2764-pinout 8K x 8 ROM pinout
DIP-28. 8K x 8 ROM or EPROM in the JEDEC 2764 pinout.
Generic 2764 pinout; the pin text below is the EPROM. ColecoVision (U2): the stock 9464C mask ROM is wired differently (A11, A12 and enable); this map applies only after the WJ4/WJ5 conversion for a 2764. BBC Model B (IC88): the DFS or DNFS EPROM when fitted. HERO 1 (U418): the 8K x 8 monitor ROM (Heath 444-198-1, available only from Heath). It sits at $E000-$FFFF. Jumpers J2, J4 and J6 must be set for the 8K part, and J12 keeps the optional U417 ROM from overlapping. A bad ROM gives a dead robot or a wrong banner. The monitor version must match the drive board. IBM XT 5160 and Portable 5155 (U19): the 8K x 8 ROM sits in a 28-pin socket wired like the 32K socket U18 (XT Technical Reference 1502237 sheet 5 of 10): pins 1 and 27 carry A14 and pin 26 carries A13, which an 8K part does not use.
Open the interactive 2764 ROM pinoutPins
| Pin | Name | Type | Signal |
|---|---|---|---|
| 1 | VPP | power | Programming voltage. Tie to Vcc in normal use. |
| 2 | A12 | addr | Address bit 12. |
| 3 | A7 | addr | Address bit 7. |
| 4 | A6 | addr | Address bit 6. |
| 5 | A5 | addr | Address bit 5. |
| 6 | A4 | addr | Address bit 4. |
| 7 | A3 | addr | Address bit 3. |
| 8 | A2 | addr | Address bit 2. |
| 9 | A1 | addr | Address bit 1. |
| 10 | A0 | addr | Address bit 0. |
| 11 | D0 | data | Data bit 0. |
| 12 | D1 | data | Data bit 1. |
| 13 | D2 | data | Data bit 2. |
| 14 | GND | ground | Ground. |
| 15 | D3 | data | Data bit 3. |
| 16 | D4 | data | Data bit 4. |
| 17 | D5 | data | Data bit 5. |
| 18 | D6 | data | Data bit 6. |
| 19 | D7 | data | Data bit 7. |
| 20 | /CE | ctrl | Chip enable, active low. |
| 21 | A10 | addr | Address bit 10. |
| 22 | /OE | ctrl | Output enable, active low. |
| 23 | A11 | addr | Address bit 11. |
| 24 | A9 | addr | Address bit 9. |
| 25 | A8 | addr | Address bit 8. |
| 26 | NC | nc | No connection on the 2764. (A13 on the 27128 and larger parts.) |
| 27 | /PGM | ctrl | Program pulse. Not used in reading; tie high. |
| 28 | VCC | power | +5 V supply. |
Fitted in
- HERO 1 U418
- ColecoVision U2 only after the EPROM conversion (solder traces cut, jumpers WJ4/WJ5 fitted). A stock board has the 9464C mask ROM, whose pins 2, 20 and 23 differ: see 9464C.
- IBM XT 5160 U19, the 8K x 8 ROM in the second 28-pin socket (Technical Reference: one socket holds 32K, the other 8K). 6359116 on the photographed board
- IBM Portable 5155 U19, the 8K x 8 ROM (as on the XT). 6359116 on the photographed board
- BBC Micro Model B IC88 (8K DFS/DNFS EPROM when fitted)