Macintosh LC 575 Developer Note

The Macintosh LC 575 Computer Developer Note is Apple's 1994 hardware description of the Macintosh LC 575, published by Apple's Developer Press for developers of compatible hardware and software. The hosted file is an 86-page PDF produced in March 1995. It covers the machine's features, architecture, ROM and system software, expansion slot and internal storage bays, with an appendix on the AppleCD 300i Plus drive. It is not a repair manual.

Contents

• Preface: About This Note (p. ix)
• Chapter 1, Introduction (p. 1): features and Table 1-1, comparison with the LC 520 and LC 475 (pp. 2-3); design, logic board access, built-in display, front-panel buttons, power on and off, Power Saver (pp. 3-7); RAM expansion and SIMM signals (pp. 7-11); video RAM (p. 12); SCSI bus and termination (pp. 13-15); floppy drive (p. 15); serial ports (p. 16); communications options (p. 17); ADB (p. 17); sound (pp. 18-20); keyboard, reset and NMI (p. 20); expansion slot (p. 21)
• Chapter 2, Architecture (p. 23): block diagram, 68LC040, custom ICs MEMCjr, PrimeTime, DFAC II, Cuda and Antelope (pp. 24-28); address maps (p. 28); video display parameters (p. 30)
• Chapter 3, Software (p. 33): ROM software and machine identification (p. 34); system software, control panels and screen driver (pp. 36-41)
• Chapter 4, Expansion (p. 45): slot pin assignments and signals (pp. 46-50); compatibility with older cards (p. 51); expansion card design and power (pp. 51-53)
• Chapter 5, Internal Storage Devices (p. 55): slide-in bays and internal CD-ROM drive, including its power budget (pp. 56-61)
• Appendix: AppleCD 300i Plus (p. 63); Index (p. 65); foldouts (p. 69)

What it settles

• Design: the LC 520's case and display with the LC 475's electrical design; Table 1-1 compares the three machines (pp. 2-3).
• Processor: 68LC040 at 33 MHz with no FPU; 1 MB ROM soldered to the logic board (p. 2).
• RAM: 4 MB on the board and one 72-pin SIMM socket for 1 to 32 MB SIMMs of 80 ns or faster, 36 MB in all (pp. 7-8). The Service Source asks for 100 ns or faster.
• VRAM: two 68-pin sockets and no VRAM on the board; both sockets must hold SIMMs of the same size, 256 KB or 512 KB each, for 512 KB or 1 MB (p. 12).
• Communications slot: a socket for one of three cards (modem, Ethernet with AUI, or Ethernet with 10BASE-T); Apple states it is not an expansion connector (p. 17).
• Expansion slot: the LC 475's slot, taking 96-pin LC II cards and 114-pin LC III and LC 520 cards, not connected directly to the processor (p. 21). A card may draw 800 mA at +5 V, 20 mA at −5 V and 200 mA at +12 V, 4 W in all (p. 52).
• SCSI: the internal hard disk terminates the internal end of the bus (p. 14).
• CD-ROM power: 500 mA at +5 V and 800 mA at +12 V, 1.5 A peak (p. 60).
• Machine identification: gestaltMachineType 92 ($5C) (p. 34).

What it does not contain

No schematic, no component values and no parts list; nothing on the analog board, power supply voltages, CRT adjustments or the PRAM battery. For service procedures see Macintosh LC 520/550/575 Service Source. Apple's engineering schematic and bills of materials for the logic board are hosted separately as File:LC575.pdf.

Pages that cite this document

• Macintosh LC 575 (specifications, memory, VRAM, communications and expansion slots, custom ICs)

Download: Macintosh LC 575 Developer Note.pdf (950 KB)