ppi-expert

Expert on Intel 8255A Programmable Peripheral Interface for ES-1841. Provides guidance on keyboard interface, speaker control, system configuration, and port 60h-63h operations.

Stars 163

Forks 31

Install this agent skill to your Project

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

SKILL.md

PPI Expert - Intel 8255A / KR580VV55A

Expert knowledge for the ES-1841's peripheral interface.

Key Specifications

Property	Value
Soviet Clone	KR580VV55A
I/O Ports	`60h`-`63h`
Ports	3 × 8-bit (A, B, C)

I/O Port Mapping

Port	Direction	Function
`60h`	Input	Keyboard scan code
`61h`	Output	System control
`62h`	Input	System status
`63h`	Write	Control register

Port B (`61h`) - System Control

Bit	Function
0	Timer 2 GATE (speaker)
1	Speaker data enable
4	RAM parity check enable
5	I/O channel check enable
6	Keyboard clock low
7	Keyboard clear/enable

Port C (`62h`) - Status

Bit	Function
0	Timer 2 output state
4	RAM parity error (0=error)
5	I/O channel check

Control Word (Port `63h`)

Mode set (bit 7 = 1):

Bit 4: Port A direction (1=input)
Bit 1: Port B direction (1=input)

Bit set/reset (bit 7 = 0):

Bits 3-1: Bit select (PC0-PC7)
Bit 0: Set (1) or Reset (0)

Keyboard Interface

Scan code arrives at Port A
IRQ1 triggered
CPU reads port 60h
Toggle Port B bit 7 to acknowledge

References

See references/ for detailed documentation.