alt Hacker News> My recollection is that most CP/M programs were configured via patching. At least that’s how I configured them. I remember my WordStar manual coming with details about which bytes to patch to do what. There was also a few dozen bytes of patch space set aside for you to write your own subroutines, in case you needed to add custom support for your printer.
Huh. That is interesting, it was before my time, and I never heard of this :D
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> > My recollection is that most CP/M programs were configured via patching.
> Huh. That is interesting, it was before my time, and I never heard of this :D
Yep, it was a thing, and for /some/ programs that were originally CP/M programs (i.e., WordStar 7.0 for DOS) it continued for a long time. The WordStar 7 documentation included patch locations to use (this time, IIRC, for DOS debug.exe) to change various behaviors of the program.
Some sort of still do. The stuff that suckless writes is generally configured by changing config.h and recompiling.
Edit: oops just saw that this was already mentioned in another subthread on this page.
That is interesting, it was before my time, and I never heard of this
It was necessary because both RAM and disk space were so severely limited, and because almost every computer came with an assembler.
Many CP/M programs were expected to run in as little as 32K RAM, and 130K of slow-ass floppy disk. Or worse – From a cassette tape. If you had 64K of RAM and a 360K disk, you were something special.
Unlike today, most programs were optimized for the bottom of the market, not the top. You wanted your program to run on as many system as possible so you could sell more copies. You didn't just shrug your shoulders and tell people to upgrade their hardware. The failure was yours, not your customers'.
There simply wasn't room for any kind of external configuration file, or a program to generate that configuration file. Common functions could be accessed via a command-line parameter, but even that logic eats valuable bytes.
Today people complain about the MacBook Neo having just 8,000,000,000 bytes of RAM, saying you can't do anything in such a limited space.
Meanwhile, in 1978, people could write an entire rudimentary IDE in 2,048 bytes.
Yes, it was definitely a thing. The patching code had to be in Z80/8080 machine code. I wrote higher performance keyboard and display routines for my copy of Wordstar using this feature.