scredit2 - terminal emulator and mainframe screen-scraper

Overview

scredit2 is a Windows reimplementation of SCREDIT, a special-purpose terminal program written at Michigan State University in the early 1980's. It will likely be of interest only to users of SCOPE/Hustler, the operating system that ran on MSU's Control Data Corporation mainframe. To run SCOPE/Hustler, you need the mainframe emulation programs DtCyber and FREND2.

Links

• scredit2's SourceForge project page
• FREND2's SourceForge website, which includes the DtCyber and FREND2 software.
• http://60bits.net, which has FREND and SCOPE/Hustler documentation.
• My SCOPE/Hustler website
• Tom Hunter's DtCyber site (somewhat out-of-date)

Status

Because this project is under active development and is not yet usable, I am not providing file releases yet. The current, very preliminary sources and Win32 executable are in scredit2.zip. Like all projects on SourceForge, scredit2 is free software. scredit2 uses the MIT X11 license, a license that places very few restrictions on your use of the software.

Background

The only likely audience for scredit2 will be users of frend2 and DtCyber, which emulate the CDC mainframe in question. With DtCyber, frend2, and scredit2, you can have the complete computing experience that MSU users had in the early 1980's. (DtCyber and frend2 are usable now without scredit2, but current telnet emulators do not provide the full experience enjoyed by those historical users.)

The original SCREDIT ran on 8080-based Ontel OEM terminals (no operating system!) and was soon ported to IBM PCs. Of course, SCREDIT used serial lines, not telnet as scredit2 will.  A 1988 executable PC version of SCREDIT is in screditcom.zip.  It runs only under MS-DOS.

The program had essentially four modes:

• A terminal mode with a large scrollback buffer. You could scroll back, edit, and retransmit lines previously entered in the session.
• A "full-screen" screen editor vaguely similar to, say, Windows Notepad. This was a front-end to an old-fashioned mainframe line editor which somewhat resembled the UNIX "ed" editor, or MS-DOS EDLIN. SCREDIT invisibly, in the background, sent editing commands to the mainframe to synchronize the mainframe file with what appeared on the screen.
• A VT220 emulator with no scrollback buffer.
• A file transfer mode. (Proprietary protocol, of course.)

I'm not sure I'll implement the VT220 mode, but I do plan on implementing the other modes.

The original SCREDIT was over 35,000 lines of interspersed 8080 and 8086 assembly language, so this reimplementation won't be done overnight.

/mrr riordanNOTTHISmr at earthlink dot net 2006-04-18