On Fri, 16 Jun 2017 22:56:18 +0100, David W Noon wrote: >I have seen only 2 hardware platforms that perform packed >decimal arithmetic: IBM and plug-compatible mainframes; Groupe Bull / >Honeywell-Bull / Honeywell/GE / General Electric mainframes derived from >the GE-600 series -- although these did not get packed decimal until >they became the Honeywell H-6000 series.
It's not strictly packed decimal arithmetic because there is no provision for a sign, but the 6502 did decimal arithmetic. The add and subtract instructions operate under control of the Decimal flag in the Status Register. When the bit is set, the operation acts upon two decimal digits in each byte. This was an improvement over the use of Decimal Adjust that was used on the 8080, 8085, z80, and 6800 processors to enable decimal arithmetic. -- Tom Marchant ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
