Quatech DS-3000 User Manual

Quatech DS-3000 User Manual Manual pdf 19 page image

A D D R E S S I N GVI. A D D R E S S I N GEach channel of the DS-2000 uses 8 consecutive I/Oa d d r e s s l o c a t i o n s . T h e b a s e a d d r e s s e s a r e i n d e p e n d e n tbut must begin on an even 8-byte boundary (xxx0H - xxx7Hor xxx8H - xxxFH). The numbers xxx are controlled by theProgrammable Option Select (POS) and address decoders top r o v i d e c o m p l e t e 1 6 - b i t a d d r e s s i n g f o r e a c h c h a n n e l .S i x t e e n c h o i c e s o f b a s e a d d r e s s a r e p r o v i d e d f o r e a c hchannel and include the eight addresses defined as SERIAL1 through SERIAL 8. The remaining eight addresses are ac o n s t a n t 8 0 0 0 H o f f s e t f r o m t h e s e v a l u e s . A c o m p l e t etable of available addresses is given in figure 17. The1 6 5 5 0 u t i l i z e s i t s e i g h t a s s i g n e d a d d r e s s e s a s s h o w n i nfigure 2.VII. I N T E R R U P T SThe DS-2000 is capable of supporting four interruptl e v e l s , I R Q 3 , 4 , 7 a n d 9 . E a c h c h a n n e l m a y s e l e c t aseparate interrupt or one may be shared by both channels.If interrupt sharing is used, the interrupt pending (IP)b i t i n t h e i n t e r r u p t i d e n t i f i c a t i o n r e g i s t e r s h o u l d b eused to test for the source of the interrupt.C A U T I O N :T o m a i n t a i n c o m p a t i b i l i t y w i t h e a r l i e r p e r s o n a lcomputer systems, the user defined output, OUT 2, isused as an external interrupt enable and must be setactive for interrupts to be acknowledged. OUT 2 isaccessed through the 16550's MODEM control register.VIII. P R O G R A M M A B L E O P T I O N S E L E C TT h e I B M P S / 2 f a m i l y o f c o m p u t e r s u s i n g t h eM i c r o C h a n n e l b u s s t r u c t u r e u t i l i z e o n b o a r d r e g i s t e r sr e f e r r e d t o a s t h e P r o g r a m m a b l e O p t i o n S e l e c t ( P O S )r e g i s t e r s t o h o l d t h e a d a p t e r ' s c o n f i g u r a t i o ni n f o r m a t i o n . T h e f i r s t t w o P O S r e g i s t e r s h o l d a u n i q u eadapter identification number that has been issued to QuaTech for the DS-2000. This number is defined in hardwareand can not be changed. These registers are read only.iii