23 Sep
2004
23 Sep
'04
3:56 a.m.
>>>> "Doc" == Doc Shipley
<doc(a)mdrconsult.com> writes:
Doc> Ed Kelleher wrote:
> DEC PDP11/23 CPU has sockets for 2 extra chips (40
pin DIPS).
>
> One is hardware floating point. This is fairly common.
>
> The other for a CIS - Commercial Instruction Set with full set of
> decimal instructions as you list.
Doc> The dual-height 11/03 processor allows a CIS as well. I have a
Doc> couple that have that chip. As far as I can determine, both
Doc> those machines were used to sort, analyse, and archive incoming
Doc> raw data.
Doc> Honestly, though, I don't think I've ever run a job on the /03
Doc> that touched the CIS.
I would assume that Cobol and (possibly) RPG would have an option to
use CIS if available, but no other language is likely to do so.
There was a DEC internal prototype of an 11/70 with CIS added; it was
called 11/74 I believe (not to be confused with the SMP machine also
referred to as 11/74 that the RSX development team used). Apparently
it was canceled shortly before it was ready to ship. Nasty rumors
claimed that this was because it was outperforming the 11/780 in every
way; I don't know how valid that might be.
paul