Any own an 11/725...?

[Tony Duell]

> 
> Actually, with access to the micro instructions you can often  
> substantially improve the run-time of a given program. The Modcomp II  

I am something of a PERQ-fanatic, so I am well aware of this. The classic 
PERQs have user-modifyable microcode, and the hardware is not designed 
for a particular isntruction set (there is no hard-wired instruction 
decoding at all, unlike, say, a PDP11/45), so you can pretty much do what 
you like. 

Under POS (PERQ OS or Pascal OS, depending on which book you read), you 
were not expected to write any machine or assembly langage (Q-codes). The 
assember was not included in the OS distribution, and the manual doesn't 
really epxlain the Q-codes. But the microcode assember and placer were 
included, the manual does describe user-written microcode. 

For some things, like directly accessing I/O ports (say for custom 
hardware -- like the tape streamer interface hack) you _have_ to use 
microcode on the PERQ. But you can also use it to speed up critical 
routines in your program (just don't try and improve the raster operation 
microcode, you won't do it. Period.)

-tony