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).