Serial ULA (Ferranti 2C199 / VLSI VC2026 SERPROC) pinout
DIP-28. Baud rate generators for the 6850, switching between cassette and RS423, cassette data separator, tone synthesis and motor control.
Sits between the 6850 ACIA and the outside world. Its control register at &FE10 sets transmit (bits 0-2) and receive (bits 3-5) rates, picks RS423 or cassette (bit 6) and drives the motor relay (bit 7). It needs a 1.23 MHz clock (16 MHz / 13) on pin 25. The pin 15 RC (R75, C28) sets the carrier-detect delay; R75 must suit the chip: 100k or 56k for 2C199E and -3, 82k for 2C199E-7 (SM 6.4). Acorn part 201,648.
Open the interactive SERPROC pinoutPins
| Pin | Name | Type | Signal |
|---|---|---|---|
| 1 | D0 | data | Data bit 0 (control register at &FE10 is write only). |
| 2 | D1 | data | Data bit 1 (control register at &FE10 is write only). |
| 3 | D2 | data | Data bit 2 (control register at &FE10 is write only). |
| 4 | D3 | data | Data bit 3 (control register at &FE10 is write only). |
| 5 | D4 | data | Data bit 4 (control register at &FE10 is write only). |
| 6 | D5 | data | Data bit 5 (control register at &FE10 is write only). |
| 7 | D6 | data | Data bit 6 (control register at &FE10 is write only). |
| 8 | D7 | data | Data bit 7 (control register at &FE10 is write only). |
| 9 | /CS | ctrl | Chip select (SERPROC decode). |
| 10 | E | clock | Enable (bus clock) input. |
| 11 | CASMO | ctrl | Cassette motor: drives Q3 and relay RL1 (and the CAS LED). |
| 12 | CAS IN | audio | Cassette signal from the LM324 filter stages. |
| 13 | DCD | serial | Data carrier detect to the ACIA after the high-tone lead-in. |
| 14 | GND | ground | Ground. |
| 15 | CR | ctrl | Timing RC for carrier detect (Model B: R75 to +5 V, C28 to ground). |
| 16 | DIN | serial | RS423 data in from the line receiver. |
| 17 | RXD | serial | Receive data to the ACIA. |
| 18 | RXC | clock | Receive clock to the ACIA. |
| 19 | CTSO | serial | CTS out to the ACIA /CTS. |
| 20 | CTSI | serial | CTS in from the RS423 receiver (connector pin E). |
| 21 | DOUT | serial | RS423 data out to the line driver. |
| 22 | TXD | serial | Transmit data from the ACIA. |
| 23 | RTSO | serial | RTS out to the RS423 driver (connector pin D). |
| 24 | RTSI | serial | RTS in from the ACIA /RTS. |
| 25 | CLK | clock | 1.23 MHz reference (16 MHz / 13 from a counter, or the Master CHROMA chip by LK14). |
| 26 | TXC | clock | Transmit clock to the ACIA. |
| 27 | CAS OUT | audio | Synthesized cassette tones. |
| 28 | VCC | power | +5 V. |
Fitted in
- BBC Micro Model B IC7
- BBC Master 128 IC48