Turbo Mac Hardware Memory Map

CONFIDENTIAL ------------------------------------------ CONFIDENTIAL TURBO MAC : HARDWARE MEMORY MAP Burrell Smith and Brian Howard 17 October 1984 CONFIDENTIAL ------------------------------------------ CONFIDENTIAL INTRODUCTION Page 1 1. Page 2 Page 3 Page 5 2. THE TURBO MAC ADDRESS SPACE (Overview) 2.1 More Detailed Map of Turbo Mac Address Space 2.2 Address Line Decoding Page 7 3. RAM 3.1 Address Decoding to Activate RAMs Page 8 Page 9 Page 10 3.2 Further RAM Address Decoding 3.3 Some Useful RAM Addresses 3.4 Use of RAM by Hardware 3.4.1 Map of RAM on Power-Up 3.4.2 Normal Map of RAM 3.5 Use of RAM by System and Application Software 3.6 Hardware Exception Vectors Page 11 Page 12 Page 13 Page 14 4. 4.1 4.2 Page 15 Page 16 Page 17 Page 19 Page 20 Page 21 Page 22 Page 23 ROM Address Decoding to Activate ROMs Some Useful ROM Addresses AMU Address Decoding to Activate AMU Further AMU Address Decoding Some Useful AMU Addresses 5.4 Information About AMU Registers 5.4.1 DMA Address Registers 5.4.2 DMA Control Register 5. 5.1 5.2 5.3 6. 6.1 6.2 6.3 DMU Address Decoding to Activate DMU Further DMU Address Decoding Some Useful DMU Addresses 7. RANDOM LOGIC CONTROL (VDXO, VDXl and MISC) 7.1 Address Decoding to Activate Random Logic Control 7.2 Some Useful Random Logic Control Addresses Turbo Mac Memory Map 17 October 1984 Page 24 Page 25 Page 26 Page 27 Page 28 Page 29 Page 30 Page 31 8. SCC 8.1 Address Decoding to Activate SCC 8.2 Further SCC Address Decoding 8.3 Some Useful SCC Addresses 9. IWM 9.1 Address Decoding to Activate IWM 9.2 Further IWM Address Decoding 9.3 Some Useful IWM Addresses 10. VIA 10.1 Address Decoding to Activate VIA 10.2 Further VIA Address Decoding 10.3 Some Useful VIA Addresses 10.4 Turbo-Mac-Specific Information about VIA Registers 10.4.1 Port A Input, Output, and Data Direction Registers 10.4.2 Port B Input, Output, and Data Direction Registers 10.4.3 Control Registers 10.4.4 Interrupt Flag and Enable Registers Page 32 11. AUTO-VECTOR "READ" ADDRESSES Page 33 12. SOME USEFUL DECODING EQUATIONS Previous Document Versions: 1. Page 1 19-5ep-84, 10-Sep-1984. INTRODUCTION The principle portions of Turbo Mac's address space consist of volatile read/write memory (RAM) and permanent read-only memory (ROM). In addition to RAM and ROM, several input/output functions are also selected using address lines, so that they appear to occupy portions of the Turbo Mac "memory". These include the 6522 Versatile Interface Adapter (VIA), the 8530 Serial Communications Chip (SCC), the disk interface chip (IWM), the Address Management Unit (AMU), the Data Management Unit (DMU) , and the Random Logic Control. When the Turbo Mac is first turned on, ROM appears at the bottom (lowest addresses) portion of the address space. This is useful for the ROM-stored software which starts the system running. After startup, the OVERLAY signal from the VIA is changed to a low (zero), mapping RAM into its normal place at the bott…