FRAM71B
User’s Manual
FRAM71B 1.00
- 20 -
©Hans Brueggemann, 2016
11 Using
the
SYSRAM
Feature
The SYSRAM feature allows you to switch between the HP-71B’s operating system in
SYSROM and code that is located in SYSRAM. The following preparation steps are required:
1. Install the desired Operating System in SYSRAM area.
2. Install a modified 4KB RAM module to access the OD signal into Port #1. See chapter
11.2 for instructions on how to modify the module. Soldering skills are required.
1. Set jumpers according to the following table:
Method
Select SYSROM
Select SYSRAM
"Modified Module”
: Jumper installed, : Jumper removed, : Don’t care
Table 3: Jumper Settings for SYSRAM / SYSROM Select
11.1 Some Precautions
v
While using the SYSRAM feature, another peripheral that uses OD must not be plugged
into the HP-71B at the same time.
For example, prior to plugging in the Diagnostic Module, you must "Select SYSROM” accord-
ing to the above table to allow the Diagnostic Module to take over the system.
PORT #1
Module
Module
PORT #1
