Agent skill
ram-expert
Expert on RAM subsystem for ES-1841. Provides guidance on memory map, DRAM refresh, parity checking, conventional memory layout, and BIOS data area.
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/ram-expert
SKILL.md
RAM Expert
Expert knowledge for the ES-1841's memory subsystem.
Key Specifications
| Property | Value |
|---|---|
| Type | DRAM with parity |
| Capacity | 128 KB - 640 KB |
| Width | 8 data + 1 parity bit |
| Refresh | DMA Ch0 + PIT Ch1 |
Memory Map
| Address Range | Size | Description |
|---|---|---|
00000h-003FFh |
1 KB | Interrupt Vectors |
00400h-004FFh |
256 B | BIOS Data Area |
00500h-9FFFFh |
~640 KB | Conventional RAM |
A0000h-BFFFFh |
128 KB | Video RAM |
C0000h-DFFFFh |
128 KB | ROM Extensions |
F0000h-FFFFFh |
64 KB | System BIOS |
BIOS Data Area (BDA)
| Offset | Size | Description |
|---|---|---|
0400 |
8 | COM port addresses |
0408 |
8 | LPT port addresses |
0413 |
2 | Memory size (KB) |
0417 |
2 | Keyboard flags |
046C |
4 | Timer tick count |
DRAM Refresh
PIT Ch1 triggers DMA Ch0 every ~15 µs:
- Prevents data loss in DRAM
- Count = 18 at 1.19 MHz ≈ 15 µs
Parity Checking
- 9th bit per byte (odd parity)
- Error triggers NMI
- Port
61hbit 4: Enable check - Port
62hbit 7: Error flag
References
See references/ for detailed documentation.
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