Path: csiph.com!aioe.org!.POSTED!not-for-mail From: =?UTF-8?Q?Arne_Vajh=c3=b8j?= Newsgroups: comp.lang.java.programmer Subject: Re: Can Java compute 9^(9^9) ? Date: Sun, 10 Jun 2018 21:17:06 -0400 Organization: Aioe.org NNTP Server Lines: 79 Message-ID: References: <578c1151-0e93-4316-8b82-32652421e022@googlegroups.com> NNTP-Posting-Host: PBuS014lhzVyHjLbXmo/ZQ.user.gioia.aioe.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit X-Complaints-To: abuse@aioe.org User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.8.0 Content-Language: en-US X-Notice: Filtered by postfilter v. 0.8.3 Xref: csiph.com comp.lang.java.programmer:38359 On 6/10/2018 6:48 PM, bursejan@gmail.com wrote: > Am Montag, 11. Juni 2018 00:29:14 UTC+2 schrieb Arne Vajhøj: >> On 6/10/2018 5:31 AM, bursejan@gmail.com wrote: >>> Am Sonntag, 10. Juni 2018 11:13:19 UTC+2 schrieb Martin Gregorie: >>>> On Sat, 09 Jun 2018 23:29:53 +0000, Volker Borchert wrote: >>>>> j4n bur53 wrote: >>>>>> Interestingly IBM, also for their new POWER9, >>>>>> still provides BCD coding support. >>>>> >>>>> Is it part of ANSI COBOL? >>> Packed BCD is supported in the COBOL programming >>> language as the "COMPUTATIONAL-3" (an IBM >>> extension adopted by many other compiler >>> vendors) or "PACKED-DECIMAL" (part of the >>> 1985 COBOL standard) data type. It is >>> supported in PL/I as "FIXED DECIMAL". Besides >>> the IBM System/360 and later compatible >>> mainframes, packed BCD is implemented >>> in the native instruction set of the >>> original VAX processors from Digital >>> Equipment Corporation and some models >>> of the SDS Sigma series mainframes, and >>> is the native format for the Burroughs >>> Corporation Medium Systems line of >>> mainframes (descended from the 1950s >>> Electrodata 200 series). >> >> Note that there is a difference between supporting >> BCD format in memory and having the CPU support it. >> >> Systems supporting BCD format in memory can process >> them in 3 different ways: >> 1) BCD instructions in the ISA implemented in actual >> silicium >> 2) BCD instructions in the ISA implemented in >> micro-code >> 3) non-BCD instructions >> >> All will support COBOL COMP-3 fine. >> >> #1 will be fastest, so if COBOL COMP-3 is a huge >> part of the actual workload for a given computer >> architecture then it makes sense. > > For VAX it was possibly option 2), at least > wikipedia says: > > Architectures with instruction sets > implemented by complex microprograms > included the IBM System/360 and Digital > Equipment Corporation VAX. > https://en.wikipedia.org/wiki/Microcode > > And the instructions were so called decimal > string instructions, I guess: > > Decimal = Decimal instruction group > > ADDP4 ADDP6 ASHP CMPP3 CMPP4 > CVTLP CVTPL CVTPS CVTPT CVTSP > CVTTP DIVP MOVP MULP SUBP4 > SUBP6 > > Because there is always a length parameter, > I guess option 1) does not really exist. At > least if the aim is decimal strings. Yes - VAX xxxP is BCD. Length is necessary as there is a need to support different lengths. I would think even a pure silicium solution would need that. Arne