Re: System 3 Code

Most System/3 computers had disk drives.  Only the very early System/3 Model 
10s 
lacked disk I/O.

The first two models were System/3 Model 10 (first a card-only version with a 
MFCU 
(multi-function card unit); later one with disk I/O and MFCU)) and System/3 
Model 6 
(no punched cards, keyboard/printer console, disk).  System/3 was announced in 
1969.

Later models were quite powerful for their day.  My last project as an IBM 
Systems
Engineer was designing and programming an online (3270 CRT terminals) system 
for a 
credit union on a System/3 Model 15D.  The system went live on January 3, 1978.

That particular System/3 had 384K bytes of memory, 3 partitions, and 
about 140 MB of disk storage (two removable 3340 disk drives - the platters, 
heads, 
and arms were sealed inside the removable cartridge).  By October 1976, the 
credit union 
was running 25 3270 terminals on the System/3.  By that time, most System/3s 
were cardless 
with unit record I/O handled by direct-attached 3741 diskette data stations.

The programming language was RPG II, which supported sequential, and direct 
(by RRN or KEY), disk I/O.  Exception output was also supported.  There were 
no externally described files, no IF, DO, SELECT, FOR, CASxx, etc., op codes.  
There was no database (flat files only), no journaling, and no commitment 
control.

RPG II was the only language at first; it was later joined by COBOL and FORTRAN.

Relational databases hadn't been invented.  Spooling was supported only for 
system printers (I don't remember whether more than one per system was 
supported)
and the system spool file could fill up!  Maximum program size was 64K.

The Communications Control Program (CCP) supported online programming.  
CCP programs could not exceed 32K.  The RPG II compiler supported external 
buffers 
and external memory resident overlays.  Screen I/O was supported by DFF 
(Display File Facility), which I think was part of CCP.  There was no SEU, 
but a field developed program for online editing of source members was 
widely used.  The disk was organized in two major parts: a library section 
(contained 
procedures (OCL - operation control language), source, object (executable 
programs) 
and relocatable object (generally system-provided to be be link edited into 
programs); 
and, a file section for user data, including a VTOC (volume table of contents).

System/3 was the ancestor of System/32, System/34, System/38, System/36, 
and AS/400, in that order.  System/32, System/34 and System/36 all were 
System/3 derivatives.  System/38 and AS/400, of course, were and are 
completely different and far more advanced than the others.

That's the way it was (as best I can remember) and is (as I best can 
understand).  Any errors are certainly my own!

I would have to agree that "System/3 code" is very old indeed!  It certainly 
wasn't as bad as walking 5 miles to and from school in the snow, uphill both 
ways, 
or programming on card-only machines, but compared to today's programming 
environment, it was pretty primitive.

Programmers whose experience only goes back as far as AS/400 (announced 1988) 
or even System/38 (announced 1978, shipped 1980), often don't know how good 
things are.


Mel Rothman


booth@MartinVT.com wrote:
> 
> System 3 machines were mostly card machines.  They used 96  column punched
> cards to store data.  RPG responded to those needs, not to magnetic media.
>  You designed with record formats, matching records, level breaks, and
> left-side indicators.  there were no parms, no calls, no *INZSR, no
> externally described files, and no logical files.  you sorted the records
> to establish order for reports.   Source code was numbered in the first 5
> columns so you could put your card stack back in order when you dropped
> it.
> 
> 
> _______________________
> Booth Martin
> Booth@MartinVT.com
> http://www.MartinVT.com
> _______________________
> 
> Lisa.Abney@universalflavors.com
> Sent by: owner-rpg400-l@midrange.com
> 09/26/2000 08:42 PM
> Please respond to RPG400-L
> 
> 
>         To:     RPG400-L@midrange.com
>         cc:
>         Subject:        System 3 Code
> 
> Just a curiousity question ...
> 
> A contractor recently described some very old code as "System 3" code. Any
> idea
> what this is?  RPG II is as far back as I go!  I do know it's running on
> an
> AS400 in 36 mode.
> 
> +---
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