Retroninja 1541-II Switchless Multi-ROM
A microcontroller based switchless ROM switcher for the Commodore 1541-II disk drive.
Switch between stock CBM DOS, JiffyDOS and other ROMs by issuing commands from Basic.
No computer modifications or drive enclosure modifications needed. Completely reversible drive modification.
Read the user's guide for more information.
A new revision of this board has been released under the more generic name Switchless Multi-ROM for 27128 & 27256
BOM
| Component | Pcs | Name | Comment |
|---|---|---|---|
| SST39SF010A | 1 | IC1 | Flash. SST39SF020/040 should work too. PLCC-32 |
| ATMEGA328P-AU | 1 | IC2 | Or compatible ATmega8/48/88/168/328 variants. TQFP-32 |
| 74AHCT273NSR | 1 | IC4 | Flip-Flop SO-20 (5.3mm width) |
| 74AHCT1G04 | 1 | IC5 | Inverter single gate SOT-23 |
| 100nF ceramic capacitor | 4 | C1, C2, C3, C4 | 0805 |
| 30pF ceramic capacitor | 2 | C5, C6 | 0805 - 22pF works too |
| 10k resistor | 1 | R1 | 0805 |
| 560R resistor | 1 | R2 | 0805 - LED current limiting resistor |
| LED | 1 | D1 | 1206 |
| ECS-160-20-3X-TR | 1 | XTAL1 | Crystal 16MHz |
| 14 pin header | 2 | "IC3" | Male machined pin headers or flat headers. 2.54mm pitch. To fit DIL-28 socket. |
| 6 pin header right-angled | 1 | JP1 | Optional 2.54mm pitch. For ISP programmer. |