SCM Apps, Loading Instructions

SCM Apps are programs written to run from the Small Computer Monitor (SCM). Below are detailed instructions on how to load and execute SCM Apps.

The first step is to ensure you have terminal software that reliably communicates with the system running SCM.

RC2014 Classic

Typically, the connection uses a USB to serial adapter with the serial settings:
115200 baud, 8 data bits, 1 stop bit, no parity, RTS/CTS flow control.

One exception is the bit-bang serial port found on some systems, such as SC114. These use a much slower baud rate:
9600 baud, 8 data bits, 1 stop bit, no parity, RTS/CTS flow control.

SC114 with USB to serial adapter and cables

Below is a step-by-step guide to running a typical SCM App. Here we are using Tera Term on Windows 10 with an SC203 system, but any system running SCM, such as standard RC2014 configurations, work the same way.

When the system running and SCM is reset, the terminal should look something like this:

Small Computer Monitor following reset

Select “Send File” from Tera Term’s File menu and locate the App you want to load. In this example, we select the MemTest App for the Z180 processor. The file is named: “SCM_MemTest_Z180_code8000.hex”

If all goes well the display should show “Ready”. You shouldn’t see the contents of the file being displayed in the terminal window. If you do it means SCM has not detected the start of the file.

After an SCM App has been “Sent” from Tera Term

All SCM Apps are filetype “HEX”. A HEX file stores a memory image in Intel HEX format. SCM automatically detects and loads these files.

The program is now in memory but has not yet been executed. Typically, the program code starts at 0x8000. To execute the program, type the command “g 8000”. This means GO to location 8000 hex.

In this case, the program tests memory until a key is pressed.

Executing the SCM App (a memory test program)

This is the method used to load and execute all SCM Apps. The convention is to include the code start address in the filename, but most start at 0x8000.

Other terminal programs may use different terminology, such as “Paste file”. In all cases, the idea is that the HEX file is sent to the SCM system as if its contents had been typed in the terminal window. No fancy file transfer mechanisms are used.

WARNING: It is important to select programs that are compatible with your hardware. There are many different systems available and this means some programs need to be versioned for each.

Homebrew 8-bit retro computing