STATUS and CONTROL registers for IEEE-488 interfaces are given below. READIO and WRITEIO registers are presented for 9914 and 7210 based IEEE-488 interfaces.
IEEE-488 hardware is not supplied standard with most computers. For HTBasic, TransEra sells the GPIB-900 IEEE-488 Controller. The board fits in any XT or AT bus slot. The board incorporates the NI TMS9914 integrated circuit, the same controller used in HP BASIC workstations. This board provides compatibility with HP BASIC at all levels, including the READIO/WRITEIO level which accesses the 9914 registers directly.
HTBasic also supports most PC IEEE-488 boards from other manufacturers. These boards most often use the NEC PD7210 Chip and consequently are not completely compatible with HP BASIC. STATUS and CONTROL registers for the 9914 and the 7210 are the same, although some bits cannot be supported by the 7210. The READIO/WRITEIO registers of the 7210 are completely different from the 9914 used by HP BASIC. Different tables are given below for the 7210 and the 9914.
READIO/WRITEIO registers allow direct access to the interface hardware. You should not attempt to use these registers unless you are familiar with how the IEEE-488 chip is programmed.
The ON INTR 7 and ENABLE INTR 7 statements are supported. The values for the enable mask in the ENABLE INTR statement are the same as those for STATUS register 5, given below. Some interrupts are not supported by the 7210.
