Hardware manual

Rev. 3.0, 09/98, page 257 of 361
14.3 Programming
The write, verify, and other sub-modes of the PROM mode are selected as shown in table 14.4.
Table 14.4 Selection of Sub-Modes in PROM Mode
Sub-Mode CE OE PGM V
PP
V
CC
EO
7
to EO
0
EA
16
to EA
0
Write Low High Low V
PP
V
CC
Data input Address input
Verify Low Low High V
PP
V
CC
Data output Address input
Programming
inhibited
Low
Low
High
High
Low
High
Low
High
Low
High
Low
High
V
PP
V
CC
High impedance Address input
Note: The V
PP
and V
CC
pins must be held at the V
PP
and V
CC
voltage levels.
The H8/338 or H8/337 PROM has the same standard read/write specifications as the HN27C101
EPROM. Page programming is not supported, however, so do not select page programming
mode. PROM writers that provide only page programming cannot be used. When selecting a
PROM writer, check that it supports the byte-at-a-time high-speed programming mode. Be sure to
set the address range to H'0000 to H'BFFF for the H8/338, and to H'0000 to H'7FFF for the
H8/337.
14.3.1 Writing and Verifying
An efficient, high-speed programming procedure can be used to write and verify PROM data.
This procedure writes data quickly without subjecting the chip to voltage stress and without
sacrificing data reliability. It leaves the data H'FF written in unused addresses.
Figure 14.5 shows the basic high-speed programming flowchart.
Tables 14.5 and 14.6 list the electrical characteristics of the chip in the PROM mode. Figure 14.6
shows a write/verify timing chart.