Hitachi H8/3048

We have placed this in the 16-bit processor area, however, the 2005 databook1 mentions that the processor could use 16 16-bit registers or 8 32-bit registers. It is too far back to recall which mode we used in the mid 1990s, or what was supported by the toolchain. We cannot even recall if the program was RAM resident or if we did program the on-board ROM.

Looking at archives almost twenty years later, it did not look like much was done in anger — merely flashing the LEDs, programming on-board peripherals and communications down the serial port. The on-board Flash could be programmed via a second on-board processor that acted as the debugger/ low-cost emulator interface.

We bought a Hitachi H8/3048 CISC evaluation board with their PC-based Cygnus GCC port. A serial channel connected to the debugger. It was a pleasure to program. We did some assembly programming and the usual single stepping while examining the registers, however, it was mostly in C.

At the time of the selection, I think they only had the “one time programmable” ZTAT and ROMless versions for sale. The H8/3048 was similar to a 68000. Although the evaluation system was cheap, we never found out what it would cost for an emulator or to reproduce the debug capability on our own boards.

In South Africa, we chose processors from Europe or the USA, as the Japanese companies did not have very good agencies there (sanctions and market too small). Although the H8/3048 worked well and parts were easy to obtain, it unfortunately did not gain much traction with companies we were designing for. The Toshiba 68301 was chosen for a design that was originally going to use the H8/3048, but that also never moved into production. See Toshiba 68301 for more details.

The evaluation system was supported from the Hitachi European design offices. The compilers were free at a time when we paid dearly for 68000 and PowerPC cross-compilers without decent debuggers. Although the H8/3048 was cheap, in the meantime, the 68000 had moved on to the 68040, and RISC had become more attractive. Hitach also had the SuperH RISC families from 1994 that were second sourced by STMicroelectronics.


1   In September, 2011, when we originally created this page, the H8/3048 datasheet was available from Renesas — the Hitachi and NEC microcontroller merger — at
Renesas H8/3048 datasheet (PDF, 878 pages, 5,9MBytes). In June, 2013 it is still at the above link.