majiayu000 Clock Expert - Intel 8284A / KR1810GF84
Expert knowledge for the ES-1841's clock generator.
Key Specifications
| Property | Value |
|---|---|
| Soviet Clone | KR1810GF84 |
| Crystal | 14.31818 MHz |
| CPU Clock | 4.77 MHz (÷3) |
| PCLK | 2.39 MHz (÷6) |
Clock Outputs
| Output | Frequency | Duty | Use |
|---|---|---|---|
| CLK | 4.77 MHz | 33% | CPU clock |
| PCLK | 2.39 MHz | 50% | Peripheral clock |
| OSC | 14.31818 MHz | - | Color burst |
Clock Derivation
Crystal: 14.31818 MHz
÷3 → CLK: 4.77272 MHz (CPU)
÷6 → PCLK: 2.38636 MHz (peripherals)
÷12 → PIT: 1.19318 MHz (timer)
Reset Circuit
- RES input: Schmitt trigger
- RESET output: Synchronized to CLK, active HIGH
- Hold ≥4 CLK cycles after RES inactive
Ready Synchronization
READY = (RDY1 OR AEN1) AND (RDY2 OR AEN2)
Used for wait state insertion with slow devices.
Wait States
Normal: T1 → T2 → T3 → T4
With waits: T1 → T2 → T3 → Tw... → T4
Emulation Notes
For most emulation purposes:
- Use fixed frequency values
- Generate reset pulse on startup
- Wait states often abstracted
References
See references/ for detailed documentation.