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MSM66591/ML66592 User's Manual
Chapter 3 CPU Architecture
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CSR
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(MSM66591)
(ML66592)
3.2.5 Segment Register
The segment register consists of two 8-bit registers: code segment register (CSR) and
table segment register (TSR). It selects a segment in the program memory space.
Since the program memory space of MSM66591 has only two segments, segment 0
and segment 1, only bit 0 is valid for both the CSR and the TSR. Bits 1 to 7 are fixed to
"0".
Since the program memory space of ML66592 has only segments 0, 1 and 2, only bits
0 and 1 are valid for both the CSR and the TSR. Bits 2 to 7 are fixed to "0". (Do not
access segment 3.)
[1]
Code Segment Register (CSR)
CSR specifies the segment in the program memory space to which the program code
being executed belongs. CSR is given as an independent 8-bits register, and is not
assigned to the SFR area.
CSR can be reloaded by the FJ, FCAL, FRT, and RTI instructions and an interrupt. No
other methods can reload CSR. Since in the MSM66591 CSR has only one valid bit
while in the emulator for the MSM66591 CSR has two valid bits, specify either segment
0 or segment 1 when executing the FJ or FCAL instruction for MSM66591.
Since in the ML66592 segment 3 is not provided, specify segment 0, 1 or 2 when
executing the FJ or FCAL instruction (do not access segment 3).
Each segment is assigned offset addresses of 0 through 0FFFFH. The address calcula-
tion for determining the addressing target is performed by a 16-bit offset address, and
the resulting overflow and underflow are ignored, which therefore never results in
change in the CSR. Similarly, a PC overflow never updates the CSR. Therefore, without
the use of the CSR reloading method described above, a program execution does not
progress beyond the code segment boundary. The CSR value at reset is 00H.
When an interrupt is generated after the program memory space is extended to 128K
bytes (MSM66591) or 192K bytes (ML66592), the current CSR value, along with the
PC, is automatically saved onto the stack. Executing the RTI instruction returns the
saved value to CSR. (See Section 3.1.1, "Memory Space Expansion.")
Summary of Contents for ML66592
Page 15: ...Contents 12 ...
Page 17: ......
Page 18: ...Overview Chapter 1 1 ...
Page 19: ......
Page 30: ...Description of Pins Chapter 2 2 ...
Page 31: ......
Page 44: ...CPU Architecture Chapter 3 3 ...
Page 45: ......
Page 101: ...3 56 MSM66591 ML66592User sManual Chapter 3 CPU Architecture ...
Page 102: ...CPU Control Functions Chapter 4 4 ...
Page 103: ......
Page 111: ...4 8 MSM66591 ML66592User sManual Chapter 4 CPU Control Functions ...
Page 112: ...Memory Control Functions Chapter 5 5 ...
Page 113: ......
Page 117: ...5 4 MSM66591 ML66592User sManual Chapter 5 Memory Control Functions ...
Page 118: ...Port Functions Chapter 6 6 ...
Page 119: ......
Page 152: ...Output Pin Control Pin OE Chapter 7 7 ...
Page 153: ......
Page 155: ...7 2 MSM66591 ML66592User sManual Chapter 7 Output Pin Control Pin OE ...
Page 156: ...Clock Generation Circuit Chapter 8 8 ...
Page 157: ......
Page 160: ...Time Base Counter TBC Chapter 9 9 ...
Page 161: ......
Page 164: ...Watchdog Timer WDT Chapter 10 10 ...
Page 165: ......
Page 170: ...Flexible Timer FTM Chapter 11 11 11 ...
Page 171: ......
Page 213: ...11 42 MSM66591 ML66592User sManual Chapter 11 Flexible Timer FTM ...
Page 214: ...General Purpose 8 Bit Timer Function Chapter 12 12 ...
Page 215: ......
Page 223: ...12 8 MSM66591 ML66592User sManual Chapter 12 General Purpose 8 Bit Timer Function ...
Page 224: ...PWM Functions Chapter 13 13 ...
Page 225: ......
Page 244: ...Baud Rate Generator Functions Chapter 14 14 ...
Page 245: ......
Page 263: ...14 18 MSM66591 ML66592User sManual Chapter 14 Baud Rate Generator Functions ...
Page 264: ...Serial Port Functions Chapter 15 15 ...
Page 265: ......
Page 348: ...A D Converter Functions Chapter 16 16 ...
Page 349: ......
Page 381: ...16 32 MSM66591 ML66592User sManual Chapter 16 A D Converter Functions ...
Page 382: ...Transition Detector Functions Chapter 17 17 ...
Page 383: ......
Page 387: ...17 4 MSM66591 ML66592User sManual Chapter 17 Transition Detector Functions ...
Page 388: ...Peripheral Functions Chapter 18 18 ...
Page 389: ......
Page 392: ...External Interrupt Request Function Chapter 19 19 ...
Page 393: ......
Page 396: ...Interrupt Request Processing Function Chapter 20 20 ...
Page 397: ......
Page 407: ...20 10 MSM66591 ML66592User sManual Chapter 20 Interrupt Request Processing Function ...
Page 408: ...Bus Port Functions Chapter 21 21 ...
Page 409: ......
Page 413: ...21 4 MSM66591 ML66592User sManual Chapter 21 Bus Port Functions ...
Page 414: ...Expansion Port Chapter 22 22 ...
Page 415: ......
Page 420: ...Serial Port with FIFO SCI5 Chapter 23 23 ...
Page 421: ......
Page 431: ...23 10 MSM66591 ML66592User sManual Chapter 23 Serial Port with FIFO SCI5 ...
Page 432: ...RAM Monitor Function Chapter 24 24 ...
Page 433: ......
Page 441: ...24 8 MSM66591 ML66592User sManual Chapter 24 RAM Monitor Function ...
Page 442: ...25 Electrical Characteristics Chapter 25 ...
Page 443: ......
Page 458: ...Package Dimensions Chapter 26 26 ...
Page 459: ......
Page 461: ...26 2 MSM66591 ML66592User sManual Chapter 26 Package Dimensions ...
Page 462: ...Revision History Chapter 27 27 ...
Page 463: ......
Page 465: ...27 2 MSM66591 ML66592User sManual Chapter 27 Revision History ...