Apple II Plus
Applesoft in ROM.
Open the Apple II Plus in Retro Bench- Also
- Apple ][+
- Year
- 1979
- CPU
- 6502 @ 1.02 MHz
- RAM
- 48 KB (4116)
- ROM
- Applesoft + Monitor
- Video
- Discrete TTL + 2513 character ROM: 40-col text, lo-res, hi-res
- Sound
- 1-bit speaker
- OS
- Applesoft BASIC, DOS 3.3 (optional)
Chips
| Chip | Where | Role |
|---|---|---|
| 6502 / 65C02 CPU | CPU | |
| 4116 DRAM 16K x 1 | Dynamic RAM, 16K x 1 (lower 16K on the Spectrum) | |
| 9316B / 2316B ROM 2K x 8 | 2K x 8 mask ROM: Apple II monitor and BASIC ROMs; TRS-80 ROM C and character generator | |
| MM5740 Keyboard Encoder | Keyboard PCB | Keyboard encoder (early II and II+) |
Ports and connectors
- Power supply to main board, 6-pin AMP 9-35028-1 header (supply cable plugs in)
- Game I/O (16-pin DIP socket, J14), 16-pin DIP socket
- Peripheral slots 0-7 (50-pin edge), 50-pin card edge, 0.10 in pitch (Winchester 2HW25C0-111)
- Video out (RCA), RCA phono jack
- Auxiliary video connector (4-pin), Molex KK100, 4 square pins on 0.10 in
- Cassette IN, 3.5 mm mono jack
- Cassette OUT, 3.5 mm mono jack
- Keyboard connector (16-pin DIP socket), 16-pin DIP socket
- Speaker connector (2-pin), Molex KK100, 2 square pins on 0.10 in
Power rails
| Rail | Expect | Measure at |
|---|---|---|
| +5 V | 4.85-5.15 V (Red Book p. 111) | 6502 pin 8; 9316B pin 24; ii-psu pin 3 (PSU connector); ii-slot pin 25 |
| +12 V | 11.3-12.3 V (Red Book p. 111) | 4116 pin 8; ii-psu pin 4 (PSU connector); ii-slot pin 50 |
| -5 V | -4.7 to -5.7 V (Red Book p. 111) | 4116 pin 1; ii-psu pin 6 (PSU connector); ii-slot pin 34 |
| -12 V | -11 to -13 V (Red Book p. 111) | ii-psu pin 5 (PSU connector); ii-slot pin 33; MM5740 pin 18 |
Symptoms
- No beep / dead machine: check 6502, 9316B
- Garbage or no boot: check 4116, 9316B
- No video
- Dead keys: check MM5740
- Power supply clicks or squeals