wei@princeton.UUCP (P Wei) (01/15/86)
Can anybody tell (email) me what the CPU is in HP-87 computer ? 8088 or other 8-bit microprocessors ? Thanks. HP Wei (wei@princeton)
tim@hpfcla.UUCP (01/22/86)
The HP 85, 86 and 87 all use an HP proprietary processor. Having worked on the 80 series I/O, I found it a nice processor. It was designed for the 80 series desktop and a handheld product (a derivative of which is the HP 75). Because of this background, low power and few pins were a prime factor. The processor is an 8 bit in a 24 pin (?) package done originally in CMOS (but as I remember, the production version was NMOS). It multiplexed data and address over 8 I/O lines. There was a address high and low strobe. Sequential addresses did not require a new pair of address bytes, just a read or write data strobe (the peripheral chips took care of incrementing their address). The processor has 64 8-bit registers. The first 32 of these are addressable as 1 or 2 byte entities (byte or word). The second 32 of these are addressable as 1, 2, 3, 4, 5, 6, 7 or 8 byte entities. The way this works is through ARP (address register pointer) and DRP (data register pointer) specifications (sort of a source/destination) and through a single byte/ multibyte indication on the instruction. In the following, the register numbers are in octal. I am a little fuzzy on the 'syntax'. Some 'typical' sorts of assembly code looked like: LDB R1,R2 single byte load from R2 into R1 LDM R0,R2 2 byte load from R2/R3 into R0/R1 BIN go into binary arithmetic mode ADB R40,R50 add 1 byte R40 to R50 and put result in R50 ADM R40,R50 add 8 bytes R40-47 to R50-57, result in R50-57 (this is a 64 bit add) ADM R44,R54 add 4 bytes BCD go into decimal mode ADM R40,R50 16 BCD digits R40-47,R50-57 result in R50-57 So the amount to be operated on depends on where you start. Outside of these features, the CPU had normal sorts of operations. The 85 accessed 32K of RAM, 32K of ROM and some memory mapped I/O. The top 8K of ROM was block switched for option ROMS. The 86 and 87 had block switched RAM and supported up to 512K (I think). There is an assembler available for the 80 series. There is also a Z80 CPM card available (I think only for the 86/87). As I remember, there was an HP Journal article on the processor (for the 85) in the July 1979 issue. Tim Mikkelsen hplabs!hpfcla!tim