SC150 is a 128k byte paged RAM module designed for the RC2014 bus. It is primarily intended to be used with the paged ROM module (SC151). Together these modules provide suitable memory for running CP/M.
- SC150 – Assembly Guide
- SC150 – Firmware (see SC151)
- SC150 – Parts List
- SC150 – Printed Circuit Board
- SC150 – Support
- SC150 – User Guide
Downloads
- SC150, v1.0, Kit contents sheet (PDF)
- SC150, v1.0, Schematic (PDF)
- SC150, v1.0, PCB design files (OSHWLab)
- SC150, v1.0, Gerber files (ZIP)
Suppliers
| Kits | Website | Ships from |
| Stephen C Cousins | Tindie | UK |
| PCBs | Website | Ships from |
| Stephen C Cousins | Tindie | UK |
| Components | Website | Ships from |
| See parts list |
Parts List
| Reference | Qty | Component |
| PCB | 1 | SC150, v1.0, PCB |
| C1 to C3 | 3 | Capacitor, ceramic, 100 nF |
| LED1 | 1 | LED, blue, 3mm |
| P1 | 1 | Header, male, 1 row x 40 pin, angled |
| R1 | 1 | Resistor, 1k, 0.25W |
| U1 | 1 | 74HCT4075 |
| U2 | 1 | 74HCT259 |
| U3 | 1 | RAM 128k bytes AS6C1008 |
| U1 socket | 1 | Socket, DIP, 14-pin |
| U2 socket | 1 | Socket, DIP, 16-pin |
| U3 socket | 1 | Socket, DIP, 32-pin |
Printed Circuit Board
User Guide
SC150 provides 128k of banked RAM together with paging control of the lower 32k. SC151 provides the matching ROM. Together they provide suitable memory for CP/M.
At reset the output bits of integrated circuit U2 are all cleared to zero (low voltage). The ROM is paged into memory from 0x0000 to 0x7FFF (32k bytes) with RAM from 0x8000 to 0xFFFF (32k bytes). When input/output address 0x38 bit 0 is set to one (a high voltage) the ROM is paged out and RAM is paged in, giving a full 64k bytes of RAM from 0x0000 to 0xFFFF.
This module contains 128k bytes of RAM, split into two 64k byte banks. The banks can be swapped with output address 0x30 bit 0. The ROM needs to contain suitable code to swap RAM banks and access them.
The status LED should be ON when the system is in reset. With the recommended firmware, the LED should flash OFF for about half a second when the system is released from reset. It should then turn ON and stay on. User software can then control the LED, as required.
Input/output port functions
| I/O Address | Read | Write |
| 0x08 (0x08 to 0x0B) | n/a | Status LED Low = ON, high = OFF |
| 0x30 (0x30 to 0x33) | n/a | RAM bank select RA16 |
| 0x38 (0x38 to 0x3B) | n/a | Memory paging (lower 32k) Low = ROM, high = RAM |
Jumper options
| Jumper | Function |
| none | n/a |
Assembly Guide
Below is the suggested order of assembly. A general guide to assembling circuit boards can be found here.
- Resistor R1 (1k)
This can be fitted either way around - Sockets for U1, U2 and U3
Fit such that the notch in the socket matches the curve in the outline on the PCB silkscreen - Bus header P1
Make sure the pins are parallel to the PCB so that the board is vertical when it is fitted into a backplane socket - Decoupling capacitors C1, C2 and C3
These can be fitted either way around - Light emitting diode LED1
Fit such that the short lead and/or small flat on the plastic is at the end marked with a line on the PCB silkscreen - Insert the integrated circuits into their sockets
Make sure the notch in the component is at the end indicated by the notch in the socket and the curve on the PCB silkscreen
Notes
- This design is made in accordance with the “designed for RC2014” labelling scheme.
- RC2014 is a trademark of RFC2795 Ltd.
- This product is designed for hobby use and is not suitable for industrial, commercial, or safety-critical applications.
- The product contains small parts and is not suitable for young children.
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