Driver:INTELLEC 4

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INTELLEC® 4/MOD 40

The INTELLEC 4/40 is an Intel MCS-40 (4004/4040) development system with interactive debugging features. MAME provides built-in artwork showing the state of front panel LEDs and switches. All switches are clickable. Due to the large number of switches and potential clashes with keys used for typing monitor commands into the terminal, most switches don't have keys assigned by default. However, a few switches do have keyboard mappings.

Front Panel LEDs

  • STATUS LEDs:
    • SEARCH COMPLETE indicates that the selected address has been accessed the desired number of times and the display is frozen
    • RUN indicates that the CPU is running (i.e. not currently acknowledging stop/halt condition)
    • POINTER VALID indicates that a SRC instruction has been detected since the last time search mode was entered and the LAST RAM/ROM POINTER LEDs are valid
  • MODE LEDs: indicates the currently selected program storage - MONitor ROM, RAM card, or PROM card
  • ADDRESS LEDs: show the opcode address accessed by the CPU, or the selected address in CMA mode
  • INSTRUCTION LEDs: show the opcode accessed by the CPU, or data at the selected address in CMA mode
  • EXECUTION LEDs: show the data on the bus during the X2 and X3 instruction phases (X2 is the value read/written for I/O instructions)
  • ACTIVE BANK LEDs: show the state of the CM-RAM chip select signals during the A3 instruction phase
  • LAST RAM/ROM POINTER LEDs: shows the address output by the most recent SRC instruction

Mode Selection

The INTELLEC 4/40 has three 4KiB program storage spaces: onboard monitor PROM, 4KiB console RAM, and PROM space. The onboard monitor PROM uses 1KiB of its 4KiB space. It's possible to install universal cards that place code in the other 3KiB, but it's practically useless because the monitor provides no way to read or jump to such code. There's nothing in the PROM space by default, but universal cards can map code here.

Pressing any of the three MODE CONTROL switches, MON, RAM or PROM, selects the respective program storage space and resets the CPU (4040) and memory controller (4289). Execution will start from address zero in the selected storage space. The front panel search/capture state is also reset, and universal cards may respond to the CPU reset signal.

The MODE CONTROL switches are all momentary, and are mapped to keypad 1 (MON), keypad 2 (RAM) and keypad 3 (PROM) by default. Pressing two MODE CONTROL switches at once will result in no program storage being mapped (the CPU will execute from unmapped reads).

Stop/Run/Single Step/Halt

Turning the STOP switch on stops the CPU, and turning it off allows the CPU to run. While the STOP switch is on, pressing the SINGLE STEP switch allows the CPU to run for a single instruction and then stops it again, allowing you to step the program one instruction at a time. By default, the STOP button is mapped to the keyboard left arrow, and the SINGLE STEP switch is mapped to the keyboard right arrow. The STOP toggles, and the SINGLE STEP switch is momentary.

If the running program stops the CPU with a HLT instruction, you can resume it from the front panel by turning the STOP switch on and then off again. Universal cards can also stop the CPU, there is no way to override this from the front panel. The RUN LED will be turned off for stop/halt conditions caused by the STOP switch, universal cards requesting stop, or the HLT instruction.

If the front panel display is not frozen and CMA mode is not selected (SEARCH COMPLETE LED off and CMA switch set to DISABLE), the ADDRESS LEDs will show the address of the next instruction to be executed, and the INSTRUCTION LEDs will show the opcode (M1 = OPR, M2 = OPA). Note that this is the next instruction that will be executed after the the CPU resumes, not the last instruction executed before the CPU stopped.

CMA Mode

Console Memory Access (CMA) mode allows you to examine/edit the 4KiB of onboard program storage RAM using the front panel switches. To use CMA mode, flip the CMA switch to ENABLE (this is a toggle switch). In CMA mode, the ADDRESS LEDs always show the currently selected address, and the INSTRUCTION LEDs show the current data at the selected address in RAM.

To set the selected address, enter it in binary on the twelve ADDRESS/DATA switches (up = 1, down = 0), and press the LOAD switch (mapped to keypad enter by default). You can also decrement or increment the selected address by one with the DECR and INCR switches (mapped to keypad minus and keypad plus by default, respectively). The ADDRESS/DATA switches are all toggles, while the DECR, INCR and LOAD switches are momentary.

To change a value in RAM, first ensure CMA mode is enabled and the desired address has been selected. Enter the desired value on ADDRESS/DATA switches 7-0 (the eight rightmost ADDRESS/DATA switches, up = 1, down = 0), and press the CMA WRITE switch (momentary, mapped to keypad slash by default). The INSTRUCTION LEDs will update to reflect the new value.

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