Amiga custom chips

In addition to the Amiga chipsets, various specially designed chips have been used in Commodore Amiga computers that do not belong to the 'Amiga chipset' in a tight sense. CSG 5719 Gary, short for Gate Array, has been used in the Amiga 500, 2000(B) and CDTV. Gary provides glue logic for bus control and houses supporting functions for the floppy disk drive. It integrates many functions built discretely in the earlier Amiga 1000 in order to reduce costs. Fat Gary was Gary's upgrade for the 32-bit A3000/T and A4000/T. Gayle replaced Gary in the A600 and A1200. It also incorporates the control logic for the PCMCIA and internal ATA interface on these systems. Akiko is the CD32's all-purpose 'glue' chip and forms part of the AGA chipset used in that system. Akiko is responsible for implementing system glue logic that in previous Amiga models were found in the discrete chips Budgie, Gayle and the two CIAs. In detail, it includes control logic for the CD32's CD-ROM controller, system timers, the two game ports, the serial ('AUX') port, and the chip memory soldered onto the motherboard. It controls a one kilobyte EEPROM for saving data such as highscores etc. Additionally, the Akiko chip is able to assist simple 'chunky-to-planar' graphics conversion in hardware. The Amiga's native display is a planar display which is simple and efficient to manipulate for routines like scrolling or 2D composition. However, chunky displays are faster and more efficient for 3D graphics manipulation. Akiko assists this conversion in hardware, instead of shifting the bits solely by CPU code which would cause more overhead. The conversion works by writing 32 8-bit chunky pixels to Akiko's registers and reading back eight 32-bit words of converted planar data to be copied to the display buffer. Bridgette is an integrated bus buffer in the A4000 series. It connects the chip, CPU and I/O buses. It replaces six 74F646s and four 74F245s chips used in the original A3000 design. Buster is the expansion BUS conTrollER and was used in the Amiga 2000(B), integrating discrete logic from the original A2000(A).