Playing with HP2640B

Wed Nov 15 18:25:19 CST 2017

is there a  dif  between  40 a  and  40  b   with the firmware/loader/etc?  
In a message dated 11/15/2017 12:48:24 P.M. US Mountain Standard Tim,  
cctalk at writes:

I have  been working on a HP 2640B terminal. It was mostly about fixing the
"screen  mold" problem and cleaning up the liquids that had been seeping out
from  the screen down into the bottom.

The small coaxial wire that connects  the 4.9152 MHz clock signal form the
power supply (never seen a crystal  controlled SMPSU before!) to the
backplane was broken off, but after fixing  that the terminal worked fine.
Just needed some adjustment to the  brightness.

With the correct terminfo installed it worked quite well as  a serial
terminal to a Linux box.

Then I tried the short 8008  programs that Christian Corti pointed  to


I  tried both a couple of times. The terminal enter the LOADER mode but  
hangs completely at the end. I tried different baudrates but no  difference.

The selftest STATUS line tell me 40<802 which should  indicate that there
are 4k memory in the terminal. However there should be  5k since there is
one 4k board and one combined control store and 1 k RAM  board. Maybe there
is a fault in the 1k SRAM? The terminal doesn't complain  though.

Regardless, the programs listed either starts at adress 30000  or 36000
which should then be within the available space.

The  question is, should these program work for the HP2640B as well? It has
a  8008 but my guess is that the firmware is different from the 2644. What
is  the joint experience regarding this? Has anyone ran these small  
above on a HP2640B?

The HP 2640B firmware consists of four  EA 4900 ROM chips which annoyingly
are not  anything like normal  EPROMs. So dumping will need special

Has anyone  dumped the HP 2640B firmware already? I didn't find it  on


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