VDU-K Interak 1 VDU Interface
| 1A. | (NIOREQ) | (I/O Request) |
| 2A. | NMREQ | Memory Request |
| 3A. | NWDS | Write Data Strobe |
| 4A. | NRDS | Read Data Strobe |
| 5 | AB15 | Address Bus |
| 6 | AB14 | |
| 7 | AB13 | |
| 8 | AB12 | |
| 9 | AB11 | |
| 10 | AB10 | |
| 11 | AB9 | |
| 12 | AB8 | |
| 13 | AB7 | |
| 14 | AB6 | |
| 15 | AB5 | |
| 16 | AB4 | |
| 17 | AB3 | |
| 18 | AB2 | |
| 19 | AB1 | |
| 20 | AB0 | |
| 21 | (NRST) | (Reset) |
| 22 | DB7 | Data Bus |
| 23 | DB6 | |
| 24 | DB5 | |
| 25 | DB4 | |
| 26 | DB3 | |
| 27 | DB2 | |
| 28 | DB1 | |
| 29 | DB0 | |
| 30 | (N1IN) | (Daisy Chain) |
| 31 | (N1OUT) | |
| 32 | NRFSH | Dynamic RAM Refresh |
| 33 | (Ø) | (4.0 MHz Z80A Clock) |
| 34 | (NWAIT) | (Wait State Request) |
| 35 | (+12V) | (Power Supply) |
| 36 | ||
| 37 | Pol | Polarisation Slot |
| 38 | (-12V) | (Power Supply) |
| 39 | ||
| 40A | 0V | Power Supply |
| 41A. | ||
| 42A. | +5V | |
| 43A. |
Signals named in brackets are not used by the card; NRFSH on A32 is used but need not be connected in systems which have no signal on this line. In such circumstances the line should be pulled up to a logic "1" (there is space for a pull-up resistor on the VDU-K card if required). The VDU-K card can be used without modification on ISBUS-A (The Interak 1 bus), KBUS-5, and KBUS-12, (the two variants of KBUS).