FRAM71B
User’s Manual
FRAM71B 1.00
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©Hans Brueggemann, 2016
12 FRAM71B-512K-EXT
Memory
Extension
A standard FRAM71B-512 is equipped with a single 512 Kbyte FRAM, referred to as "BOT
FRAM". The FRAM71B-512K-EXT memory extension adds another 512 KB to your FRAM71B
for a total of 1024 KB of FRAM. It is referred to as "TOP-FRAM" and comes pre-installed on
all FRAM71B-1024 modules. See chapter 9 "Memory Configuration" on how to configure
TOP F_Blocks.
Picture 9: FRAM71B-1024 with FRAM71B-512K-EXT installed. Note red jumper on extension
board set to "WRITE ENABLE" position. Remove the jumper to "WRITE PROTECT"
the TOP FRAM.
Three jumpers affect the operation of the TOP FRAM:
12.1 Jumper CN2-1 "SLCT_TOP"
Jumper CN2-1 is located on the FRAM71B main board and controls usage of SYSRAM and
CONFIG area.
If set:
SYSRAM and F_Block 2 of TOP FRAM is selected.
If not set: SYSRAM and F_Block 2 of BOT FRAM is selected (Default setting).
Use this jumper to switch between two different configurations of your HP-71B, including
different operating systems. In order for the FRAM-selection to take effect, the HP-71B has
to be power-cycled. Regardless of CN2-1 setting, all TOP and BOT F_BLOCKs are fully accessi-
ble by both TOP and BOT configurations.
12.2 Jumpers "WRITE ENABLE" and CN2-4 "ENA_SYSRAM_WRITE"
The "WRITE ENABLE” jumper is located on the memory extension board and controls write-
access to TOP FRAM.
If set:
TOP FRAM can be write-accessed (Default setting).
If not set: TOP FRAM is write-protected. This overrides ENA_SYSRAM_WRITE CN2-4.
Use this jumper to hardware-protect the entire TOP FRAM against over-writing. A typical use
case is to first write-enable and "fill" TOP FRAM with desired ROM images and then write-
protect it. Thus, TOP FRAM becomes a "vault” for ROM images, fully protected against acci-
dential misconfigurations in the C_0x2C000 area.
