HD404618 Datasheet, PDF (70/91 Pages) Hitachi Semiconductor – 4-Bit Single-Chip Microcomputer

HD404618 Series
Programming the Built-in PROM
The MCU’s built-in PROM is programmed in PROM mode which is set by pulling TEST, M₀, and M₁ low,
and RESET high, as shown in figure 43. In PROM mode, the MCU does not operate, but it can be
programmed in the same way as any other commercial 27256 EPROM using a standard PROM
programmer and a 80-to-28-pin socket adaptor. Recommended PROM programmers and socket adapters
are listed in table 34.
Since an HMCS400-series instruction is ten bits long, the HMCS400-series MCU has a built-in conversion
circuit to enable use of a general-purpose PROM programmer. This circuit splits each instruction into a
lower 5 bits and an upper 5 bits that are read from or written to consecutive addresse. This means that if,
for example, 8 kwords of built-in PROM are to be programmed by a general-purpose PROM programmer,
a 16-kbyte address space ($0000–$3FFF) must be specified.
Programming and Verification: The built-in PROM of the MCU can be programmed at high-speed
programming sequence without risk of voltage stress or damage to data reliability.
For details of PROM programming, refer to the notes on PROM Programming section.
Warnings
1. Always specify addresses $0000 to $3FFF when programming with a PROM programmer. If address
$4000 or higher is accessed, the PROM may not be programmed or verified correctly. Set all data in
unused addresses to $FF.
Note that the plastic-package version cannot be erased and reprogrammed.
2. Make sure that the PROM programmer, socket adapter, and LSI are aligned correctly (their pin 1
positions match), otherwise overcurrents may damage the LSI. Before starting programming, make
sure that the LSI is firmly fixed in the socket adapter and the socket adapter is firmly fixed onto the
programmer.
3. PROM programmers have two voltages (V_pp): 12.5 V and 21 V. Remember that ZTAT™ devices
require a V_PP of 12.5 V—the 21-V setting will damage them. 12.5 V is the Intel’s 27256 setting.
Table 33 PROM Mode Selection
Pin
Mode
CE
OE
V_PP
Programming
Low
High
V_PP
Verification
High
Low
V_PP
Programming inhibition High
High
V_PP
O₀–O₇
Data input
Data output
High impedance
68