforms and written in different languages.
I'm interesting in learning about two of the disk ...
6
votes
4answers
501 views
C/C++ UI library similar to Visual Basic for DOS
I'm looking for a UI library that offers a similar "experience" to that provided by Microsoft's infamous, Visual Basic for DOS RAD environment.
I mean, it's such a compelling environment, ...
0
votes
4answers
342 views
What is the earliest implementation of the stack data structure in C? [closed]
I am trying to find the source code for the earliest implementation of the stack data structure in C, but I can't find anything.
I am particularly interested in knowing if the member variables of the ...
8
votes
4answers
2k views
Imaging a HDD from DOS over Serial
I have recently fixed an old IBM Clone, which has an MFM hard drive. The PC booted up fine, but then I saw, that a few years back, I have deleted a few important files (probably by mistake). The ...
4
votes
2answers
383 views
ZX Spectrum scroll waiting for user input problem
I'm trying to compile a C program with z88dk for the ZX Spectrum. Using printf(), when the text hits the bottom line of the screen on line 24 the program stops executing until a key is pressed on the ...
4
votes
5answers
664 views
Z88DK ZX Spectrum “%f” printf not working
I'm attempting to compile a program in C for the ZX Spectrum using Z88DK.
However, I'm facing an issue when trying to use printf to print out the value of a float.
The code I'm trying to compile:
#...
13
votes
3answers
1k views
Memory models for assembly libraries for Turbo C
Turbo C follows the Intel Memory Model where in Tiny, Small and Compact models calling a function is near but in Medium, Large and Huge models calling a function uses far calls.
If I want to develop ...
6
votes
2answers
320 views
Why isn't the 'restrict' keyword useful in SDCC when compiling for Z80 target? [closed]
Context
SDCC claims to support C11.
I use it to write games on Z80 target (for fun and experience).
C11 defines restrict
C11 specifies the restrict keyword on pointers, which can improve generated ...
17
votes
0answers
794 views
Oxford C compiler for Commodore 64
I kept one floppy from my Commodore 128 (which I used mostly in C64 mode), labelled ‘Oxford C compiler’. It is a 5.25″ floppy. Don't ask me why I kept just this one; probably because I thought I ...
11
votes
1answer
705 views
cprintf printing invisible characters in C program on VIC 20
I want to compile and run a Hello World program in C with the cc65 compiler for an unexpanded VIC-20 model. For printing I'm using the conio.h function cprintf, since the conio implementation requires ...
30
votes
1answer
3k views
Did DOS zero out the BSS area when it loaded a program?
As an example, say we have a DOS MZ EXE file that's around 20 KiB in size. The EXE header contains the value 0x1400 at offset 0x0A indicating that the program is requesting 5,120 paragraphs (or 80 KiB)...
29
votes
9answers
10k views
How did early x86 BIOS programmers manage to program full blown TUIs given very few bytes of ROM/EPROM?
I've always wondered how so much functionality and relative luxuries(CMOS Configuration Utilities. See: https://geekprank.com/bios/ for an example) included with most popular x86 BIOSes could be ...
6
votes
3answers
801 views
Why is modulo operation an operator for integer types but only a function for floating-point ones?
In C, we have the % operator which finds remainder of division. But it's only applicable to integral types. For floating-point types we have to use fmod function from math.h. This makes an impression ...
29
votes
3answers
8k views
Was Dennis Ritchie being too modest in this quote about C and Pascal?
In his 1993 conference proceeding The Development of the C Language, Dennis Ritchie stated
Successors
C and even B have several direct descendants, though they do not rival Pascal in ...
64
votes
5answers
14k views
Why did C use the -> operator instead of reusing the . operator?
In the C programming language, the syntax to access the member of a structure is
structure.member
However, a member of a structure referenced by a pointer is written as
pointer->member
...
10
votes
3answers
3k views
DOS, create pipe for stdin/stdout of command.com(or 4dos.com) in C or Batch?
I'm working on a retro project and was trying to create a pipe of stdin/out/err in DOS, but I can't find any functions to to this?
For instance the pipe() command from unistd.h isn't present in ...
