AT&T 3B2/300 Technical Reference Manual page 263

FUNCTIONAL D E S C R I P T I O N - - - - - - - - - - - - - - - - - - - - - - - - - - -
VERSION 2 COMPUTER ADDRESS SPECTRUM
STARTING
ADDRESS
DESCRIPTION WIDTH
Ox 00000000 READ ONLY MEMORY (ROM) 32 BITS
Ox 00040000 MEMORY MANAGEMENT UNIT (MMU)
-
Ox 00041000 TIME-OF-DAY CLOCK 8 BITS
Ox 00042000 PROGRAMMABLE INTERVAL TIMER (8253) 8 BITS
Ox 00042010 CLEAR CSR BIT-6 1 BIT
Ox 00043000 NVRAM 4 BITS
Ox 00044000 CONTROL AND STATUS REGISTER (CSR) 16 BITS
Ox 00045000 OMA PAGE REGISTER 1 (HARD DISK)
8 BITS
Ox 00046000 OMA PAGE REGISTER 2 (UART A) 8 BITS
Ox 00047000 OMA PAGE REGISTER 3 (UART B)
8 BITS
Ox 00048000
INTEGRAL OMA CONTROLLER (9517)
8 BITS
Ox 00049000 UARTS (2681) 8 BITS
Ox 00049010 CLEAR UDMA INT.
8 BITS
Ox 0004AOOO INTEGRAL HARD DISK CONTROLLER (2797) 8 BITS
Ox 00048000 RESERVED -
Ox 0004COOO DPDRAM SIZE REGISTER 8 BITS
Ox 00040000 FLOPPY DISK CONTROLLER (2797) 8 BITS
Ox 0004EOOO OMA PAGE REGISTER 4 (FLOPPY) 8 BITS
Ox 0004FOOO RESERVED -
Ox 00200000 FEATURE CARD SLOT 1 16 BITS
Ox 00400000
FEATURE CARD SLOT 2
16 BITS
Ox 00600000 FEATURE CARD SLOT 3 16 BITS
Ox 00800000 FEATURE CARD SLOT 4 16 BITS
Ox OOAOOOOO FEATURE CARD SLOT 5 16 BITS
Ox OOCOOOOO FEATURE CARD SLOT 6 16 BITS
Ox OOEOOOOO
FEATURE CARD SLOT 7 16 BITS
Ox 01000000
FEATURE CARD SLOT 8 16 BITS
Ox 01200000 FEATURE CARD SLOT 9 16 BITS
Ox 01400000 FEATURE CARD SLOT 10 16 BITS
Ox 01600000 FEATURE CARD SLOT 11 16 BITS
Ox 01800000
FEATURE CARD SLOT 12
16 BITS
Ox OlAOOOOO FEATURE CARD SLOT 13 16 BITS
Ox OlCOOOOO
FEATURE CARD SLOT 14 16 BITS
Ox OlEOOOOO FEATURE CARD SLOT 15 16 BITS
Ox 02000000
MAIN MEMORY (DPDRAM) 32 BITS
NOTES:
1. Size depends on which ROM device is used.
2. CSR requires 2 bytes to read, but is bit addressable for writing.
LEGEND:
3. Size depends on size of memory card (256K/1 M/2 M) and
the number of memory cards (1/2).
CSR Control and Status Register
DMA Direct Memory Access
DPDRAM Dual Port Dynamic Random Access Memory
NVRAM Nonvolatile Random Access Memory
UARTS Universal Asynchronous Receiver/Transmitters
Figure 3-3: Version 2 Computer Address Spectrum
3-10 TECHNICAL REFERENCE MANUAL
SIZE
64 KILOBYTES (NOTE 1)
-
16 BYTES
4 BYTES
1 BYTE
1 KILONIBBLE
2 BYTES (NOTE 2)
1 BYTE
1 BYTE
1 BYTE
16 BYTES
16 BYTES
1 BYTE
2 BYTES
-
1 BYTE
4 BYTES
1 BYTE
-
2 MEGABYTES (MAXIMUM)
2 MEGABYTES (MAXIMUM)
2 MEGABYTES (MAXIMUM)
2 MEGABYTES (MAXIMUM)
2 MEGABYTES (MAXIMUM)
2 MEGABYTES (MAXIMUM)
2 MEGABYTES (MAXIMUM)
2 MEGABYTES (MAXIMUM)
2 MEGABYTES (MAXIMUM)
2 MEGABYTES (MAXIMUM)
2 MEGABYTES (MAXIMUM)
2 MEGABYTES (MAXIMUM)
2 MEGABYTES (MAXIMUM)
2 MEGABYTES (MAXIMUM)
2 MEGABYTES (MAXIMUM)
256 KILOBYTES TO
4 MEGABYTES (NOTE 3)