Uploaded March 2025 | Updated September 2026, 2 weeks ago
Going to deep dive into the A1200 RTC Real Time Clock and how it works and why is it not there on the A1200 motherboard even though they laid out the PCB to be able to have it.
Links:
amigadev.elowar.com/read/ADCD_2.1/Hardware_Manual_guide/node00D3.html - page shows that the RTC is just memory mapped (it only has 16 addresses, but 64Kb is allocated in the memory map)
github.com/keirf/amiga-stuff/blob/master/testkit/battclock.c - Amiga Test Kit code to read RTC
amigawiki.org/dnl/schematics/A1200_R1.pdf - Amiga PCB A1200
amiga.de/diary/developers/y2k.html - Amiga Y2K
pureamiga.co.uk/2024/05/14/clock-port-confusion - The Clock Port
Chapters:
0:00 What is a RTC?
0:32 A1200 Motherboard
1:32 Schematic
2:24 RF5C01A RTC Chip
4:47 RTC Chip Registers
5:40 Reading Clock Example
7:54 Year 2079
8:36 Memory Map
10:15 AmigaKit RTC A1200 Module
10:52 More Data Sheets
11:27 The Clock Port
12:30 A500 Schematic (MSM6242 Chip)
13:12 Reading The Chip In 68000 Assembly
Going to deep dive into the A1200 RTC Real Time Clock and how it works and why is it not there on the A1200 motherboard even though they laid out the PCB to be able to have it.
Links:
amigadev.elowar.com/read/ADCD_2.1/Hardware_Manual_guide/node00D3.html - page shows that the RTC is just memory mapped (it only has 16 addresses, but 64Kb is allocated in the memory map)
github.com/keirf/amiga-stuff/blob/master/testkit/battclock.c - Amiga Test Kit code to read RTC
amigawiki.org/dnl/schematics/A1200_R1.pdf - Amiga PCB A1200
amiga.de/diary/developers/y2k.html - Amiga Y2K
pureamiga.co.uk/2024/05/14/clock-port-confusion - The Clock Port
Chapters:
0:00 What is a RTC?
0:32 A1200 Motherboard
1:32 Schematic
2:24 RF5C01A RTC Chip
4:47 RTC Chip Registers
5:40 Reading Clock Example
7:54 Year 2079
8:36 Memory Map
10:15 AmigaKit RTC A1200 Module
10:52 More Data Sheets
11:27 The Clock Port
12:30 A500 Schematic (MSM6242 Chip)
13:12 Reading The Chip In 68000 Assembly
