Michael Steil

Aus der Homecomputer- und frühen Personal-Computer-Zeit sind Disketten nicht wegzudenken. Dieser Vortrag beschäftigt sich mit Diskettentechnologie am Beispiel des 5,25-Zoll-Laufwerks "Commodore 1541", bekannt als das Laufwerk zum Commodore C64. Nach einer historischen Einordnung (Bänder, Platten, 8-Zoll-Disketten) besprechen wir den Aufbau von Laufwerken und Disketten, sowie das Low-Level-Aufzeichnungsformat (Spuren, Sektoren, SYNC-Marker, GCR-Codierung) und dessen Implementierung in der Laufwerks-Firmware. Danach behandeln wir das Dateisystem-Format und die Datenübertragung zwischen dem Laufwerk und dem C64. Wir thematisieren außerdem Schnelllader, welche die Laufwerks-Firmware durch optimierteren Code zum Lesen und zur Datenübertragung ersetzen, sowie Kopierschutz-Systeme, die Nonstandard-Formate mit verschleierten Leseroutinen verbinden. Schließlich sprechen wir noch über Lösungen zum fehlerfreien Auslesen von antiken Disketten mit moderner Hardware.

The Apollo Guidance Computer ("AGC") was used onboard the Apollo spacecraft to support the Apollo moon landings between 1969 and 1972. This talk explains "everything about the AGC", including its quirky but clever hardware design, its revolutionary OS, and how its software allowed humans to reach and explore the moon.

The AGC was an early digital computer specifically designed for the Apollo moon missions. The Command Module and the Lunar Module each contained one AGC. First built in 1965 from 5600 integrated circuits, it was one of the first minicomputers, beating commercial machines like the PDP-8 in weight (32 kg) and power consumption (55 W). The Apollo program's size and weight limitations as well as the requirements for real-time guidance, navigation and control were pushing 1960s technologies to their limits. As a 15 bit one's complement big-endian accumulator machine with 36 kilo-words of ROM and 2 kilo-words of RAM, its design seems very foreign from today's perspective. The operating system was real-time, priority-based cooperative/preemptive and fault-tolerant, supporting interpreted virtual machines – practically inventing many of these concepts. This talk explains all the hardware details of the AGC: Its machine language, counters, timers, I/O, display and keyboard, as well as its implementation using integrated circuits, core memory and "core rope" ROM. The talk goes on to explain the software: interrupt handling, the core set, the wait list, the alarm system, the interpreter, and the actual user software, providing, among other things, guidance, navigation and control (GNC) services. The audience will get a good understanding of hardware and software design in the 1960s, and appreciate the innovations driven by the Apollo program.

Other people: Christian Hessmann

The 8-bit Game Boy was sold between 1989 and 2003, but its architecture more closely resembles machines from the early 1980s, like the Commodore 64 or the NES. This talk attempts to communicate "everything about the Game Boy" to the listener, including its internals and quirks, as well as the tricks that have been used by games and modern demos, reviving once more the spirit of times when programmers counted clock cycles and hardware limitations were seen as a challenge.

The Nintendo Game Boy was an 8-bit handheld gaming console that competed with the SEGA Game Gear and the Atari Lynx. Compared to its competition, it had very little RAM (8 KB) and no color support (4 shades of gray at 160x144). It was succeeded by the Game Boy Color, which fixed this main shortcoming, but shared the same architecture. During the 14 year life span of the 8 bit Game Boy platform, game programmers kept understanding the hardware better and better, and continued finding new tricks for better graphics effects, such as sprite multiplexing, parallax and palette effects. This talk explains all the hardware details of the Game Boy: The programming model of the 8080/Z80-like LR35902 CPU, the system's sound, timer and I/O functionality, and programming details as well as common tricks involving the graphics processor ("PPU"), which was specifically designed for LCD output. The listener will get a good understanding of 8 bit programming and creative programming on extremely limited hardware, as well as common tricks that can be generalized to other systems.