7 0
PCLS-848-P User's Manual
1) The clock rate of the computer. (4.77 MHz PC/XT to 16 MHz PC/AT to ?)
2) The software overhead.
3) The interface chip operating speed.
4) The clock rate of the DMAchip. (3 to 8 MHz)
5) DMA operating mode.
6) The operating speed of other processors that may be occupying the data bus. (e.g.
8087 or 80287 coprocessor)
7) The speed of handshake of the peripheral devices.
8) The IEEE-488 cable length and capacitance.
Factors 1, 4, and 6 are the nature of the PC. Factors 7 and 8 are determined by your
choice of devices and cables. For factor 5, you can choose block-transfer mode
DMAto get maximum speed with the risk that the PC may be hung. For factor 2, the
interface software routine is written with a lot of effort to maximize execution speed
by handling the overhead effectively. For factor 3, the NEC7210 was chosen because
it is an interface chip that can operate handshaking with 2 speeds. The user can choose
an appropriate speed according to the actual situation by setting bit 12 of <setting>
when calling ieinit( ) procedure. This setting will change the handshake timing T1, T6,
T7 and T9.
Bit 12 Speed
:
0
Slow
1
Fast
5.3. Interrupt
This IEEE-488 interface has the capability to interrupt the PC’s processor when
certain events happen. Microsoft Pascal offers some ways to handle interrupts. To
use these procedures to handle the SRQ interrupt from the IEEE-488 bus, you must
call the procedure ieinit( ) to set the IRQ channel. IRQ channel to Vector Number
Содержание PCLS-848-P
Страница 1: ...PCLS 848 P IEEE 488 INTERFACE CARD PASCA SUPPORT PACKAGE USER S MANUAL...
Страница 6: ...Figures Figuree 7 1 PCL 848A B Block Diagram 77...
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Страница 32: ...26 PCLS 848 P User s Manual If addr 0 or addr 30 ATN is set false String is entered...
Страница 37: ...CHAPTER 2 INSTALLATION 31 ieinit ioport myaddr setting...
Страница 42: ...36 PCLS 848 P User s Manual If addr 0 or addr 30 ATN is set false Long string is sent...
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Страница 83: ...CHAPTER 7 THEORY OF OPERATION 77 Figuree 7 1 PCL 848A B Block Diagram...
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Страница 95: ...CHAPTER 7 THEORY OF OPERATION 89...
Страница 97: ...CHAPTER 7 THEORY OF OPERATION 91 Handshake Timing Sequence...
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