
Operating Registers
SYM53C810A Data Manual
5-33
Register 39 (B9)
DMA Interrupt Enable (DIEN)
Read/Write
T his register contains the interrupt mask bits corre-
sponding to the interrupting conditions described
in the DST AT register. An interrupt is masked by
clearing the appropriate mask bit. Masking an in-
terrupt prevents IRQ/ from being asserted for the
corresponding interrupt, but the status bit will still
be set in the DST AT register. Masking an interrupt
will not prevent the IST AT DIP from being set. All
DMA interrupts are considered fatal, therefore
SCRIPT S will stop running when a DMA interrupt
occurs, whether or not the interrupt is masked. Set-
ting a mask bit enables the assertion of IRQ/ for the
corresponding interrupt. (A masked non-fatal in-
terrupt will not prevent un-masked or fatal inter-
rupts from getting through; interrupt stacking
begins when either the IST AT SIP or DIP bit is
set.)
T he SYM53C810A IRQ/ output is latched; once
asserted, it will remain asserted until the interrupt
is cleared by reading the appropriate status register.
Masking an interrupt after the IRQ/ output is as-
serted will not cause IRQ/ to be deasserted.
For more information on interrupts, see Chapter
T wo, “Functional Description.”
Bit 7
Reserved
Bit 6
MDPE (Master Data Parity E rror)
Bit 5
BF (Bus fault)
Bit 4
ABRT (Aborted)
Bit 3
SSI (Single step interrupt)
Bit 2
SIR (SCRIPT S interrupt
instruction received
Bit 1
Reserved
Bit 0
IID (Illegal instruction detected)
Register 3A (BA)
Scratch Byte Register (SBR)
Read/Write
T his is a general purpose register. Apart from CPU
access, only Register Read/Write and Memory
Moves into this register will alter its contents. T he
default value of this register is zero. T his register
was called the DMA Watchdog T imer on previous
SYM53C8X X family products.
RES
7
MDPE
6
BF
5
ABRT
4
SSI
3
SIR
2
RES
1
IID
0
Default>>>
X
0
0
0
0
0
X
0