1
vote
2answers
133 views
DOS, create pipe for stdin/stdout of command.com(or 4dos.com) in C or Batch? [duplicate]
I'm working on a retro project and was trying to create a pipe of stdin/out/err in DOS, but I can't find any functions to to this?
For instance the pipe() command from unistd.h isn't present in ...
11
votes
9answers
1k views
Alternatives for TurboVision on DOS
TurboVision was a library by Borland for developing TUI's (Text User Interfaces). It was included with their C++ and Pascal compilers.
Were there any other TUI libraries that supported multiple ...
87
votes
20answers
18k views
Have programming languages driven hardware development?
Programming language development has been influenced by hardware design. One example from this answer mentions how C pointers were, at least in part, influenced by the design of the PDP-11. Has the ...
5
votes
3answers
1k views
Were some Atari 2600 games written in C?
I thought all Atari 2600 games had been programmed in 6502/6507 assembly language (plus whatever activated the Stella sound system), but at a party recently, a friend indicated that some 2600 ...
3
votes
1answer
436 views
How to read disk files using CBM specific functions in cc65 with proper error checking
TL:DR
What is the reason my kernel_read() function ignoring file errors?
I'm trying to understand how to work with files in cc65 using CBM specific functions. My target is Commodore 64 with 1541 ...
4
votes
3answers
898 views
Allocate 64 KiB in Watcom C 16-bit DOS
I'm trying to allocate a 64 KiB buffer in Watcom C 16-bit DOS. I'm using the "compact" memory model which defines the code segment to be limited to 64 KiB and addressed by near pointers (...
-3
votes
2answers
945 views
gcc: installation problem, cannot exec 'as': No such file or directory
How do I compile my code that I have typed on my SGI Indy computer? I have already tried to install the GCC/G++ compilers, but when I run my application, I get the error that says:
gcc: ...
1
vote
1answer
475 views
How do I compile C code with the IRIX X Window System?
I have typed out a rather large file in C code that is defining OpenGL graphics and will draw a triangle on the screen. While I know all of the functions of the X Windowing System, I do not know how ...
3
votes
4answers
732 views
Was there ever a compiler type that was just large enough to contain a memory segment?
From this answer,
Hark back to the days of segmented 16-bit architectures for example: an array might be limited to a single segment (so a 16-bit size_t would do) BUT you could have multiple ...
19
votes
6answers
4k views
What caused the downfall of Pascal? [closed]
From 1985 to 1990 Borland's Turbo Pascal was at least as popular as C for DOS systems. Turbo Pascal was especially popular because of it's ground breaking BGI graphics interface while C was stalled in ...
9
votes
1answer
1k views
What was the name of the object-oriented C language I used in the 1980s on the Mac
I clearly recall working with an object-oriented C derivative on the Mac but I cannot find any definitive references to it.
It was back in the days of System 7 and later System 8. It had both ...
33
votes
2answers
5k views
Why was UNIX never backported to the PDP-7?
Originally, UNIX was written in PDP-7 assembly, and then in PDP-11 assembly, but then when UNIX V4 began to be re-written in C in 1973 and was run mostly on the PDP-11.
So far as I can tell, there ...
84
votes
8answers
33k views
Why do C to Z80 compilers produce poor code?
When reading some other questions about compiling C for the Z80,
How much benefit should be expected on a more advanced compiler for z80/r800 based computers?
Native C compiler for Sinclair ZX ...
15
votes
3answers
5k views
Native C compiler for Sinclair ZX Spectrum
I am looking for a native C compiler for the Spectrum 128. I would like one which:
Has good support for the latest C standard at the time.
Is not limited to compiling ridiculously short source code.
...
46
votes
5answers
15k views
Why did C have the return type before functions?
In general, there are two types of syntax of defining functions - Something like C, C++, C#, or Java (int functionName(char arg)) vs the ML (and others) tradition of defining the return type after the ...
41
votes
7answers
9k views
The history of the NULL pointer
As we know, in C to dereference a null pointer is undefined behaviour. From what I understand, the PDP-7 and the PDP-11 both have ordinary memory that can be written to and read from at address 0.
On ...
