Just some references: https://techheap.packetizer.com/computers/coco/unravelled_series/color-basic-unravelled.pdf This states DLOAD is input only On page 88, I don't see DLOAD listed - it goes from CLOADM straight to EXEC (so it is not clear to me on how DLOAD is implemented)
https://colorcomputerarchive.com/repo/Documents/Books/Unravelled%20Series/extended-basic-unravelled.pdf "DLOAD is the most obscure command in the Color Computer and absorbs a substantial amount of space in the ROM. DLOAD is so poorly understood because Tandy has never made the necessary companion routine, DSEND. DLOAD will DOWNLOAD a file over the RS 232 line from another system, however there is no companion routine, which will transmit a file over the RS 232 line to another Color Computer. Once a DSEND routine is built and made available to the masses, DLOAD will be much better understood." In the Extended BASIC ROM, it does have a section for DLOAD (and I think a DLOADM?). Maybe inspecting that code might give some idea on its origin. Maybe DLOAD was a way to stream in a newer test ROM or other system test/support software from a "larger" machine {e.g. a mainframe with a 6809E emulator?}). http://vtda.org/docs/computing/RadioShack-Tandy/8759038-780-SL_TRS-80ModelIIIBasicQuckRef.pdf I don't see DLOAD listed for the TRS-80 Model 3 (there is an INP keyword that talks about PORT 0-255, and this manual talks about supporting two cassette ports) https://ia801906.us.archive.org/30/items/Introduction_to_TRS-80_Level_II_BASIC_1980_Michael_Zabinski/Introduction_to_TRS-80_Level_II_BASIC_1980_Michael_Zabinski.pdf No DLOAD in the TRS-80 Level 2 BASIC (I spot checked to see if it might be under a different name, nothing stood out) https://archive.org/details/IBMBASICAV1.10Manual/page/n13/mode/2up No DLOAD in the IBM 5150 BASIC 1.10 (some suspects: LOG, LOF, GET/PUT, COMn statement, IN/OUT - maybe one this means DLOADM?). Appendix F-2 describes using BASIC to interface with the Async Serial IO Adapter, page F-8 describes using the INP keyword) Not sure if any that helps on the lineage of DLOAD. I looked at the Altair BASIC manual, didn't see any DLOAD there. And also the IBM 5110, (NOT a Microsoft BASIC) http://www.bitsavers.org/pdf/ibm/5110/SA21-9308-0_IBM_5110_BASIC_Reference_Manual_Jan1978.pdf Not sure if any of that helps, in terms of finding the DLOAD protocol. In the Color BASIC unravelled (first link), some of the code talked about using SPACE? As-in, something different than 8-N-1 (the SerialIO could also be used for a printer, so maybe 7-SPACE-1?). -SL On Mon, Jan 30, 2023 at 12:02 AM Jim Brain via cctalk <cctalk@classiccmp.org> wrote: > Over at the CoCo Mailing List, there's a archeological discussion about > the DLOAD BASIC command in older versions of the Color Computer BASIC. > It uses the serial port (and no doubt was designed for computer sharing > in classrooms or similar), but the questions are around how it was > designed and what inspiration is drew from. > > I infer MS wrote the code, and the protocol includes: > > P.ACK - Acknowledge - C8 hex. > P.ABRT - Abort - BC hex. > P.BLKR - Block request - 97 hex. > P.FILR - File request - 8A hex. > P.NAK - Negative Acknowledge - DE hex. > > Does that look like any protocol anyone has seen before? > > Jim > > >
