Host Data Link Layer: DDE Drivers

DDE Driver for Gigabyte Computer Services

A UNIX minicomputer platform supplied by Gigabyte Computer Services with applications written in COBOL.

Output Frame

A DDE frame from the Gigabyte Host to the PC may contain between 0 and 511 printable characters. On the wire, the frame must be prefixed by STX (02hex) and suffixed by ETX (03hex). Within the frame US (1Fhex) may be used to separate fields and _ (5Fhex) may substitute for SP (20hex) (should the Gigabyte Host's platform replace spaces by a cursor position command.

Input Frame

On the wire, a DDE frame to the Gigabyte Host from the PC is prefixed by a single byte and suffixed by CR LF (0D 0Ahex). A SP (20hex) is inserted as shown to ensure a minimum frame size of four bytes.

On the wire:Frame received:Usage:
SP data CR LFData: between 0 and 127 printable characters 
1 SP CR LFControl: FSNo (cancel)
2 SP CR LFControl: GSYes (proceed)
3 SP CR LFControl: RS 
4 SP CR LFControl: USRepeat previous frame
0 SP CR LFControl: ESCTerminate DDE immediately

DDE Driver for Sutton Computing

A UNIX minicomputer platform supplied by Sutton Computing with applications written in COBOL.

Output Frame

A DDE frame from the Sutton platform to the PC may contain between 0 and 511 printable characters. On the wire, the frame must be prefixed by STX (02hex) and suffixed by ETX CR LF (03 0D 0Ahex). Within the frame CR LF (0D 0Ahex) or BEL (07hex) may be used to separate fields.

Input Frame

A DDE frame to the Sutton platform from the PC comprises all characters on the wire up to CR (0Dhex). The Sutton platform must echo every character sent (including control codes). If no echo is received after six seconds the PC will repeat the character. The driver will tolerate any multiple echoes ensuing from CR.

On the wire:Frame received:Usage:
data CRData: between 0 and 127 printable characters 
FS CRControl: FSNo (cancel)
GS CRControl: GSYes (proceed)
RS CRControl: RS 
US CRControl: USRepeat previous frame
ESC CRControl: ESCTerminate DDE immediately

Keyboard Mapping

The PC approximately emulates the Lear Siegler ADM3A/5 and Wyse 120 terminals. The keyboard mapping is:

PC KeyboardUsageOpus 4 KeyboardOn the wire
CTRL+AAddF11SOH J CR
CTRL+CChangeF12SOH K CR
CTRL+DDeleteF13SOH L CR
CTRL+EEnquireF14SOH M CR
CTRL+QQuickF16SOH O CR
HOMEClear FieldClear FieldESC A
SHIFT+HOME  ESC {
ENDClear to EOFKEYPAD .ESC T
SHIFT+END  ESC Y
PGUPSkip to previous pagePrev ScrnESC J
PGDNSkip to next pageNext ScrnESC K
INSERT  ESC q
SHIFT+INSERT  ESC r
DELETEDelete Character ESC W
SHIFT+DELETEDelete Line ESC R
SHIFT+F3 F13SOH L CR
SHIFT+F4 F14SOH M CR
SHIFT+F5 F15SOH N CR
SHIFT+F6  F16SOH O CR
ESCEscapeESCESC ESC

DDE Driver for the XKO Group

Various minicomputer platforms running UNIX or Windows NT supplied by the XKO Group with applications written in COBOL. GO.EXE provides two versions of the XKO Group driver, as selected by the DDE field in the Change Settings dialog:

Set DDE field to:When Host platform is:
0UNIX
1Windows NT

The only difference is in the echoing of characters in Input Frames.

Output Frame

A DDE frame from the XKO Host to the PC may contain between 0 and 511 printable characters. On the wire, the frame must be prefixed by STX (02hex) and suffixed by ETX (03hex). Within the frame US (1Fhex) may be used to separate fields and _ (5Fhex) may substitute for SP (20hex) (should the XKO Host's platform replace spaces by a cursor position command).

Input Frame

On the wire, a DDE frame to the XKO Host from the PC is prefixed by a single byte (identifying the frame type) and suffixed by CR (0Dhex).

The XKO UNIX platform must echo every character sent to it (including control codes). If no echo is received after six seconds the PC will repeat the character. The driver will tolerate multiple echoes ensuing from CR.

The XKO Windows NT platform, however, does not echo any character sent to it.

On the wire:Frame type received:Usage:
SP data CRData: between 0 and 127 printable characters 
1 CRControl: FSNo (cancel)
2 CRControl: GSYes (proceed)
3 CRControl: RS 
4 CRControl: USRepeat previous frame
0 CRControl: ESCTerminate DDE immediately

The PC enters DDE mode upon receipt of STX (02hex) and reverts to Terminal Mode after sending 0 CR (30 0Dhex) to the Host.

Keyboard Mapping

When the PC keyboard is enabled (by the /K switch on the MS-DOS command line), the PC approximately emulates a Wyse WY-120 terminal.

WY-120 keys used by XKO Group (Narborough) applications but not available on the PC keyboard are mapped as follows:

WY120 KeyboardPC KeyboardUsageOn the wire
 HOME ESC A
CLR LINEEND ESC T
PAGE PREVPGUP ESC J
PAGE NEXTPGDN ESC K
F14SHIFT+F10 SOH M CR
F15SHIFT+F11 SOH N CR
F16SHIFT+F9 SOH O CR
F16SHIFT+F12 SOH O CR

When the PC keyboard is disabled, pressing Ctrl+F1 during DDE mode requests DDE shutdown. Pressing Ctrl+F1 in Terminal Mode sends the ESC control frame (0 CR) to the XKO Host.

The Protocol Handbook