Register Design for the KITE microprocessor

Register design of the KITE microprocessor

There are seven registers (Instruction register (IR), Accumulator (ACC), Program counter(PC), Index register (IXR), Stack pointer (SP), Address register (AR), Flag register(FR))) in the KITE-1 microprocessor.

3-bus structure

Name Spec. Reset Control 1 Control 2 Control 3 Control 4 Control 5

IR 16 bits Reset control Write control Read control 1 Read control 2 Read control 3 Read control 4

ACC 16 bits Reset Write Read 　　　

PC 12 bits Reset Write Read Inclement 　　

IXR 12 bits Rset Write Read 　　　

SP 12 bits Reset Write Read 　　　

AR 12 bits Set Write 1 Write 2 　　　

FR 4 bits Reset Write 　　　　

Name	Spec.	Reset	Control 1	Control 2	Control 3	Control 4	Control 5
IR	16 bits	Reset control	Write control	Read control 1	Read control 2	Read control 3	Read control 4
ACC	16 bits	Reset	Write	Read
PC	12 bits	Reset	Write	Read	Inclement
IXR	12 bits	Rset	Write	Read
SP	12 bits	Reset	Write	Read
AR	12 bits	Set	Write 1	Write 2
FR	4 bits	Reset	Write

Supplement matters are as the following.

It does the following four reading controls by the reading controls 1, 2, 3, 4 of the control-register.
- It makes 4 bits of higher ranks of the control-register "0000" and it outputs them at bus 1 (the left operand of ALU) (R12).
- It makes 8 bits of higher ranks of the control-register "00000000" and it outputs them at bus 1 (the left operand of ALU) (R8P1).
- It makes 8 bits of higher ranks of the control-register "00000000" and it outputs them at bus 2 (the right operand of ALU) (R8P2).
- It makes 8 bits of higher ranks of the control-register "11111111" and it outputs them at bus 2 (the right operand of ALU) (R8M2).
Controlled Reset makes all contents of the register "0". The set makes all register contents "1".
The reading control is the control signal to output the contents of the register. At the time of "1", at the time of the output, "0", it is in the high impedance condition.
The register (the flag-register, the address register) who doesn't have a reading control is always outputting contents.
INC of the program counter is the control signal to incrementing the contents.
Among the 12-bit register, the connection with the internal bus must connect at 16 bits about IXR, SP, the PC. When writing a value in the register, it writes 12 bits in among 16 bits and in case of the reading, it outputs them at 16 bit of which "0" is 4 bits of higher ranks.
The register who has a reading control, too, has the terminal which does the contents of the register in the continuous output for the following reason.
- The IR has the terminal of the continuous output for the contents to have to be always output beforehand at the decoder sequencer.
- The accumulator, the PC, IXR, SP have the terminal of the continuous output to display contents on the experiment board.

Well, description of register attempts to have.

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