HD404369 Datasheet, PDF (95/117 Pages) Hitachi Semiconductor – 4-bit HMCS400-Series microcomputer

HD404369 Series
Programming the Built-In PROM
The MCU’s built-in PROM is programmed in PROM mode. PROM mode is set by pulling RESET, M₀,
and M₁ low, as shown in figure 79. In PROM mode, the MCU does not operate, but it can be programmed
in the same way as any other commercial 27256-type EPROM using a standard PROM programmer and a
100-to-28-pin socket adapter. Recommended PROM programmers and socket adapters are listed in table
29.
Since an HMCS400-series instruction is ten bits long, the HMCS400-series MCU has a built-in conversion
circuit to enable the use of a general-purpose PROM programmer. This circuit splits each instruction into
five lower bits and five upper bits that are read from or written to consecutive addresses. This means that if,
for example, 16 kwords of built-in PROM are to be programmed by a general-purpose PROM programmer,
a 32-kbyte address space ($0000–$7FFF) must be specified.
CE, OE
A₁₄–A₀
O₄–O₀
M₀
M₁
RESET
V_CC
GND
V_PP
HD407A4369
PROM mode pins
Control signals
Address bus
O₇
O₆
O₅
O₄–O₀
O₇–O₀
Data bus
Socket adapter
Figure 79 PROM Mode Connections
V_CC
GND
V_PP
PROM programmer
93