Got a HP 2648. Now what?

[Tony Duell]

> 
> Oh I can definitely think of a reason. The HP 2225C HP-IB Thinkjet printer. 
> Many terminals had printer hookups....

Unless I'm mis-remmebring something, the 2225C has a cnetronics parallel 
interface. You meen the 2225A (HPIB). The 2225B is HPIL (and battery 
powered), the 2225D is RS232.  I've had all of them across my bench at 
one time or another.

The 2225A is odd. The CPU in the thinkjets has a built-in HPIL port 
(which is used in the normal way in a 2225B). The HPIB version has a 
lttle non-isolated HPIB-HPIL converter that llinks to said HPIL port. The 
version built into the Integral is really an HPIL version, with a 1LB3 
HPIL chip to link it to the 68000 bus (again, with no isolating pulse 
transformers.

The RS232 and Centronics models ignore the HPIL interface on the CPU 
chip, and have interface circuits connected to the processor data lines. 
The CPU firmware is therefore different.

-tony