• Stopped Working?

    agp.cooper • 08/01/2021 at 11:38 • 0 comments

    Stopped Working?

    Fired up the programmer to program the system disk for  MyCP/M V3, and it freezes:

    Upload HEX8-16 to W29C020 Flash ROM (no SDP)

Ready for upload
S:0
A:0
A:80
A:100
A:180
A:200
A:280
A:300
A:380
A:400
A:480
A:500
A:580
A:600

    Swapped the USB cable, the flash chip and cleaned the board to remove flux. Checked the HEX file and the GTK Terminal settings. No  solution. Tried the older version of the code, same.

    Actually there is no flow control, no data being sent (according tothe Nano LEDs), no movement on the data sent bar, so it has to be GTK Term is waiting for something or is stopped.

    I have just completed a fresh Linux Mint Mate 20.2 install so it must be GTK Term or the USB port. I guessing its GTK Term.

    Installed picocom and it uploaded the system hex file without problem but My CP/M V3 did not boot up. This is the part I hate. Trying to work out where the fault lies.

    AlanX

  • Success

    agp.cooper • 06/29/2021 at 02:19 • 0 comments

    Success

    Reworked the code for the new board. Added a patch for the schematic error.

    Here it is working:

    And here are the boards:

    Debugged

    Had some problem with the Flash ROM chips from my MyCP/M V2. The chips (both W29C020Bs) had corrupted pages 0x001680, 0x001700, 0x001780, 0x001800, 0x001880, 0x001900 and 0x001A00. They even had exactly the same bad memory locations and values. It took me long time to believe the problem was the chips rather than my firmware. In the end I tried a new chip and it programmed fine. I suspect that when My CP/M crashed it was endlessly writing to these locations on both chips causing failure. The bad segments were in my CBIOS. So no wonder I could not understand what was happening.

    Here is a happy MyCPM V2 and the Flash ROM Programmer:

    AlanX

  • Reworking the existing Flash ROM Programmer

    agp.cooper • 06/27/2021 at 13:17 • 0 comments

    Reworking the existing Flash ROM programmer

    A new PCB is coming that allows programming of larger capacity Flash ROM chips than the AT29C256. But it makes an excellent test bed for the firmware.

    Here are the first and second generation Flash ROM programmers:

    These programmers can only address 32x8kb in software. With two address latches (i.e. 74HC374) the address space expands to 512x8kb (or more).

    HEX8-16 Support

    The firmware interprets HEX8, line types 0 (data) and 1 (end of file), and the Hex16 line type 2 (extended segment address). Hex16 line type 3 (start segment address) is not supported. Using line type 2 allows access to 1M of address space.

    Multiple hex files can be include in the upload file and files can be shifted (if appropriate) using line type 2.

    Options

    At the moment the firmware only support the AT29C256 but the plan is to support on the fly parameters for ROM size, Page size, Software Date Protection and Boot Lockouts.

    Upload speed

    Really there is no reason to upload data faster/slower than 9600 baud. No handshaking is required.

    Schematic

    Here is the new schematic. The current firmware is not compatible due to design changes:

    Looking at the schematic now, I see a small error. A18 attaches to D7 rather than D4. No matter I can fix it if there is a new generation.

    AlanX