Product Description:

The E4809-045-035-A is a main controller card designated MB0 in the E4809 CNC Boards series from Okuma. Installed in the base slot of an OSP numerical control, this main board forms the processing hub for spindle, axis, and operator tasks in an industrial lathe or machining center. Its role is to manage CPU instruction flow, direct memory access transfers, real-time clock ticks, the programmable timer module, and volatile memory so that motion sequences and HMI routines remain synchronized. Because it sits in the base slot, other CNC boards depend on it for address management and coordinated access to shared backplane resources.

The board supports bubble memory up to 16 Mbits, and its volatile storage peaks at 0.5 Mbytes, with a factory-loaded bank of 128 Kbytes for basic operating variables. Bubble cartridges plug into the dedicated window at FFDFC0-FFDFFF, while the processor sees program and data objects in the contiguous main space 000000-07FFFF. Each figure is an absolute address range on the dual-bus backplane, so the CNC kernel can issue byte-accurate fetches without bank-switching delays. That layout keeps application code, system tables, and service data in fixed locations during operation. Address decoding logic inside the board maps these regions and arbitrates DMA bursts between motion interrupts.

Expansion is limited to supported bubble capacities of 128 Kbytes and 1, 2, or 4 Mbits and removable RAM options of 128 or 384 Kbytes. General I/O tasks exchange status bytes through the main I/O region FFDD00-FFDE1F, while background diagnostics use the SVP window at F80000-F87FFF and the timing circuits remain isolated in FA8000-FAFFFF for deterministic cycle marks. The narrower main core span of FFDF00-FFDF9F helps keep supervisory registers separate from user code. Separating the I/O, diagnostic, and timing areas also reduces contention between routine status traffic and time-sensitive control activity.