MK14E Backplane

MK14E Backplane


The MK14E Backplane is a simple 3-slot design which follows the connections on the original MK14 VDU, sockets are on a 1" (25.4mm) pitch.


One important thing to note with regards to the MK14E backplane is that it is not compatible with the Acorn System Backplane.

Not only does the Acorn Backplane have both A32 and B32 joined together (0V) but 0V and +5V are swapped which would be catastrophic !


Pin No. Side A Description Side B Description
1 0V Power 0V +5V Power +5V
2 A0 Lower 12 bits of Address Bus from processor +5V
3 A1 +5V
4 A2 0V Power 0V
5 A3 0V
6 A4 0V
7 A5 EXT I/O Pulling this line disables Mainboard memory and I/O
8 A6 NADS Address Strobe, when low indicates status and upper four address lines are on data bus
9 A7 PB6 8154 (IC4) Port B
10 A8 PB5
11 A9 PB7
12 A10 PB4
13 A11 PB3
14 A12 Upper four Address lines from Latch IC3 PB2
15 A13 PB1
16 A14 PB0
17 A15 PA7 8154 (IC4) Port A
18 D0 Data Bus INTR  
19 D1 PA6 8154 (IC4) Port A
20 D2 PA0
21 D3 PA5
22 D4 PA1
23 D5 PA4
24 D6 PA2
25 D7 PA3
26 NRST System Reset (active low) SENSEA  Sense A condition input to processor can also be used as interupt input
27 XOUT Processor Xtal oscillator output (4MHz) SIN  Serial Input to processor E-register
28 NRDS Read Data Strobe, data read on trailing edge SENSEB  Sense B condition input to processor,
29 NWDS Write Data Strobe, when low indicates valid data on bus SOUT  Serial Output from processor E-register
30 NENOUT High when processor is using the bus FLAG0 Flag 0 output from processor
31 NENIN Enable Input, when low processor can access bus FLAG2 Flag 2 output from processor
32 +5V Power +5V FLAG1 Flag 1 output from processor



Bill Of Materials

Blank PCB

MK14E Backplane PCB



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