Though fork() bombs were one way people could still screw up and kill systems…. Unix and other more commercial or bigger system OSes had hardware support for memory protection and could offer true multitasking from the get go, though of course some dialects of Unix would drop that if the hardware didn’t support it.īut Unix/Linux/Minix/etc all really didn’t take off until the advent of the Intel 386 with memory protection support built into the chip, which made them much much much more robust for running multiple processes at the same time and not having quite as much chance of bringing everything to a screeching halt if something crapped all over memory. The AmigaOS was one of the early consumer OSes to support this, though it was cooperative multitasking, since programs could still stomp all over memory if they weren’t careful. But this just show how most early desktop computers were quite limited due to the OS not really supporting multitasking at all. One of the early Borland succeses was sidekick, an early TSR (Terminate and Stay Resident) program which let you run your main application, but then hit a hotkey to get into Sidekick to take notes, run a calculator, etc. Well, back in the day when you played a game on an Apple ][ it was even simpler because the AppleOS did all the disk controlling, the drives were quite dumb. Posted in Raspberry Pi Tagged cpm, free pascal, raspberry pi, retrocomputing, ultibo, z80 Post navigation If you’d rather go old school, you could try reproducing the Rum 80. We’ve covered other bare-metal projects in the past. That’s all you really need to make your own emulator or write your own Doom clone. You can see a video about Ultibo (the first of a series) below. Ultibo is still very much in active development, but the most common functions are already there you can write to the framebuffer, read USB keyboards, and write to a serial port. The choice of Free Pascal will delight some and annoy others, depending on your predilections. The secret to this development is an open source system known as Ultibo, a framework based on Open Pascal which allows you to create bare metal applications for the Raspberry Pi. Unlike the significant boot times of the standard Linux distros on the earliest models of Pi, you can boot into CP/M in just five seconds. It’s available for the Raspberry Pi Model B, A+, and the Raspberry Pi 2 Model B. The files reside on an SD card and the Pi directly boots it, avoiding any Linux OS (like Raspian). If you want to try booting a “bare metal” Z80 emulator with CP/M on a Raspberry Pi, you can try EMUZ80 RPI. However, as a practical matter, retrocomptuters break, and with emulation, you’d assume that CPU cycles spent on the host operating system (and other programs running in the background) will take away from the target retrocomputer. Part of it is just aesthetics, and of course the real retrocomputing happens on retro hardware. However, there’s something attractive about avoiding booting a modern operating system and then emulating an older system on top of it. Retrocomputing is an enjoyable and educational pursuit and - of course - there are a variety of emulators that can let you use and program a slew of old computers.
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