dma-expert

Development

Expert on Intel 8237A DMA Controller for ES-1841. Provides guidance on DMA transfers, floppy/HDD data transfer, DRAM refresh, page registers, and channel configuration.

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Source SKILL.md: https://github.com/majiayu000/claude-skill-registry/blob/HEAD/skills/data/dma-expert/SKILL.md

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DMA Expert - Intel 8237A / KR580VT57

Expert knowledge for the ES-1841's DMA controller.

Key Specifications

Property	Value
Soviet Clone	KR580VT57 / KR1810VT37
Channels	4 independent
I/O Ports	`00h`-`0Fh`
Page Regs	`81h`, `82h`, `83h`, `87h`

I/O Ports

Port	Read	Write
`00h`-`07h`	Current addr/count	Base addr/count
`08h`	Status Register	Command Register
`0Ah`	-	Single Mask Register
`0Bh`	-	Mode Register
`0Ch`	-	Clear Flip-Flop
`0Dh`	Temp Register	Master Clear

Page Registers (Upper 4 Address Bits)

Port	Channel
`87h`	Ch0
`83h`	Ch1
`81h`	Ch2
`82h`	Ch3

Channel Assignments

Channel	Usage
0	DRAM Refresh
2	Floppy Disk
3	Hard Disk

Mode Register (Port `0Bh`)

Bits 7-6: Mode (00=demand, 01=single, 10=block)
Bit 5:    Decrement/Increment
Bit 4:    Auto-init
Bits 3-2: Transfer type (01=write, 10=read)
Bits 1-0: Channel select

Programming Sequence

Mask channel
Clear flip-flop
Write address LSB/MSB
Write page register
Clear flip-flop
Write count LSB/MSB (bytes - 1)
Set mode
Unmask channel

References

See references/ for detailed documentation.