Agent skill

cpu-expert

Expert on K1810VM86 (Intel 8086) CPU architecture for ES-1841. Provides guidance on registers, instruction decoding, memory segmentation, interrupts, bus cycles, and x86-16 behavior.

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Install this agent skill to your Project

npx add-skill https://github.com/majiayu000/claude-skill-registry/tree/main/skills/data/cpu-expert

SKILL.md

CPU Expert - K1810VM86 / Intel 8086

Expert knowledge for the ES-1841's central processor.

Key Specifications

Property Value
Soviet Clone K1810VM86
Architecture x86-16, 16-bit data, 20-bit address
Clock 5 MHz (ES-1841)
Reset Vector FFFF:0000 → Physical FFFF0h

Register Set

General Purpose (16-bit, split into 8-bit):

  • AX (AH/AL) - Accumulator
  • BX (BH/BL) - Base
  • CX (CH/CL) - Count
  • DX (DH/DL) - Data

Index/Pointer: SI, DI, BP, SP

Segment: CS, DS, SS, ES (reset: CS=FFFFh, others=0000h)

Special: IP, FLAGS

Memory Segmentation

text
Physical Address = (Segment << 4) + Offset

1 MB address space. Key regions:

  • 00000h-003FFh - IVT
  • 00400h-004FFh - BIOS Data Area
  • B8000h-BFFFFh - Video RAM
  • F0000h-FFFFFh - System BIOS

FLAGS Register

Bit Flag Function
0 CF Carry
2 PF Parity
4 AF Auxiliary Carry
6 ZF Zero
7 SF Sign
8 TF Trap (single-step)
9 IF Interrupt Enable
10 DF Direction
11 OF Overflow

Interrupt Handling

  1. Complete current instruction
  2. Push FLAGS, CS, IP
  3. Clear IF and TF
  4. Load CS:IP from IVT[vector × 4]

Bus Cycles

4 clocks per memory/IO access (minimum mode):

  • T1: Address, ALE high
  • T2: ALE low, RD/WR asserted
  • T3: Data transfer
  • T4: Bus idle

References

See references/ for detailed documentation.

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