Playing with HP2640B

[Mattis Lind]

2017-11-16 1:25 GMT+01:00 <COURYHOUSE at aol.com>:

> is there a  dif  between  40 a  and  40 b   with the firmware/loader/etc?
> Ed#
>

I assume there are a difference. The document linked to below at least tell
that the original A had a completely different set of ROM chips whilst rev
date "April 76" only had the first ROM different. The three others were the
same.

http://bitsavers.trailing-edge.com/pdf/hp/terminal/HP_262x_264x_roms.pdf


>
> In a message dated 11/15/2017 12:48:24 P.M. US Mountain Standard Tim,
> cctalk at classiccmp.org 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
>
> http://computermuseum.informatik.uni-stuttgart.de/dev_en/hp2644/diag.html
>
> and
>
> ftp://computermuseum.informatik.uni-stuttgart.de/hp/hp2644
>
> I tried both a couple of times. The terminal enter the LOADER mode but just
> 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 programs
> 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
> considerations.
>
> Has anyone dumped the HP 2640B firmware already? I didn't find it on
> bitsavers.
>
> /Mattis
>
>