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IA2910A_08 参数 Datasheet PDF下载

IA2910A_08图片预览
型号: IA2910A_08
PDF下载: 下载PDF文件 查看货源
内容描述: 微控制器 [Microprogram Controller]
分类和应用: 微控制器
文件页数/大小: 21 页 / 681 K
品牌: INNOVASIC [ INNOVASIC, INC ]
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IA2910A  
Data Sheet  
Microprogram Controller  
August 19, 2008  
Functional Overview  
The IA2910A is a 0.8 µm CMOS microprogram controller intended for use in high-speed  
microprocessor applications. It allows addressing of up to 4K words of microprogram.  
The controller contains a four-input mux that is used to select either the register/counter, direct data  
input, microprogram counter, or stack as the source of the next microinstruction address.  
The register/counter consists of 12 D-type, edge-triggered flip-flops, with a common clock enable.  
When its load control, RLDn, is LOW, new data is loaded on a positive clock transition. A few  
instructions include load; in most systems, these instructions will be sufficient, simplifying the  
microcode. The output of the register/counter is available to the mux as a source for the next  
microinstruction address. The direct input furnishes a source of data for loading the  
register/counter.  
The IA2910A contains a microprogram counter that is composed of a 12-bit incrementer followed  
by a 12-bit register. The counter can be used in either of two ways. When the carry-in to the  
incrementer is HIGH, the microprogram register is loaded on the next clock cycle with the current  
YOUT output word plus one. Sequential microinstructions are thus executed. When the carry-in is  
LOW, the incrementer passes the YOUT output word unmodified so that the counter is reloaded  
with the same YOUT word on the next clock cycle. The same microinstruction is thus executed any  
number of times.  
The third source for the mux is the direct DIN input. This source is used for branching.  
The fourth source available at the mux input is a 9-word by 12-bit stack (file). The stack is used to  
provide return address linkage when executing microsubroutines or loops. The stack contains a  
built-in stack pointer (SP) which always points to the last file word written. This allows stack  
reference operations (looping) to be performed without a pop.  
The stack pointer operates as an up/down counter. During microinstructions 1, 4, and 5, the PUSH  
operation may occur. This causes the stack pointer to increment and the file to be written with the  
required return linkage. On the cycle following the PUSH, the return data is at the new location  
pointed to by the stack pointer.  
During five microinstructions, a POP operation may occur. The stack pointer decrements at the  
next rising clock edge following a POP, effectively removing old information from the top of the  
stack.  
The stack pointer linkage is such that any sequence of pushes, pops, or stack references can be  
achieved. At RESET (Instruction 0), the depth of nesting becomes zero. For each PUSH, the  
nesting depth increases by one; for each POP, the depth decreases by one. The depth can grow to  
nine. After a depth of nine is reached, FULLn goes LOW. Any further PUSHes onto a full stack  
overwrite information at the top of the stack, but leave the stack pointer unchanged. This operation  
will usually destroy useful information and is normally avoided. A POP from an empty stack may  
place non-meaningful data on the YOUT outputs, but is otherwise safe. The stack pointer remains  
at zero whenever a POP is attempted from a stack already empty.  
IA211030314-03  
http://www.Innovasic.com  
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