HP 2671 Graphics ROM

[Tony Duell]

> > > The 2671 has an empty socket on the HP-IB interface board, the one 
> > > closest to the printer PCB is empty.

This sounds as though it might be a different cersion of the HPIB board, 
but I'll give the numbers in a second.

> Seems a good idea, I'll write down the part numbers so we can compare.

OK, I've dug my 2671G out and taken it apart. I find the instructions on 
the bottom very amusing. They tell you 'no user serviceable parts inside' 
and then tell you just how to take the cover odd. Go figure...

Anyway 

The PSU is a 02670-60070. I would be suprised if there are any changes there.

The HPIB interface is 02670-60072. U14 (2016 RAM) and U15 (ROM) are not 
fitted. U2 (an 8049 microcontroller) is 1820-2833. The DIP switches are 
set : 
1 Open (Mode)
2 Open )2K) -- this has no effect if U15 is not fitted!
3 Closed (Int ROM ) -- this means the 8049 will run from its internal ROM
4 Open  (Test)

The printer PCB (on the back of the thermaal print mechansim) seems to be 
iether a 02760-60067 or 02670-80084.

U3091 (8049) is 1820-3096
U101 (ROM) is 1818-1819

There is a 10 way dIP switch set as follows : 
1 Open
2 Open
3 Closed
4 Open
5 CLosed
6 Closed
7 Open
8 Closed
9 Open 
10 Closed

If I am reading the scheamtics properly : 

SW8 -> 8049 will run a program from it's internal ROM
SW10 -> power-fail or watchdog tinme-out will casue a rest
Others -> 8K esternal ROM (A12 is used), but note thatsince SW2 is open, 
PSEN/ does not enable the ROM. This means that the ROM is for data 
storage (font?) only, not for program code.

Unfortunately I don't ahve an 8049 programmer at the moment. It's 
something I must get roudn to buidling. Which means I can't dump the 
microcotnrollers...

-tony