# ZX Spectrum ULA

Can be found at Sinclair ZX Spectrum's, I think

(At the computer)

UNKNOWN CONNECTOR at the computer.

Pin | Name | Description
--- | --- | ---
1 |  |
2 | /WR | Write
3 | /RD | Read
4 | /WE | Write Enable
5 | A0 | Address 0
6 | A1 | Address 1
7 | A2 | Address 2
8 | A3 | Address 3
9 | A4 | Address 4
10 | A5 | Address 5
11 | A6 | Address 6
12 | /INT | Interrupt
13 | +5V | +5 VDC (One of the +5V is decoupled through a RC-low-pass.)
14 | +5V | +5 VDC (One of the +5V is decoupled through a RC-low-pass.)
15 | U | Color-difference signals.
16 | V | Color-difference signals.
17 | /Y | Inverted Video+Sync.
18 | D0 | Data 0
19 | T0 | Keyboard Data 0
20 | T1 | Keyboard Data 1
21 | D1 | Data 1
22 | D2 | Data 2
23 | T2 | Keyboard Data 2
24 | T3 | Keyboard Data 3
25 | D3 | Data 3
26 | T4 | Keyboard Data 4
27 | D4 | Data 4
28 | SOUND | Analog-I/O-line for beep, save and load.
29 | D5 | Data 5
30 | D6 | Data 6
31 | D7 | Data 7
32 | CLOCK | The clock-source to the CPU including the inhibited T-states.
33 | /IO-ULA | (A0(CPU) OR /IORQ) for the I/O-port FEh
34 | /ROM CS | ROM ChipSelect
35 | /RAS | Row Address Strobe
36 | A14 | Address 14
37 | A15 | Address 15
38 | /MREQ | ???
39 | Q | The 14 MHz crystal. Other side grounded through capacitor.
40 |  |